Determining break/border of movement

Determining break/border of movement

We are searching data for your request:

Forums and discussions:
Manuals and reference books:
Data from registers:
Wait the end of the search in all databases.
Upon completion, a link will appear to access the found materials.

A population given inhabiting an area. I can trace every individual and I've got the hypothesis there is a break in distribution like individuals born in the upper half of the area will rarely move to the lower half and vice versa.

Tracking each individual how can I determine the line/border which divides the population in a upper and lower half. What's the math or algorithm behind to draw this imaginary line?

There are a lot of approaches to this kind of problem. Starting with the simplest approach I think you'd benefit from using a K-means classification, with K=2 (or higher numbers to address @Luigi's concerns about model bias.) Once you've defined the geometric center of each population, you can treat them as foci, and use the equidistant points between each focus to define the boundary of interest. That does import another assumption (that the boundary is equidistant to the two points).

A more sophisticated way to divide two clusters is with a support vector machine but because this is a machine learning approach, you'd need to manually annotate a number of training data sets as "group 1" or "group 2." But after training, the SVM will define the optimal boundary (hypersurface) between these groups.

The two types of approaches (clustering versus machine learning) differ in where the manually-imported assumptions lie. One can combine them fruitfully -- using K-means to define the populations and SVM to define the dividing boundary.

Top 4 Types of Chromosomal Aberrations

Chromosomes contain a number of genes on them. The genes are arranged in linear fashion. The number and also the positions of genes on a chromosome are fixed. When a chromosome is broken into several pieces, the healing (reunion) of the segments takes place and it is possible that the two ends of the fragments unite together leaving one or more acentric parts free (Fig. 22.3).

The acentric pieces of chromosomes as mentioned earlier disappear. The healed segments will form a chromosome that will be deficient for some of the genes, particularly those found on the lost part. Depending upon the length of chromosome segment lost in this way, the loss involves one gene or a block of genes.

The loss of a section of genetic material and genetic information from a chromosome or linkage structure is termed deficiency or deletion. Deletions may be produced in several ways, such as by loss of terminal acentric fragments or interstitial segment of chromosomes Fig. 22.3).

Although in practice deletions frequently refer to losses of terminal as well as intercalary segments of chromosome, at molecular level the deletions, of course, can be so small that many mutant loci are in reality deficient for one or more nucleotides in the DNA molecule. If the deficiency is large, the chances are there that the cell may die.

However, if the deficiency is small, the cells may persist. Should such a cell be fertilized egg, the net effect will be production of a dominant lethal. Homozygous deletions are usually lethal but heterozygous deletions appear as normal mutations.

Deficiency can be detected by its two characteristics, namely, genetic effects and cytological effects.

Genetic Effects of Deficiency:

These are primarily due to the loss of genetic information and secondarily due to qualitative changes in the genotype as well as the change of genie balance. Deficiencies have been useful in determining the exact locations of genes on the chromosomes.

One of the genetic effects of deficiency is pseudo-dominance. Pseudodominance occurs when the chromosome that carries the deletion of dominant allele pairs with a normal homologous chromosome carrying the recessive allele.

In absence of dominant alleles the recessive alleles would be expressed in phenotype as if they were dominant. This is called pseudo-dominance. If some of the corresponding genes have tendency of lethal effect in double dose, they will be lethal in single dose (recessive lethality). The chromosomes with deletion never return to a normal state.

Cytological Effects:

The existence of relatively large deletions in the chromosome complements of eukaryotes may be proved cytologically

(i) By the occurrence of centric and acentric chromosome fragments in mitosis, and

(ii) By the absence of regional pairing during first meiotic prophase. If the cell is heterozygous for deletion, i.e. it has a normal chromosome and a deficient homologue, then during synapsis, the chromosomes pair precisely gene by gene all along the homologous region and in deficient region, however, the normal chromosome will not pair.

Therefore, a buckling (loop) will develop in the normal homologue at the point of intercalary deficiency (Fig. 22.4). It is, therefore, known as buckling effect. Such a configuration is called deficiency loop or compensation loop and can be observed under microscope.

The pseudominance and the buckling in synapased chromosomes can thus be used to determine the exact location of genes in the deficient region. The genes which are known to be missing in the deficiency must be located in the buckle or loop region of homologue.

An example of deficiency is known in X-chromosomes of Drosophila in which few bands are missing from the tip of X-chromosome. Such a deficiency characterised by heteromorphic bivalent during prophase of first meiosis and has well marked phenotypic effect in Drosophila.

Notches in the wing margins of female fly are actually due to this sort of deletion in X-chromosomes. It is lethal in males. Many of the minute (bristles) series of mutants in this fruit fly are also due to deficiency.

In the lower organisms, for example, Chlamydomonas, yeasts and some fungi, deficiencies are totally lethal, i.e., they result in the death of the individuals.

Chromosomal Aberration: Type # 2. Duplications:

A structural change resulting in the doubling of genes in a section of the chromosome of prokaryotes and eukaryotes is referred to as duplication. In other words, the inclusion of extra part or duplicated gene sequence of a chromosome beyond the normal complement is called duplication.

If a segment of one chromosome is incorporated in another homologous chromosome, it is called intrachromosomal duplication (Fig. 22.5), but if the duplicated chromosome segment is either incorporated into a non-homologous chromosome or occurs as a fragment in the chromosomal set it is called interchromosomal duplication (Fig. 22.5).

The duplicated segments contained within a single chromosome could exist in one of the following configurations depending upon the position and sequence of the duplicated genes.

(i) Direct tandem duplication in which the duplicated gene sequence lies just next to normal corresponding section and the sequence of genes with respect to centromere is the same in duplicated segment as in the normal section of the chromosome.

It will be clear from the following gene sequences in the normal and duplicated chromosomes:

(ii) Reverse tandem duplication in which the duplicated section with reverse gene sequence lies adjacent to normal sequence as shown below:

(iii) Displaced direct duplication in which the duplicated section is not adjacent or contiguous with the normal section (i.e., separated by other segment).

The duplicated and normal gene sequences may be in the same arm (intra arm) or in two different arms of the chromosome (inter arm duplication):

(iv) Displaced Reverse duplication in which the duplicated section with reverse gene sequence is separated from normal segment by other segment as shown in the following chromosomes:

(v) Transposed duplication in which the duplicated gene sequence is attached to another position owing to inter-chromosomal duplication.

The size of duplicated segment may vary considerably. The smallest duplications that can be investigated cytologically are those of single band of polytene chromosomes. However, the whole arm of the chromosomes may be duplicated, thus giving rise to isochromosome. Where all linkage groups or chromosomes in the haploid chromosome set are doubled, this is referred to as genome mutation.

Duplication may arise in several ways. One of the most common methods is unequal crossing over, a process which produces one chromosome with duplication and another with deficiency. This is primary structural change of chromosome.

The schematic representation of gene duplication in chromosome by unequal crossing over is shown in Fig. 22.6.

Duplications may also occur due to crossing over in inverted or translocated segments. (Secondary structural mutation of chromosome)

Duplications in general, are much more viable than deficiency. A heterozygous duplication has an appearance similar to deletion. Duplications sometimes appear as dominant mutations. By duplication an allele may be duplicated, triplicated or multiplicated, hence duplications may be utilized a studying the effect of various quantitative doses of members of an allelic set.

Well known example of duplication which had a significant impact on genie theory is Bar-eye mutation in Drosophila. With the discovery of chromosomal nature of this case, it was found that extra pieces of chromosome were associated with a normal X-chromosome duplicating and triplication section of it (Fig. 22.7).

The Bar-eye, a sex-linked incompletely dominant mutation responsible for the development of rod-shaped eye with reduced eye facets, appeared spontaneously in a wild type stock of Drosophila melanogaster with round eyes. Homozygous stock of Bar-eyed mutants produced flies with normal eye and flies with even more reduced eye (Double Bar) in approximately equal frequency.

These observations suggested that Bar locus was very unstable but the appearance of wild type and double bar flies in equal numbers could not easily be explained. Moreover, the two mutant phenotypes appeared in the progeny when Bar-females were crossed with normal males, and not in the progeny of Bar-males crossed with normal females.

Drosophila is unusual in the sense that meiotic crossing over occurs only in females and not in the males. This observation suggests that mutation was not responsible for the wild type and double Bar progeny and that Bar might somehow be related to meiotic crossing over.

In 1925, Sturtevant using females homozygous for Bar (B) but heterozygous for forked bristles gene f) and for fused wing veins (gene fu) demonstrated that the normal and double Bar flies were products of crossing over within the Bar locus. Sturtevant found that some normal and some double Bar flies were recombinants, each with one or the other flanking marker (‘f’ or ‘fu’).

Sturtevant hypothesis of unequal crossing over was supported by Bridges in 1936. Bridges studied the chromosomes of wild type Bar eyed and Double Bar eyed flies and noticed the presence of single 16A segment in normal eyed, two 16A segments in tandem in Bar eyed and three continuous 16A segments in double Bar eyed (Fig. 22.7). By unequal crossing over in homozygous Bar females one 16Å.

Segment is transferred to a chromatid with duplication and consequently a chromosome with only a single 16Å segment (normal type) and another with three 16Å segments (Double Bar) are recovered. Duplication and reduplications of Bar region can be easily seen in the salivary gland chromosomes (Fig. 22.7).

The chromosomes of Drosophila salivary gland are large and easily distinguishable. They replicate several times but do not divide. So, each chromosome appears like a ‘rope’ of about 1,000 tightly coiled chromatids—a polytene chromosome. The genes for Bar eye and several other characters have been, in fact, cytologically pinpointed to specific bands or chromomeres.

In com and peas, a number of duplicating factors are known. Duplications like deletions may be so small as to be molecular. Since they change the genie balance, they may produce abnormalities m body characters. Duplications are considered to play a role in origin of new genes through functional diversification of duplicated members.

Like deficiencies, duplications have diagnostic cytological and genetically effects.

Cytological Effects:

The existence of relatively small duplications in the chromosome complements of eukaryotes may be proved by the appearance of regional distortions of duplicated chromosome during pairing in first meiotic prophase or somatic pairing in specialized tissue like salivary glands of Diptera.

Crossing over in reverse tandem duplication may result into a dicentric chromosome. This can be frequently observed in maize. As the two centromeres move to opposite poles, a chromosome bridge is formed which later on breaks at any point along the bridge.

The broken ends are sticky and the replication of the broken pieces may result in two sister chromatids which may be joined together due to their sticky ends. Thus, whole chromosome arm may be duplicated giving rise to isochromosomes. In sporophytic tissues of plants, the isochromosomes are uncommon.

Genetic Effects:

The genetic effects of duplications depend on the genetic information the duplicated segments contain and the change in genie balance effected by them. In homo and heterozygous state they may cause an increase or decrease in the viability of their carriers and in extreme cases may act as lethals.

Since the duplications supply the additional genetic material and change the genie balance, they play important role in evolution at individual and population levels.

Under evolutionary conditions, small duplications may provide a basis for the mutational differentiation of genetic material and the different copies of the same gene may change in different directions without disturbing the normal functions of an organism.

The cases in which different gene pairs affect the same character (as for example, multiple factors, complementary factors) possibly arose initially after duplication of single genes. The repetition of DNA sequences frequently seen in highly evolved organisms is a direct indication to this.

Chromosomal Aberration: Type # 3. Translocation:

Chromosomes may break into two or more fragments, each with a raw end. These segments may reunite and during reunion either the pieces of the same chromosome or the pieces of the non-­homologous chromosomes may be fused. Ionising radiations such as X-rays and gamma-rays are frequently used to break chromosomes for producing structural changes.

In this process, a part of the chromosome is transferred to another non-homologous chromosome within the chromosome complement.

In other words, a translocation is a chromosomal rearrangement which involves:

(i) The unidirectional transfer of a chromosome segment and its gene sequence to a different chromosome within the chromosome complement, and

(ii) The exchange of segments between non-homologous chromosomes. In this way, translocation only results into a change in the sequence and position of genes, their quantity being unaffected.

Types of Translocation:

1. Simple Non-Reciprocal Translocations or Transpositions:

In this process, a piece of one chromosome is transferred to a non-homologous chromosome.

It can be of two types:

(i)Simple translocation or Terminal transposition,

(ii) Shift translocation or Interstitial transposition.

(i) Simple Translocation:

When a chromosome breaks into two parts due to external or internal stress, one of the two segments of the broken chromosome may become attached to the natural end of the nearest chromosome which may not be its homologue. This is simple translocation.

Suppose, there are two non-homologous chromosomes A B C D E F G and TUVWXYZ. If F G part of the first chromosome is transferred to second chromosome, a new chromosome TUVWXYZFG would result as shown in Fig. 22.8. In this non-standard or translocation chromosome, F G is said to be in simple translocation state.

In the normal course, the terminal transpositions are not common because the raw ends or the telomeres of unbroken chromosomes are not sticky.

(ii) Intrachromosomal, Shift Translocation or Interstitial Transposition:

In this, an interior or interstitial segment of a chromosome that is induced by two breaks is incorporated interstitially into another non-homologous broken chromosome, the latter being induced by a single break. It is also called intercalation or insertion.

If the sequence of genes in the translocated segment is the same as that in the original segment with respect to centromere, it is referred to as encentric translocation. But if the sequence of gene loci in translocated chromosome segment is reversed it is called dyscentric translocation.

2. Reciprocal Translocation:

When a break occurs at a point where two non-homologous chromosomes touch each other, the broken end of one chromosome may become united with the broken end of second chromosome and that of second chromosome becomes attached to that of first, this is reciprocal translocation.

Suppose, there are two chromosomes A B C D E F and G H I J K L. These two after reciprocal translocation may produce chromosomes A B C J K L and G H I D E F as shown in Fig. 22.9. The reciprocal translocation is the most common type of translocation.

If there occurs two breaks in each of the two non-homologous chromosomes, the reciprocal translocation of intercalary segments may be obtained, but it is very rare.

The reciprocal translocation is like crossing over except that it involves exchange between the segments of two non-homologous chromosomes. It is sometimes called “illegitimate crossing over”.

The origin of translocations is interpreted either according to the breakage-reunion or the exchange model. The unit of translocation may be the chromosome (chromosome translocation) the single chromatid (chromatid translocation) or a segment of chromatid. The sites of translocations are called translocation points. The reciprocal translocation may be either asymmetrical (aneucentric) or symmetrical (eucentric).

The asymmetrical translocation gives rise to one dicentric and one acentric chromosomes (Fig. 22.10) and it may lead to the formation of chromosome bridge if the two centromeres of a dicentric translocation product are distributed to opposite poles of spindle during anaphase. In symmetrical translocation, however, the products are monocentric.

Sometime, whole or nearly whole arms of the chromosomes may be transposed or interchanged. This is termed whole-arm translocation (Muller, 1940).

There are three special cases of whole arm translocation:

Translocation occurring between two sub-telocentric chromosomes, each with sub-terminal centromere and single long arm, may exchange parts in such a way that major part of long arm of one is translocated to the short arm of the other producing one V-shaped long metacentric chromosome (i.e., with median centromere) and one small chromosome with two minute arms.

Long V-shaped chromosome has all the vital genetic material and the small chromosome is little more than a centromere plus some chromatic material.

This type of translocation is called “centric fusion” by White (1954) [Fig. 22.11 (a)]. Such a translocation may be quite viable and in a heterozygote, one long V-shaped chromosome may synapse normally with two normal unfused one armed homologous chromosomes.

The small chromosome is more or less functionless and appears like a supernumerary one which may be lost from any individual but maintained in the population. These supernumerary chromosomes are spare kinetochores.

The reverse translocation in them may lead to increase in basic chromosome number. It seems a very likely mechanism for the alteration in the chromosome number, although there is little direct evidence for it.

In general, the translocation appears to be major method of genome alteration. Thus it leads to reshuffling of genie loci as well as alterations of basic chromosome morphology. Centric fusions taking place between a sex chromosome and an autosome may represent the origin of “multiple sex chromosome” system.

Contrary to centric fusion, in dissociation one metacentric chromosome with long arms and the second metacentric chromosome with short arms after reciprocal translocation give rise to two acrocentric chromosomes [Fig. 22.11 (b)].

This results from a single break in the vicinity of centromere of one chromosome and another break near the end of a second chromosome. If the two chromosomes involved in this process are acrocentrics, then one large acrocentric and one small metacentric chromosomes will result (Figs. 22.11 (c), 22.12).

But if the interchange takes place between one metacentric and the other acrocentric chromosome, then two acrocentrics, one short and the other large may be formed [Fig. 22.11 (d)].

Translocations are usually non-lethal in their effects. Like deficiency and duplication, the translocations may also be homozygous or heterozygous provided the aberrations in question are not associated with lethality.

The homozygous translocations are characterised by the presence of same gene sequences in the transposed segments of homologous chromosomes. If an organism carrying two pairs of chromosomes with reciprocal translocation is crossed with a normal organism, the offspring will be heterozygous for translocation. Translocation heterozygotes thus possess translocated and normal chromosomes.

The following are the important effects or evidences of translocations:

1. Cytological Effects of Translocations:

The chromosomes of homozygous translocations generally behave as do the normal ones from which they arise, except that new linkage groups are formed. If they persist they can give rise to new chromosomal races in the population.

In the individuals heterozygous for a symmetrical reciprocal translocation (structural hybrids) two chromosomes with translocation and two normal chromosomes share a partial homology, but no two are identical.

Since synapsis is a matter of homologous regions (gene to gene pairing) and these regions are distributed over four chromosomes, in simple reciprocal translocation heterozygote, the association of all four chromosomes will be formed. Such an association will result in a cross configuration (+) at pachytene i.e., there will develop a group of four associated chromosomes (2 normal + 2 translocated) (Fig. 22.14).

Heterozygosity for translocation reduces the crossing over frequency. The crossing over can take place in any of the four pairing segments of cross-like configuration in reciprocal translocation heterozygote but the results will vary according to the cross over site relative to centromeres and breakpoints of the translocation.

If the crossing over occurs in the regions between the centromeres and break points (i.e., interstitial region) it will result in duplicated and deficient chromosomes irrespective of adjacent or alternate distribution patterns.

This may be major cause of sterility in translocation heterozygotes. But the crossing over appears to be restricted in the interstitial regions because of inefficient synapsis between the chromosomes. If the crossing over takes place outside the interstitial regions, it does not affect the segregation patterns since one homologous section is exchanged for another.

Reduced crossing over within the translocated part is most pronounced in the vicinity of the interchange points. It is so on account of non-homologous pairing in interchange region or due to difficulty in its meiotic chromosome pairing.

The subsequent behaviour of this cross configuration depends upon the frequency and locatior of the chiasmata and the centromere orientation. If chiasma formation takes place in all four pairing segments, a ring of four chromosomes results. The occurrence of quadrivalent rings has been observed during metaphase in Datura, peas, wheat, Tradescantia and some other plants as well as animals.

If chiasma formation fails in one of the four pairing segments, a chain of four chromosomes results. If chiasma formation takes place in two adjacent or alternate pairing segments, a chain of three chromosomes and one univalent, or two bivalents will result.

Rings and chains contain structurally normal and structurally changed chromosomes in alternating sequence. Now the distribution of the four chromosomes in ring or chain configuration at anaphase I of meiosis is determined by the orientation of centromeres. There are two common patterns of distribution, adjacent and alternate (Fig. 22.14).

(a) Adjacent distribution:

In this the chromosomes located alternately in the pairing configuration are segregated in such a way that one structurally normal and one translocated chromosome go to one pole and their counterparts, to the opposite pole. In this case both meiotic products are duplicated.

In adjacent distribution there are two events:

(i) Adjacent 1 distribution in which the centromeres of neighbouring non-homologous chromosomes segregate to same pole, and

(ii) Adjacent-2 distribution in which homologous centromeres migrate to the same pole, but it is very rare in occurrence.

(b) Alternate distribution:

In this the two normal chromosomes go to one pole and the two translocated chromosomes go to the opposite pole during anaphase I and so the gametes- formed are of two kinds some with normal chromosomes and some with translocated chromosomes.

Multiple Translocation System:

If the arm of one of the two translocated chromosomes is involved in a second interchange with a third non-homologous chromosome, a ring of 6 chromosomes (Fig. 22.15) may be formed at metaphase I. In the same way, a third interchange would give rise to a ring of 8 chromosomes.

This process can go on until the entire complement of chromosomes is involved. This produces a translocation complex or complex heterozygote.

In Rhoeo spathacea all 12 chromosomes are involved in reciprocal translocations and as a result of this a ring of 12 chromosomes is formed during meiosis. Oenothera exhibits a similar tendency which varies with the species.

In O. hookeri normally 7 bivalents are formed but in other species formation of multivalent ring and bivalents may be observed and in some other species, such as O. lamarkiana all fourteen chromosomes are linked to form a ring at metaphase I. Translocation complexes of the types described in Rhoeo and Oenothera are not known in animals.

Similar situation has been reported in several other plants exposed to X-rays, gamma-rays and mutagenic chemicals.

2. Genetic Effects of Tanslocations:

The main genetic effects of translocations are as follows:

(i) It brings about a qualitative change in the chromosomes structure or linkage group,

(ii) It brings about change in the sequences of genes in chromosomes which may eventually produce several abnormalities in body characters. This is position effect.

(iii) Semi-sterility. The translocation heterozygotes are generally semi-sterile because they produce gametes containing duplicated and deficient chromosomes as a result of typical pairing behaviours, crossing over and segregation patterns of chromosomes.

The translocation is of great importance for the individuals and the species. The most harmful effect of a reciprocal translocation is the semi-sterility it causes. It also causes severe modifications of the normal developmental pattern.

In the evening primrose (Oenothera) a number of variations are associated with translocations. This was the plant whose variability led De Vries to propose his popular mutation theory.

Chromosomal Aberration: Type # 4. Inversion:

I”, is an intrachromosomal aberration characterised by inversion or reversal of a chromosome segment and the gene sequence contained therein relative to the standard chromosome or linkage group in question. It occurs in intercalary segment of the chromosome. There is no experimental evidence for occurrence of inversions in terminal segments of chromosomes.

According to the breakage reunion —model, the intercalary inversions are formed when two breaks occur in a chromosome, the middle segment between the break points (referred to as inversion points) is inverted or rotated through : and then reunion of the three segments at the sites of breakage takes place as shown below Fig. 22.16).

Sometimes inverted segment or a part of it may again undergo inversion. This is called included inversion. Thus, in the above example, if the segment, GFEDC in the inverted chromosome undergoes further inversion, the result will be that the chromosome will regain original gene sequence ABCDEFGHIJ.

Types of Inversions:

The inversions are classified according to the number of inverted segments within the chromosome and the location of inversion points with respect to each other.

When a chromosome contains a single inverted segment, it is called single inversion. Single inversions are classified according to whether or not the inverted segment of the chromosome carries the centromere.

(i) Paracentric inversion. This is the most common type of inversion which is confined to a single arm of a chromosome. In this, the inverted segment of the chromosome does not carry centromere. It is also called acentric or dyscentric orparakinetic or asymmetrical inversion (Fig. 22.17).

(ii) Pericentric inversion:

In this type of inversion, the break points are located in both the arms of chromosome so that the inverted segment includes centromere (Fig. 22.17). It is also called transcentric or eucentric or transkinetic or symmetrical inversion. If the two breakpoints involved in the formation of a pericentric inversion are equidistant from the centromere, the inverted chromosome will appear morphologically similar to normal one.

But, if the breakpoints are asymmetric (not equidistant) from the centromere, a shift of centromere from acrocentric to metacentric or vice-versa may occur, thus causing a marked change in the appearance of chromosome. This indicates that pericentric inversions might have played important role in the evolution of new karyotypes.

When a chromosome contains more than one inverted segment, it is called complex inversion.

The complex inversions are classified as follows:

(i) Independent inversion:

When the inverted segments are separated from one another by uninverted segment, the inversion is said to be independent inversion.

Inversions may be either homozygous or heterozygous. Homozygous inversions have homologous chromosomes with identical inversions. They show normal meiotic pairing and distribution. Heterozygous inversions have one homologue with inversion and the other homologue without inversion (i.e., normal).

Inversion heterozygotes show important cytological and genetic effects. Because there is no net loss or gain of genetic material, inversion heterozygotes are perfectly viable. The pairing behaviour of inversion chromosome with standard or non-inverted homologue depends on the length of inversion and the longitudinal relationship of the inverted and uninverted chromosome segments.

If the inversion is long, chromosome pairing involves formation of characteristic loop in the normal homologous chromosome and the inversion chromosome pairs with the normal chromosome in such a way that homologous loci pair with each other. The location of the inverted segment, thus, can be recognised cytologically by the presence of an inversion loop in the paired homologues during meiosis.

If the inverted segment is so small that loop formation is not possible either the inverted segment is left unpaired or it may pair with non-homologous segment of normal chromosome. The size of the loop is a function of the size of the inversion—the larger is the inversion, the larger will be the loop.

The crossing over and chiasma formation within and outside inversion loop give rise to secondary structural changes (duplication and deletion) depending upon the type of inversion (paracentric or pericentric), the number of chiasmata and localization of chiasmata. Such structural changes result in meiotic products with unbalanced sets of chromosomes.

Single crossing over within a pericentric heterozygous inversion produces two normal meiotic products and two abnormal products—containing chromosom that are either duplicated or deficient for certain gene loci a (Fig. 22.18 B).

In plants gametes containing duplication or deficiency are generally not viable. So, pericentric inversion heterozygotes are semi-sterile, although more than 50% viable. In animals, the gametes with duplication and deficiency in chromosomes are usually normal in function, but zygote usually does not survive.

Single crossing over within a paracentric inversion has more complex consequences and it produces one chromosome with two centromere (dicentric chromosome) and one with no centromere (acentric chromosome segment).

During anaphase 1 of meiosis dicentric chromosome is pulled as a bridge between two spindle poles and acentric chromosome, because it has no spindle fibre attachment, floats randomly as laggard and is eventually lost (Fig. 22.18 A).

The dicentric bridge may break at any point giving rise to duplications and deficiencies in the meiotic products. Remarkably, in Drosophila and plant egg cells, the dicentric bridge may remain intact long after anaphase I. Thus, the two daughter nuclei either will be linked by dicentric bridge or will contain the fragments of the bridge if it breaks.

The fragment associated with the bridge has the effect of a deficiency and the size of deficiency determines the reduction in fertility. That is, a meiotic product or gamete lacking in one or more genes because of the loss of a segment of chromosome is likely to be non-viable and hence sterile.

In general, females heterozygous for paracentric inversion manifest no serious sterility because in most cases the chromosomes are oriented in specific direction during gametogenesis which facilitates exclusion of dicentric and acentric chromosomes from functional gametes.

When two cross overs are formed within inversion loop, the result will depend upon the number of chromatids involved. Two strand-double crossing over will yield four normal chromatids, two of which will be involved in crossing over and the other will were not. Such a condition can be detected only when appropriate genetic markers are present within the region of crossing over.

Three-strand double crossing over will yield one non-cross over chromatid, one cross-over chromatid and two acentric fragments. Four-strand double cross-over would yield two dicentric chromatids and two acentric fragments and deficiency and duplication would presumably lead to in-viability of the meiotic products or gametes or would cause death of zygote or embryo if such gametes were involved in fertilization.

It is, therefore, evident that paracentric inversions have a drastic effect on the recovery of chromatids involved in crossing over.

Another major effect of inversions is to suppress the recombination of genie loci by crossing over to maintain in the population a specific segment of a chromosome.

Crossing over does occur within the inversion, but the crossing over products do not usually contribute to the next generation either because the gametes or zygotes are inviable or because the cross over chromosomes are eliminated from non-functional megaspore in plants or polar bodies in the animals.

The presence of recessive lethal gene within inverted segment can be of added advantage in preserving structural heterozygosity because heterozygotes for lethal recessive genes will be viable and homozygous, non­viable.

In CIB stock of Drosophila, C factor which is a cross-over suppressor is found to be inverted segment of chromosome, 1 component, a recessive lethal, prevents homozygosity for CIB chromosome and B gene accounts for bar eye.

In CIB chromosome C factor is flanked on either side by two marker genes 1 and B. Muller (1928) was the first to take advantage of cross-over suppressing property o inversion heterozygote to detect sex-linked recessive lethal mutations in Drosophila induced by X rays.

The genetic evidence of inversion thus will be:

(i) Suppression of crossing over, and

(ii) Possibly the appearance of mutation owing to position effect.

As mentioned earlier, inversion and translocation involve no loss or gain in the genes as such. Simply they bring about change in the position of some genes and no gene mutation (i.e., no change in the nature of gene) is involved in these cases.

The changed positions of genes in the chromosomes may have important consequences since continuous genes sometimes are concerned in the completion of related steps of some repetition biochemical reactions. All such alterations of gene functions due to change in the sequence of genes are referred to as “position effects”.

Inversion homozygotes can be detected cytologically and genetically in the following ways:

(i) By detecting changed linkage relation with the help of genetic linkage studies,

(ii) By detecting the changes in chromosome morphology during mitotic metaphase.

(iii) By observing the changes in chromosome bands.

The inversion heterozygotes are detected by the following characteristics:

(i) Formation of inversion loop during the prophase I of meiosis.

(ii) Formation of dicentric chromosomal bridge, acentric fragments during anaphase I.

(iii) Development of abnormal meiotic products which may be detected by means of tetrad analysis.

(iv) Decreased fertility resulting due to production of genetically unbalanced meiotic products or gametes via crossing over.

Exclusive: ICE to Release Migrants Further into U.S. — Away from Texas Border Cities

33,252 File Photo: LOREN ELLIOTT/AFP via Getty Images

Federal law enforcement sources report that Border Patrol agents will now rely on Immigration and Customs Enforcement (ICE) officers to conduct migrant releases when detention space is not available in the Texas Rio Grande Valley. Migrant releases coordinated specifically by Border Patrol directly into border communities will be a last-resort option. Border Patrol officials are instructed to conduct the local releases only when ICE cannot cope with the level of arrests made by the Border Patrol.

The new policy may bring some relief to local shelters in South Texas border communities located in the Rio Grande Valley depending on where ICE Enforcement and Removal Operations officials choose to release the migrants. The change in procedure is likely driven by increased media attention to the issue. It will likely result in migrants being released away from border communities in the Rio Grande Valley.

According to sources familiar with the new policy, ICE will transport many of the released migrants away from the immediate border region to family residential detention centers to await release. If this occurs, it will require significant funding for transportation costs associated with the movement of migrants to other cities.

Family residential detention centers operated by ICE are in smaller Texas communities surrounding San Antonio with insufficient public transportation resources to move the migrants. Sources tell Breitbart News this increases the likelihood that migrant releases will increase in San Antonio. The move is largely designed to change the current optics of where migrants are released. It is unlikely to impact the increased flow of arriving migrants.

As reported by Breitbart News, the ill-timed migrant releases before the winter storm were an ominous sign for border communities. Many lacked sufficient resources to deal with hundreds of released migrants. According to law enforcement sources, COVID-19 testing of released migrants is still not happening in many border communities.

During the cold snap in Texas, humanitarian shelters along the border quickly filled as transportation companies shut down operations. In some cases, migrants turned to local businesses for warmth as power failed at non-government humanitarian shelters. Residents in one Texas border community reported seeing migrants wandering through large department stores where, fortunately, power and heat were still available during the crisis.

Mayor Bruno Lozano of Del Rio, Texas, posted a YouTube video strongly urging President Biden to halt migrant releases within his city and surrounding communities. In the video, Mayor Lozano highlights the devastating conditions caused by recent freezing weather and the lack of available resources to cope with the released migrants. He raises COVID-19 concerns within the community and pleads for sufficient resources to address the influx of migrants.

Although little has changed regarding the situation in West Texas, law enforcement sources indicate the message may have resonated elsewhere as the new practices regarding how migrants are released in the Rio Grande Valley suddenly changed.

The volume of arrests within the Rio Grande Valley will determine how long the new plan remains in effect. According to CBP, Border Patrol agents in the Rio Grande Valley arrested more than 69,000 migrants since the start of this fiscal year, which began in October 2020, through January. Compared to the same time frame last fiscal year, the increase in arrests is a staggering 136 percent.

Breitbart News reached out to ICE officials for additional information about the policy change. A response was not available by press time.

Randy Clark is a 32-year veteran of the United States Border Patrol. Prior to his retirement, he served as the Division Chief for Law Enforcement Operations, directing operations for nine Border Patrol Stations within the Del Rio, Texas Sector.

Additional Bed Bug Information & Statistics

  • Bed bugs can lay one to five eggs in a day and more than 500 in a lifetime.
  • Bed bugs can survive for several months without eating.
  • Bed bugs can withstand a wide range of temperatures, from nearly freezing to 122 degrees Fahrenheit.
  • Bed bug draw blood for about five minutes before retreating to digest.
  • Bed bugs hatchlings are so small they can pass through a stitch-hole in a mattress.
  • Bed bugs can ingest seven times their own weight in blood, which would be the equivalent of an average-sized male drinking 120 gallons of liquid.
  • Bed bugs are found in all 50 U.S. states.

History of Bed Bugs

Learn about the history of bed bugs and the factors that lead to their resurgence.

Bed Bug Biology

Learn about the biology of bed bugs - from their shape and size to their life cycle and feeding habits.

Location of Bed Bugs

Wondering where bed bugs are found? Discover common bed bug habitats and infestation regions.

Signs of Bed Bugs

Learn about the common signs of bed bugs - from bites on the skin to spots on the mattress to sticky eggs.

Bed Bug Prevention

Learn about bed bug prevention at home and how to avoid bed bugs when traveling with our helpful tips.


The box-sizing property in CSS controls how the box model is handled for the element it applies to.

One of the more common ways to use it is to apply it to all elements on the page, pseudo elements included:

This is often called “universal box-sizing”, and it’s a good way to work! The (literal) width you set is the width you get, without having to perform mental math and manage the complexity that comes from widths that come from multiple properties. We even have a box-sizing awareness day around here.

  • content-box : the default. Width and height values apply to the element’s content only. The padding and border are added to the outside of the box.
  • padding-box : Width and height values apply to the element’s content and its padding. The border is added to the outside of the box. Currently, only Firefox supports the padding-box value.
  • border-box : Width and height values apply to the content, padding, and border.
  • inherit : inherits the box sizing of the parent element.

This example image compares the default content-box (top) to border-box (bottom):

The red line between the images represents the elements’ width value. Notice that the element with the default box-sizing: content-box exceeds the declared width when the padding and border are added to the outside of the content box, while the element with box-sizing: border-box applied fits completely within the declared width.

Let’s say you set an element to width: 100px padding: 20px border: 5px solid black . By default, the resulting box is 150px wide. That’s because the default box sizing model is content-box , which applies an element’s declared width to its content only, placing the padding and border outside the element’s box. This effectively increases how much space the element takes up.

If you change the box-sizing to padding-box , the padding is pushed inside the element’s box. Then, the box would be 110px wide, with 20px of padding on the inside and 10px of border on the outside. If you want to put the padding and the border inside the box, you can use border-box . The box would then be 100px wide &mdash the 10px of border and 20px of padding are both pushed inside the element’s box.

&dagger older versions require -webkit prefix (Chrome 1-9, Safari 3-5, Android 2.1-3.x)

Before diving into an analysis, it’s worth touching on the methodology behind this graphic’s design.

This map highlights thousands of the world’s most popular websites by visualizing them as “countries.” These “countries” are organized into clusters that are grouped by their content type (whether it’s a news website, search engine, e-commerce platform, etc).

Editor’s fun fact: Can you spot Visual Capitalist? We’re right in between TechCrunch and The Guardian above.

The colored borders represent a website’s logo or user interface. In terms of scale, each website’s territory size is based on its average Alexa web traffic ranking. The data is a yearly average, measured from January 2020 to January 2021.

Along the borders of the map, you can find additional information, from ranked lists of social media consumption to a mini-map of average download speeds across the globe.

According to the designer Martin Vargic, this map took about a year to complete.

Factors Affecting Enzyme Activity: 6 Factors

This article throws light upon the six factors affecting the enzyme activity.

The six factors are: (1) Concentration of Enzyme (2) Concentration of Substrate (3) Effect of Temperature (4) Effect of pH (5) Effect of Product Concentration and (6) Effect of Activators.

The contact between the enzyme and substrate is the most essential pre-requisite for enzyme activity.

The important factors that influence the velocity of the enzyme reaction are discussed hereunder:

Factor # 1. Concentration of Enzyme:

As the concentration of the enzyme is increased, the velocity of the reaction proportionately increases (Fig. 66.1). In fact, this property of enzyme is made use in determining the activities of serum enzymes for diagnosis of diseases.

Factor # 2. Concentration of Substrate:

Increase in the substrate concentration gradually increases the velocity of enzyme reaction within the limited range of substrate levels. A rectangular hyperbola is obtained when velocity is plotted against the substrate concentration (Fig. 66.2). Three distinct phases of the reaction are observed in the graph.

Enzyme kinetics and Km value:

The enzyme (E) and substrate (S) combine with each other to form an unstable enzyme-substrate complex (ES) for the formation of product (P).

Here k1, k2 and k3 represent the velocity constants for the respective reactions, as indicated by arrows.

Km, the Michaelis-Menten constant (or Brig’s and Haldane’s constant), is given by the formula

The following equation is obtained after suitable algebraic manipulation.

where v = Measured velocity,

S = Substrate concentration,

Km = Michaelis-Menten constant.

Km or the Michaelis-Menten constant is defined as the substrate concentration (expressed in moles/lit) to produce half-maximum velocity in an enzyme catalysed reaction. It indicates that half of the enzyme molecules (i.e. 50%) are bound with the substrate molecules when the substrate concentration equals the Km value.

Km value is a constant and a characteristic feature of a given enzyme. It is a representative for measuring the strength of ES complex. A low Km value indicates a strong affinity between enzyme and substrate, whereas a high Km value reflects a weak affinity between them. For majority of enzymes, the Km values are in the range of 10 -5 to 10 -2 moles.

Line weaver-Burk double reciprocal plot:

For the determination of Km value, the substrate saturation curve (Fig. 66.2) is not very accurate since Vmax is approached asymptotically. By taking the reciprocals of the equation (1), a straight line graphic representation is obtained.

The Line weaver-Burk plot is shown in Fig. 66.3. It is much easier to calculate the Km from the intercept on x-axis which is -(1/Km). Further, the double reciprocal plot is useful in understanding the effect of various inhibitions.

Factor # 3. Effect of Temperature:

Velocity of an enzyme reaction increases with increase in temperature up to a maximum and then declines. A bell-shaped curve is usually observed (Fig. 66.4).

The optimum temperature for most of the enzymes is between 40°C-45°C. However, a few enzymes (e.g. venom phosphokinases, muscle adenylate kinase) are active even at 100°C. In general, when the enzymes are exposed to a temperature above 50°C, denaturation leading to derangement in the native (tertiary) structure of the protein and active site are seen. Majority of the enzymes become inactive at higher temperature (above 70°C).

Factor # 4. Effect of pH:

Increase in the hydrogen ion concentration (pH) considerably influences the enzyme activity and a bell-shaped curve is normally obtained (Fig. 66.5). Each enzyme has an optimum pH at which the velocity is maximum.

Most of the enzymes of higher organisms show optimum activity around neutral pH (6-8). There are, however, many exceptions like pepsin (1-2), acid phosphatase (4-5) and alkaline phosphatase (10-11) for optimum pH.

Factor # 5. Effect of Product Concentration:

The accumulation of reaction products generally decreases the enzyme velocity. For certain’ enzymes, the products combine with the active site of enzyme and form a loose complex and, thus, inhibit the enzyme activity. In the living system, this type of inhibition is generally prevented by a quick removal of products formed.

Interactive Monarch Migration

Click on the seasons on the right for an interactive view of the monarchs' annual migration. When each animation is finished, click on the butterfly to learn more with videos and slide shows.

Go to full screen version

This map was created in collaboration with the Center for Global Environmental Education at Hamline University with generous support from US Forest Service - International Programs, US Fish and Wildlife Service, and Missouri Department of Conservation.

Eastern Monarchs

Decreasing day length and temperatures, along with aging milkweed and nectar sources trigger a change in monarchs this change signifies the beginning of the migratory generation. Unlike summer generations that live for two to six weeks as adults, adults in the migratory generation can live for up to nine months. Most monarch butterflies that emerge after about mid-August in the eastern U.S. enter reproductive diapause (do not reproduce) and begin to migrate south in search of the overwintering grounds where they have never been before. From across the eastern U.S. and southern Canada, monarchs funnel toward Mexico. Along the way, they find refuge in stopover sights with abundant nectar sources and shelter from harsh weather. Upon reaching their destination in central Mexico beginning in early November, monarchs aggregate in oyamel fir trees on south-southwest facing mountain slopes. These locations provide cool temperatures, water, and adequate shelter to protect them from predators and allow them to conserve enough energy to survive winter. In March, this generation begins the journey north into Texas and southern states, laying eggs and nectaring as they migrate and breed. The first generation offspring from the overwintering population continue the journey from the southern U.S. to recolonize the eastern breeding grounds, migrating north through the central latitudes in approximately late April through May. Second and third generations populate the breeding grounds throughout the summer. It is generally the fourth generation that begins where we started this paragraph, migrating through the central and southern U.S. and northern Mexico to the wintering sites in central Mexico.

Western Monarchs

Western monarchs gather to roost in eucalyptus, Monterey cypress, Monterey pine, and other trees in groves along the Pacific coastline of California, arriving beginning in late October. The climate of these locations is very similar to that of the Mexico overwintering locations. The colonies generally break up slightly earlier than those in Mexico, with dispersal generally beginning in mid-February. Less is known about the timing and location of breeding and migratory movement in the western US, but milkweed and nectar plant availability throughout the spring, summer and fall will benefit western monarchs, especially in California, Nevada, Idaho, and Oregon, states that appear to be important sources of western monarchs. In areas of the desert southwest, monarchs use nectar and milkweed plants throughout much of the year. For western monarch information and resources, visit the Western Monarchs category of our Downloads and Links page.

How do monarchs find the overwintering sites?

Orientation is not well understood in insects. In monarchs, orientation is especially mysterious. How do millions of monarchs start their southbound journey from all over eastern and central North America and end up in a very small area in the mountains of central Mexico? We know that they do not learn the route from their parents since only about every fifth generation of monarchs migrates. Therefore, it is certain that monarchs rely on their instincts rather than learning to find overwintering sites. What kind of instincts might they rely on? Other animals use celestial cues (the sun, moon, or stars), the earth&rsquos magnetic field, landmarks (mountain ranges or bodies of water), polarized light, infra-red energy perception, or some combination of these cues. Of these, the first two are considered to be the most likely cues that monarchs use, and consequently have been studied the most.

Sun Compass: Since monarchs migrate during the day, the sun is the celestial cue most likely to be useful in pointing the way to the overwintering sites. This proposed mechanism is called a sun compass. Monarchs may use the angle of the sun along the horizon in combination with an internal body clock (like a circadian rhythm) to maintain a southwesterly flight path. The way this would work is illustrated below. For example, if a monarch&rsquos internal clock reads 10:00 AM, then the monarch will fly to the west of the sun to maintain a southern flight direction. When the monarch&rsquos internal clock reads noon (12:00 PM), the monarch&rsquos instincts tell it to fly straight toward the sun, while later in the day the monarch&rsquos instincts tell it to fly to the east of the sun.

However, this would have to be combined with the use of some other kind of cue. If all the monarchs in eastern and central North America maintained a southwesterly flight, they could never all end up in the same place. It has been proposed that mountain ranges are important landmarks used by monarchs during their migration. For example, when eastern monarchs encounter a mountain range, their instincts might tell them to turn south and follow the mountain range. This kind of instinct would serve to funnel monarchs from the entire eastern half of North America to a fairly small region in the mountains of central Mexico.

Magnetic Compass: Scientists have suggested that monarchs may use a magnetic compass to orient, possibly in addition to a sun compass or as a &ldquoback-up&rdquo orientation guide on cloudy days when they cannot see the sun. Studies of migratory birds have indicated that they register the angle made by the earth&rsquos magnetic field and the surface of the earth. These angles point south in the Northern Hemisphere and north in the Southern Hemisphere.

James Kanz (1977) conducted experiments to test the orientation of migratory monarchs held in cylindrical flight chambers. He reported that the monarchs flew in southwesterly directions on sunny days, but flew in random directions on cloudy days. He concluded that monarchs primarily use the sun to orient, and that magnetic orientation was unlikely, since the monarchs did not appear to be able to orient when they could not use the sun. However, Klaus Scmidt-Koenig (1985) reported conflicting evidence. He recorded the vanishing bearings (the direction in which a monarch disappears from sight) of wild, migratory monarchs, and found that even on cloudy days, most monarchs still flew in a southwesterly direction. Scientists attempted additional tests of magnetic orientation, but were not able to determine whether monarchs use the Earth&rsquos magnetic field to orient.

However, researchers from the Reppert Lab (2014) showed that migratory monarchs indeed possess a magnetic compass that aids in orienting migrants south towards their overwintering grounds during fall migration. Remarkably, the use of the magnetic compass requires short wave UV-light (previous magnetic compass experiments failed to account for light at this range). With UV-light being allowed to enter the flight simulator, eastern migratory monarchs consistently oriented themselves south. The light-sensitive magnetosensors reside in the adult monarch&rsquos antennae. While the expert consensus remains that the sun compass is the monarch&rsquos primary compass for navigation, the authors suggest migratory monarchs use the magnetic compass to augment their sun compass.

Genetics: Upon dispersal, the Central and South American, Atlantic, and Pacific populations lost the ability to migrate. This prompted researchers to identify the gene regions in North American monarchs that appeared highly differentiated from non-migratory populations. Kronforst et al. (2014) identified 536 genes significantly associated with migration. One single genomic segment appeared to be divergent in the non-migrating populations and was extremely different from the North American population. One gene, collagen IV alpha-1, showed high divergence between migrating and non-migrating populations. Collagen IV alpha-1 is an important gene for muscle function, and divergence of this gene implicates selection for different flight muscles between migrating and non-migrating populations. Surprisingly, Collagen IV alpha-1 was down regulated in migratory monarchs, perhaps preparing them for lengthy flight. Furthermore, migrating monarchs had low metabolic rates compared to non-migrants as a consequence of flight muscle performance, lowering energy expenditure in migrating monarchs muscles. This evidence led researchers to conclude that changes in muscle function afforded migrating monarchs the ability to fly farther and use their energy more efficiently. Dr. Kronforst used the analogy of a marathon runner vs. a sprinter, "Migrating butterflies are essentially endurance athletes, while others are sprinters."

Journey North provides an excellent tutorial of how monarchs orient themselves during their migration.

Primary Sources

(1) Manchester Guardian (22nd October, 1914)

Victory on the Allied left in Northern France and West Flanders is confidently expected by the troops. From many quarters come reports of the high hopes entertained by the armies. Apparently the fighting is going well and the German position becoming increasingly unfavourable. Throughout yesterday the enemy vigorously attacked the Allied front, only to be beaten back after suffering heavy losses. These tactics are one more proof of the pressure under which the Kaiser's armies are giving way.

The generals are evidently doing their utmost to check the Allies, but of a genuine offensive there is no sign. About Nieuport, on the Belgian coast, where the Allied front reaches the sea, the British navy has lent the armies valuable aid. Three heavily armed monitors, bought by the Admiralty from Brazil, for whom they were completing in England when war broke out, steamed in close to the shore, and by shelling the German flank powerfully assisted the Belgian troops.

Machine guns were landed at Nieuport, and by that means also the navy reinforced the defence. The seaward flank is attracting much of the enemy's attention. Yesterday, says the Paris official statement, the battle was violent between La Bassee and the coast, but nowhere did the Germans obtain any success.

Russia is more than holding her own. Petrograd, which has been studiously moderate in its reports about the fighting in Poland, now announces a German retreat from before Warsaw. The enemy are falling back utterly routed. It has been obvious for several days that Germany's first effort to force a way over the Vistula had failed the failure now appears to have been costly.

Russia's claims find unwilling support in the Berlin wireless circular, which has taken to announcing "no result" and "no change" on the Polish front. Germany will find herself faced with disaster if Russia is able to continue her good work and beat General von Hindenburg's main army as she has beaten his advanced troops.

(2) Manchester Guardian (28th October, 1914)

On the sea flank of the Franco-Belgian front Germany strives desperately to break her way through to the cost. Report says the Kaiser has ordered his generals to take Calais no matter what the cost.

Already the cost of the effort has been terrible, and the taking promises to be long deferred. A Paris official statement issued yesterday afternoon said the enemy were held everywhere, while between Ypres and Roulers the Allied troops had made progress. The British are fighting in front of Ypres.

Berlin puts the best possible construction on events but cannot pretend to a victory, and has to content itself with announcing minor advances. Germany's dash for the coast has suffered many delays, and now seems to have failed. How heavy the enemy's losses have been is illustrated by an incident mentioned in a despatch from an "Eye-witness present with General Headquarters."

On Tuesday, October 20, a determined but unsuccessful attack was made on virtually the whole British line, and at one point where one of our brigades made a counter-attack 1,100 Germans were found dead in a trench and 40 prisoners were taken. Everywhere the British troops have fought with the most splendid courage. For five days at Ypres they held in check, although overwhelmingly outnumbered, 250,000 Germans who fought recklessly to break a way through.

Russia expects great things from her campaign in Western Poland, so well begun with the repulse of the Germans from before Warsaw. The enemy's left flank has been pushed back far towards the frontier while their right remains near the Middle Vistula. This position would be difficult for the Army holding it in the best circumstances. It has been made dangerous by Russian enterprise.

A strong cavalry force has pushed rapidly westwards to Lodz, and from there threatens the German rear. About Radom, on their advanced right, the enemy have prepared a defensive line, but they can hardly remain in possession while danger draws near from Lodz. On the Vistula, east of Radom, the Russians have taken 3,000 prisoners, cannon, and machine guns.

Borderline Personality Test

This test is designed to help you understand whether you may have Borderline Personality Disorder. Borderline personality disorder is a mental health condition characterized by a person who has a difficult time maintaining long-term interpersonal relationships due to the way they process their emotions and feelings.

This online screening is not a diagnostic tool. Only a trained medical professional, like a doctor or mental health professional, can help you determine the next best steps for you.

“Borderline” means to be in-between one thing and another. And that perfectly describes a person with this disorder, as they ping-pong back and forth between relationships, emotions, and their view of themselves.

The symptoms of borderline personality disorder (BPD) are characterized by a long-standing pattern of unstable relationships, an effort to avoid abandonment, and impulsivity in decision-making. People with this condition often swing between emotions easily, which directly impacts their relationships with others and their own self-image.

As with most personality disorders, these are long-standing, intractable patterns of behavior and thoughts. Most people don’t see out treatment for BPD directly, but rather will present at times during emotional or life turmoil as a result of their symptoms.

Living with BPD

Since BPD is often a life-long condition, it’s important for people to learn ways that can help them best manage the symptoms associated with the diagnosis. That means not only engaging in treatment, but making a commitment to engaging in life changes to help a person reduce the symptom intensity or duration. Most people with BPD can find a way to live successfully with this disorder, but it may take some time for a person to find the right treatment provider and have the adequate motivation needed to change.

Treatment of Borderline Personality Disorder

Treatment for BPD is available and effective. The most common type of treatment is a form of psychotherapy called dialectical behavior therapy (DBT). This has been shown to be an effective intervention in dozens of scientific studies, and is well-tolerated by most people who give it a try.

The treatment approach consists of individual therapy, group skills training, and phone (or online) coaching. It’s a weekly commitment of 2-4 hours every week, which tends to be a bit more than traditional psychotherapy approaches.

Watch the video: Geschwindigkeit berechnen nur kmh. Mathematik. Lehrerschmidt - einfach erklärt! (September 2022).


  1. Carswell

    Of course. I subscribe to all of the above. Let's discuss this issue. Here or at PM.

  2. Jussi

    I must tell you that you are wrong.

Write a message