Persius/hicric huggingface dataset:
Bertolotti's syndrome
Bertolotti's syndrome is a form of lumbago in the lumbosacral transitional vertebrae. The syndrome is not usually treated, as not much is known yet about these spinal segments.

# Etymology
It is named after Mario Bertolotti, an Italian physician 

# Pathophysiology
Bertolotti's syndrome is defined by a transitional 5th lumbar vertebra resulting in partial sacralization. Of importance is that this syndrome will result in a pain generating 4th lumbar disc resulting in a "sciatic" type of a pain correlating to the 5th lumbar nerve root.
Usually the transitional vertebra will have a "spatulated" transverse process on one side resulting in articulation or partial articulation with the sacrum or at time the ilium and in some cases with both. This results in limited / altered motion at the lumbo-sacral articulation. This loss of motion will then be compensated for at segments superior to the transitional vertebra resulting in accelerated degeneration and strain through the L4 disc level which can become symptomatic and inflame the adjacent L5 nerve root resulting in "sciatic" or radicular pain patterns. This is a congenital condition and is usually not symptomatic until one's later twenties or early thirties, yet there are cases found where Bertolotti's is symptomatic at a much earlier age.
Bifunctional catalyst
A catalyst with two contrasting functional components often a Lewis acid and Lewis base.

# Overview
The broadest description of the most common definition of a bifunctional catalyst is a catalyst that contains Lewis acidic and Lewis basic component.  This definition describes bifunctionality as a form of amphoterism.  At times it more convenient to describe the catalyst as containing an electrophilic and nucleophilic, however, this description is arguably just a different phrasing of the first definition.  Other times its more convent to be more specific with the description of the contrasting groups. For example bifunctional hydrogenation catalyst contain a positions which can accept and donate a proton and another which can accept and donate a hydride.  Starting from the oxidized form of the catalysts the proton acceptor is a Lewis base and the hydride acceptor is a Lewis acid.
Many enzymes are believed to be bifunctional applying Lewis acids and Lewis bases to substrate as required for the given transformation.
Bifunctional catalysts have been used to facilitate a variety or reactions.  As already noted common examples include hydrogenation and transfer hydrogenation catalyst.  These catalysts are especially good at delivering hydrogen to unsaturated polar bonds such as ketones.  In this process the oxygen atom receives a proton and the partial positive carbon alpha to the oxygen receives a hydride.  In direct hydrorgenation hydrogen is used as the reducing agent.  In transfer hydrogenation the hydrogen is is derived from a sacrificial alcohol such as isopropanol which delivers a hydrogen equivalent to the catalysts and in the process produces acetone.  A number of these catalysts can preform the hydrogengenation enantioselectively producing chiral alcohols.

# Bifunctional Hydrogenation Mechanisms
The Shvo catalyst has been studied exstensively and is believed to deliver hydrogen through a concerted mechanisms.  Other catalysts do not deliver hydrogen through a concerted pathway but still retain the identity of the hydride.     This pathway if sometimes refereded to as the monohydride pathway.  This can be contrasted with the dihydride pathway more common in hydrogenation catalysts which are not bifunctional.  .    In theres systems the hydride and proton lose their respective identities and are ] in the hydrogenated product.
The concept of bifunctional catalyst has not been limited to a transition metal hydride acceptors.  There is also examples of using boron as a hydride acceptor for the metal free cleavage of hydrogen and hydrorgonenation of easily reduced polar unsaturated bonds such as imines.
Bifuntional hydrogenation catalysts are not limited to hydrogenation chemistry.  A number of such systems have been previously studied as hydrogenation catalysts have been found to have application in the oxidation and possibly the production in of hydrogen.  Other bifunctional catalysts have been developed for the express purpose of their elctrochemistry and associated interactions with hydrogen.
Binary ionic compound
A binary ionic compound is a salt consisting of only two elements in which both elements are ions, a cation and an anion. When naming these compounds, its composition must be considered. Type 1 binary ionic compounds are those in which the cation has only one form, or charge.  Type 2 binary ionic compounds are those in which the cation can have multiple forms. Additionally, binary ionic compounds containing polyatomic ions have another distinct set of naming rules.
Naming Type I Binary Ionic compounds (metal and nonmetal):
The metals used have to be from Group 1, 2, or Al3+, Zn2+, Ag+.
1. The cation (which is a metal in most cases) is listed first and the anion (which is a nonmetal in most cases) second
2. The cation takes the name of its elemental form. For example, Li+ would be called "Lithium".
3. The anion name uses the first part of its elemental name, and subsequently adding the suffix "-ide". For example, Br- would be called "Bromide"
Naming Type II Binary Ionic compounds (metal and nonmetal):
Metals used are transition metals except for Al3+, Zn2+, Ag+.
1. The steps follow those of Type 1 Binary Ionic compounds however, since the cation can take on multiple charges, the charge must be written within parentheses in Roman numerals after stating the cation name.
Note that there is another way to name Type 2 ionic compounds that is not as common. This involves using an alternate, Latin name for the cation.
Common Type 2 cation include Iron, Copper, Cobalt, Tin, Lead, and Mercury.
Naming Binary Compounds with Polyatomic Ions:
1. The cation is listed first and the anion second.
2. The polyatomic ion names must be memorized.
3. No extra suffixes are added.
Biological life cycle

# Overview
A life cycle is a period involving 1 generation of an organism through means of reproduction, whether through asexual reproduction or sexual reproduction. In regard to its ploidy, there are 3 types of cycles:
- haplontic life cycle
- diplontic life cycle
- diplobiontic life cycle (also referred to as diplohaplontic, haplodiplontic, or dibiontic life cycle)
These three types of cycles feature alternating haploid and [[allgerminates. To return to a haploid stage, meiosis must occur (see Cell division). The cycles differ in the product of meiosis, and wether mitosis (growth) occurs. Zygotic and gametic meioses have one mitotic stage and form: during the n phase in zygotic meiosis and during the 2n phase in gametic meiosis. Therefore, zygotic and gametic meiosis are collectively term haplobiontic (single mitosis per phase). Sporic meiosis, on the other hand, has two mitosis events (diplobiontic): one in each phase.

# Haplontic life cycle
A zygotic meiosis is a meiosis of a zygote immediately after karyogamy, which is the fusion of two cell nuclei. This way, the organism ends its diploid phase and produces several haploid cells. These cells divide mitotically to form either larger, multicellular individuals, or more haploid cells. Two opposite types of gametes (e.g., male and female) from these individuals or cells fuse to become a zygote.
In the whole cycle, zygotes are the only diploid cell; mitosis occurs only in the haploid phase.
The individuals or cells as a result of mitosis are haplonts, hence this life cycle is also called haplontic life cycle. Haplonts are:7
- Most fungi
- Some green algae
- Many protozoa

# Diplontic life cycle
In gametic meiosis, instead of immediately dividing meiotically to produce haploid cells, the zygote divides mitotically to produce a multicellular diploid individual or a group of more unicellular diploid cells.  Cells from the diploid individuals then undergo meiosis to produce haploid cells or gametes. Haploid cells may divide to form more haploid cells, as in many yeasts, but the haploid phase is not the predominant life cycle phase.  In most diplonts, mitosis occurs only in the diploid phase, i.e. gametes usually form quickly and fuse to produce diploid zygotes.
In the whole cycle, gametes are usually the only haploid cells, and mitosis usually occurs only in the diploid phase.
The diploid multicellular individual is a diplont, hence a gametic meiosis is also called a diplontic life cycle. Diplonts are:
- Animals
- Some brown algae
- Some fungi, e.g. brewer's yeast

# Life history
The term "Life history" is better than "life cycle" especially for the red algae (Rhodophyta). In the Rhodophyceae there are generally three stages and thus "alternation of generations" is not suitable.

# Life history theory
In animal and human biology life history theory is a method of understanding evolved behaviors and strategies to optimize reproductive success.
Blocking (statistics)

# Overview
In the  statistical theory of the design of experiments, blocking is the arranging of experimental units in groups (blocks) that are similar to one another. For example, an experiment is designed to test a new drug on patients. There are two levels of the treatment, drug, and placebo, administered to male and female patients in a double blind trial. The sex of the patient is a blocking factor accounting for treatment variability between males and females.  This reduces sources of variability and thus leads to greater precision.
Suppose we have invented a process which we believe makes the soles of shoes last longer, and we wish to conduct a field trial. One possible design would be to have a group of n volunteers, give 0.5n of them shoes with the new soles and .5n of them regular shoes, randomizing (see randomization) the assignment of the two types of shoes. This type of experiment is a completely randomized design.
We can then let both groups use their shoes for a suitable period of time and then compare them. A better design would be to give each person one regular sole and one new sole where random assignment of the two treatments to the left or right shoe of each volunteer is conducted. Such a design is called a randomized complete block design. This design will be more sensitive than the first, because each person is acting as their own control and thus the control group is more closely matched to the treatment group. The theoretical basis of blocking is the following mathematical result. Given random variables, X and Y
\operatorname{var}(X-Y)= \operatorname{var}(X) + \operatorname{var}(Y) - 2\operatorname{cov}(X,Y).
The difference between the treatment and the control can thus be given minimum variance (i.e. maximum precision) by maximising the covariance (or the correlation) between X and Y.
Blood-retinal barrier
The blood-retinal barrier, or the BRB, is part of the blood-ocular barrier that consists of cells that are joined tightly together in order to prevent certain substances from entering the tissue of the retina. It consists of non-fenestrated capillaries of the retinal circulation and tight-junctions between retinal epithelial cells preventing passage of large molecules from choriocapillaris into the retina. The blood retinal barrier has two components: the retinal vascular endothelium and the retinal pigment epithelium. Retinal blood vessels that are similar to cerebral blood vessels maintain the inner blood-ocular barrier. This physiological barrier comprises a single layer of non-fenestrated endothelial cells, which have tight junctions. These junctions are impervious to tracer, so many substances can impact the metabolism of the eyeball. The retinal pigment epithelium maintains the outer blood-retinal barrier.
Diabetic retinopathy, eye damage that frequently occurs as a result of diabetes, is related to the breakdown of the blood-retinal barrier. The barrier becomes more leaky in patients with diabetic retinopathy.
Animal models have shown that the blood-retinal barrier becomes more permeable to substances in hypertensive animals (those with high blood pressure).
Bone marrow disorders
For congenital bone marrow disorders, click here.
For acquired bone marrow disorders, click here.

# Overview
Bone marrow disorders are classified into congenital bone marrow disorders and acquired bone marrow disorders.

# Definition of Terms
- Bone marrow suppression: Reduced numbers of cells in the bone marrow
Myelosuppression: Reduced number of myeloid lineage cells (RBC, neutrophils, basophils, eosinophils, monocytes, platelets, mastocytes)
Immunosuppression or lymphosuppression: Reduced number of lymphoid lineage cells (T-cell, B-cell, NK cell)
- Myelosuppression: Reduced number of myeloid lineage cells (RBC, neutrophils, basophils, eosinophils, monocytes, platelets, mastocytes)
- Immunosuppression or lymphosuppression: Reduced number of lymphoid lineage cells (T-cell, B-cell, NK cell)
- Bone marrow proliferation: Increased numbers of cells in the bone marrow
Myeloproliferation: Increased number of myeloid lineage cells (RBC, neutrophils, basophils, eosinophils, monocytes, platelets, mastocytes)
Immunoproliferation or lymphoproliferation: Increased number of lymphoid lineage cells (T-cell, B-cell, NK cell)
- Myeloproliferation: Increased number of myeloid lineage cells (RBC, neutrophils, basophils, eosinophils, monocytes, platelets, mastocytes)
- Immunoproliferation or lymphoproliferation: Increased number of lymphoid lineage cells (T-cell, B-cell, NK cell)

# Classification
Shown below is an algorithm depicting the different classes of bone marrow disorders.
Bootstrap aggregating

# Overview
Bootstrap aggregating (bagging) is a meta-algorithm to improve classification and regression models in terms of stability and classification accuracy. Bagging also reduces variance and helps to avoid overfitting. Although this method is usually applied to decision tree models, it can be used with any type of model. Bagging is a special case of the model averaging approach.
Given a standard training set D of size N, we generate L new training sets D_i also of size N' (N' < N) by sampling examples uniformly from D, and with replacement. By sampling with replacement it is likely that some examples will be repeated in 
each D_i. If N'=N, then for large N the set D_i expected to have 63.2% of the examples of D, the rest being duplicates. This kind of sample is known as a bootstrap sample. The L models are fitted using the above L bootstrap samples and combined by averaging the output (in case of regression) or voting (in case of classification). One particular interesting point about bagging is that, since the method averages several predictors, it is not useful to improve linear models.

# Example: Ozone data
This example is rather artificial, but is intended to illustrate the principles.
Rousseeuw and Leroy (1986) describe a data set concerning ozone levels. The data are available via the classic data sets page. All computations were performed in  R.
A scatter plot reveals an apparently non-linear relationship between temperature and ozone. One way to model the relationship is to use a loess smoother. Such a smoother requires that a span parameter be chosen. In this example, a span of 0.5 was used.
One hundred  bootstrap samples of the data were taken, and the LOESS smoother was fit to each sample. Predictions from these 100 smoothers were then made across the range of the data. The first 10 predicted smooth fits appear as grey lines in the figure below. The lines are clearly very wiggly and they overfit the data - a result of the span being too low.
The red line on the plot below represents the mean of the 100 smoothers. Clearly, the mean is more stable and there is less overfit. This is the bagged predictor.
File:Ozone.png

# History
Bagging (Bootstrap aggregating) was proposed by Leo Breiman in 1994 to improve the classification by combining classifications of randomly generated training sets. See Breiman, 1994. Technical Report No. 421.
Boutonniere deformity

# Overview
Boutonniere deformity refers to a finger which is bent in a particular way:  bent toward the palm at joint nearest the knuckles, and bent back away from the palm at the joint furthest from the knuckles (hyperflexion at the proximal interphalangeal joint with hyperextension at the distal interphalangeal joint.
Causes are injury, inflammatory conditions like rheumatoid arthritis.

# Stages
- Mild extension lag, passively correctable
- Moderate extension lag, passively correctable
- Mild flexion contracture
- Advanced flexion contracture
Higher numbers indicate a more severe problem and greater likelihood of a poor final outcome

# Pathophysiology
This is a flexion deformity of the proximal interphalangeal joint, due to interruption of the central slip of the extensor tendon.  This makes it difficult or impossible to extend the proximal interphalangeal joint.  The lateral slips separate and the head of the proximal phalanx pops through the gap like a finger through a button hole and the distal joint is drawn into hyperextension.  It is often seen with trauma or rheumatoid arthritis.
Bovine virus diarrhea
Bovine Virus Diarrhea (BVD) is a disease of cattle which reduces productivity and increases death loss. It is caused by a Pestivirus from the family Flaviviridae. Classical swine fever (CSF) is also caused by a pestivirus. CSF and BVD are notifiable diseases and eradication programms are administered in many countries worldwide. The molecular biology of pestiviruses shares many similarities and peculiarities with the human hepaciviruses. Pestiviruses have the ability to establish persistent infection during pregnancy. Persistent infection with pestiviruses often goes unnoticed; for BVDV frequently nonhomologous RNA recombination events lead to the appearance of genetically distinct viruses that are lethal to the host.
Clinical signs of mucosal erosions and diarrhea which occur in the acute form of BVD have a significant effect on those animals infected, but much more costly are those animals who are persistently infected animals or PI's.
Typically, PI's fail to reach their genetic potential, exhibiting decreased weight gain, increased disease susceptibility, and reduced fertility. They shed the virus, causing reproductive loss in the unimmunized animals in the herd. The most important components in programs that reduce or eliminate BVD are vaccinations, testing, and biosecurity. MLV(modified-live) vaccinations are one of the more important means of providing superior immunity to BVD, to protect against exposure to the virus, from both acutely infected individuals and PI animals.
PI's result from cows being exposed to the virus between 45 & 125 days of gestation in which case the fetus fails to recognize the virus as a foreign invader, allowing it to become 'self', and letting the infection persist after birth. The resulting calves shed the virus, often in great numbers, such that even well-vaccinated animals may become infected. PI individuals often do not exhibit any symptoms of disease but are very damaging to a herd.  Since the virus is present in the persistently infected animals at birth and throughout their life, and an animal may only become PI prior to birth, an animal only has to be tested once at any age to establish its PI status. Normal serological tests do not work since the PI does not produce a normal immune response.  Serum, milk, or a skin biopsy (ear punch) can be tested with polymerase chain reaction or Ag Capture Elisa (ACE).
Breakthrough bleeding
Breakthrough bleeding is bleeding while taking the active pills of combined oral contraceptives, or other hormonal contraceptives. The bleeding is usually light, often referred to as "spotting," though a few women may experience heavier bleeding. Breakthrough bleeding is most common when a woman first begins taking oral contraceptives, or changes from one particular oral contraceptive to another, though it is possible for breakthrough bleeding to happen at any time. Smokers are especially prone to breakthrough bleeding while taking oral contraceptives; though many users experience breathrough bleeding in the first three cycles of taking the pill, non-smokers tend to see the bleeding dissipate more quickly than smokers.
Many women find that the breakthrough bleeding ceases after one or two cycles. Breakthrough bleeding that does not resolve on its own is a common reason for women to switch to different pill formulations, or to switch to a non-hormonal method of birth control.
Breakthrough bleeding is most commonly caused by an excessively thick endometrium (uterine lining). This is not a dangerous condition, though the unpredictable and often lengthy periods of bleeding are unpleasant for the woman. Breakthrough bleeding may also be caused by hormonal effects of ovulation. If the pill is not suppressing ovulation, the woman is at high risk of pregnancy. Breakthrough bleeding may also itself be a symptom of pregnancy (contraceptive failure).
Somatization disorder
Synonyms and keywords: Briquet's disorder

# Overview
Somatization disorder  is a psychiatric diagnosis applied to patients who chronically and persistently complain of varied physical symptoms that have no identifiable physical origin. One common general etiological explanation is that internal psychological conflicts are unconsciously expressed as physical signs.

# Pathophysiology
There is usually co-morbidity with other psychological disorders, particularly mood or anxiety disorders.

# Epidemiology and Demographics

## Prevalence
Somatization disorder is not common in the general population.

## Gender
It is thought to occur in 0.2% to 2% of females, and, according to the DSM-IV, 0.2% of males.

# Natural History, Complications and Prognosis
This condition is chronic and has a poor prognosis.

# Diagnosis

## History and Symptoms

### Criteria
Somatization disorder is  a somatoform disorder. The DSM-IV establishes the following five criteria for the diagnosis of this disorder:
- A history of somatic symptoms prior to the age of 30
- Pain in at least four different sites on the body
- Two gastrointestinal problems other than pain such as vomiting or diarrhea
- One sexual symptom such as lack of interest or erectile dysfunction
- One pseudoneurological symptom similar to those seen in Conversion disorder such as fainting or    blindness.
Such symptoms cannot be related to any medical condition. The symptoms do not all have to be occurring at the same time, but may occur over the course of the disorder. If a medical condition is present, then the symptoms must be excessive enough to warrant a separate diagnosis. Two symptoms can not be counted for the same thing e.g.if pain during intercourse is counted as a sexual symptom it can not be counted as a pain symptom. Finally, the symptoms cannot be being feigned out of an effort to gain attention or anything else by being sick, and they can not be deliberately induced symptoms.

# Treatment
No one treatment has been found to cure somatization disorder. However, setting up a physician that screens complaints from patients before they are allowed to see a specialist significantly cuts down on cost of the disorder. Antidepressants and cognitive behavioral therapy have been shown to help treat the disorder.
Collaboration between a psychiatrist and primary care physician may help.

# Related Chapters
- Culture-bound syndrome
- Psychosomatic illness