New Potential Class of Long Gamma-Ray Bursts

New Potential Class of Long Gamma-Ray Bursts Intro Since their discovery, a debate has been sparked over the classification of a new potential class of long gamma-ray bursts (LGRB) that possess ultra-long durations lasting at least 1000s, along with distinctly different x-ray and optical light curves to regular gamma-ray bursts (GRB) (Levan 2014). The search for members of the ultra-long gamma-ray burst (ULGRB) population is currently gaining traction, with some suggesting they may be commonly occurring despite difficulties detecting them (levan 2014) and that their origins may be uniquely different from regular LGRBs (Boer 2015). It is thought that ULGRBs are produced by stars of very large radii evolving into an engine driven super-luminous supernova (SLSN), rather than an envelope stripped compact Wolf-Rayet star which is commonly accepted as a progenitor for LGRBs (levan 2014), however, the connection between SN signatures and ULGRBs is an ambiguous one. More recent work has been centred on exploring this partially vague connection, attempting to refine models explaining an engine driven SLSN, the nature of their progenitors and the host galaxy properties (bersten, kann, japlj, gao). The focus of this work is on two papers in this area of astrophysics: A very luminous magnetar-powered supernova associated with an ultra-long gamma-ray burst, (Greiner) and The Diversity of Transients from Magnetar Birth, (Metzger). The former details the discovery and observational analysis of SN2011k, preceded by GRB111209A, and postulates a magnetar origin, whereas the latter acknowledges the ULGB-SLSN connection and builds a thorough model of magnetar formation in order to explain it. A very luminous magnetar-powered supernova associated with an ultra-long gamma-ray burst Summary The work performed by (greiner) at first focuses on observational data of GRB111209A taken with GROND, a 7-channel imager specifically designed for rapid observations of GRB afterglows that performs simultaneous imaging in the Sloan grIz and near infra-red JHK bands. Use of the GROND imager gives the authors the ability to calculate multiple properties of the GRB, such as photometric redshift, the intrinsic power law slope of the continuum emission, and the galactic host emission, which can all be done in a short window and   monitored as the GRB afterglow evolves (greiner 2008). z΄ GROND was used on 16 epochs with logarithmic temporal spacing until 72 days after the GRB was detected by the Swift satellite on December 9 2011; however, readings were interrupted by the Sun until 280 days after detection when a final epoch for host photometry was obtained. There is also inclusion of supplementary observations of the GRB afterglow: u-band observations from Swift with applied UVOT photometry; HST F336W/F125W data from 11.1 and 35.1 days after the GRB, respectively; two epochs of VLT(X-shooter)/FORS2 g΄RCi΄z΄ data during the SN phase; a late-time Gemini-S u΄-band observation 198 days after the GRB. Data tables for all GROND and Swift data can be found in Appendix A. GRB111209A was measured to last ~10,000s at a redshift of z=0.677, and to have an equivalent isotropic energy output of Eiso = (5.7à ¯Ã¢â‚¬Å¡Ã‚ ±0.7)à ¯Ã¢â‚¬Å¡Ã‚ ´1053 erg which is among the brightest of LGRBs. After analysis of the VLT/X-shooter spectrum, obtained near the peak of excess emission and detailed below, (greiner) deduces this emission to be caused by a SN, dubbed SN2011k1, because of similarities in spectral shape to known GRB-SNe and development in time and colour. Decomposition of the GRB afterglow is shown in figure 1 which displays data from GROND and other instruments. Since the authors accurately determined the host galaxy emission, they were able to subtract it from the GRB afterglow. The optical light curve displays a deviation from its initial power law decay, remaining flat for around 15 days, before decaying again. They also plot the light curve in the u-band showing a steeper decay slope >10 days where the initial slope is a1.. and the second a2 Since there is no contribution from the associated SN in the u-band, they explain that they can build a template for the pure afterglow contribution from the SN. The authors construct a quasi-bolometric light curve for the SN from GROND and supplementary data by first extinction-correcting filter band with Avà ¢Ã¢â€š ¬Ã‚ ¦, galactic foreground, and Avhostà ¢Ã¢â€š ¬Ã‚ ¦ which was derived from the GRB afterglow spectral energy distribution, then secondly deriving quadratic polynomials for sets of 3 consecutive filters, which were combined to form the light curve.   They then integrate the polynomials over rest-frame wavelength from 3860/(1+z) Ã… to 13560/(1+z) Ã…, corresponding to the blue limit of the g-band filter to the red limit of the J filter, and used k-correction computed from the spectral energy distribution. Finally, they transformed the integrated flux into luminosity (figure 2), employing a luminosity distance of d=4080 Mpc, using concordance cosmology (à ¯Ã‚ -à ¯Ã‚ Ã…’=0.73, à ¯Ã‚ -m=0.27, and H0=71 km sà ¯Ã¢â€š ¬Ã‚ ­1 Mpcà ¯Ã¢â€š ¬Ã‚ ­1) Using data from the VLT/X-shooter spectrum, which is the sum of light from the GRB afterglow, the GRB host galaxy, and the supernova SN 2011kl and taken near the SN peak, (greiner) again subtracts the GRB and host contributions followed by rest-frame conversion and correction for intrinsic reddening of E(Bà ¯Ã¢â€š ¬Ã‚ ­V)=0.04à ¯Ã¢â‚¬Å¡Ã‚ ±0.01 mag. They use this data, shown in figure 3, to draw similarities between SN2011k1 and SLSN, noting that its flat shape and high UV flux is clearly different from the brightest known GRB-SNe. When comparing this spectrum (figure 3) to the GRB afterglow, they find that there is no change in absorption lines or redshift and that they are similar to those found in hosts of LGRBs, thus relating SN2011k1 to the same galaxy as GRB111209A. Also mentioned in this comparison is that there is no offset between the GRB afterglow and SN images, which the authors say implies the events are co-spatial to within Spectral analysis of SN2011k1 reveals very low metal content and lack of H or He, unlike typical SNe Ic associated with LGRBs, therefore, (greiner) apply parameterized SN light curve fits to derive an ejecta mass Mej = 3à ¯Ã¢â‚¬Å¡Ã‚ ±1 Mà ¢Ã…  Ã¢â€ž ¢ and a 56Ni mass of 1.0à ¯Ã¢â‚¬Å¡Ã‚ ±0.1 Mà ¢Ã…  Ã¢â€ž ¢ for photospheric velocity vph = 20,000 km/s, and a grey opacity of 0.07à ¯Ã¢â‚¬Å¡Ã‚ ±0.01 cm2 gà ¯Ã¢â€š ¬Ã‚ ­1. The high Ni/Mej ratio is reported to be incompatible with the spectrum (figure 3) and thus the authors seek an alternative explanation for the luminosity source. The likeness of SN2011k1 to SLSNe, its host galaxy properties, low metal abundance, improbable Ni powered luminosity and association with GRB111209A lead to the authors to suggest a magnetar origin for this event, stating that post-birth from the collapse of a massive star it powers the surrounding ejecta for a super-luminous effect. This hypothesis is evidenced by reproducing the SN spectrum via sampling of   magnetar initial spin period Pi, magnetic dipole field strength B, Mej and rotational energy Ek. Best fits to the data found P=12.2à ¯Ã¢â‚¬Å¡Ã‚ ±0.3 ms and B=7.5à ¯Ã¢â‚¬Å¡Ã‚ ±1.5à ¯Ã¢â‚¬Å¡Ã‚ ´1014 G for observed short tpeak (à ¯Ã‚ Ã‚ ¾14 rest-frame days) and moderate peak luminosity, as well as Mej=2.4 ±0.7 Mà ¢Ã…  Ã¢â€ž ¢ and energy EK=(5.5à ¯Ã¢â‚¬Å¡Ã‚ ±3.3)à ¯Ã¢â‚¬Å¡Ã‚ ´1051 erg. Importance and Implications The significance of this paper arises from its robust analysis of the GRB111209A afterglow and SN2011k1 using multiple datasets on top of their own data, collected with GROND. It is clear that the development (g2008) and implementation of this instrument is extraordinarily useful in this area of observational astrophysics due to its multiple measurement taking capabilities. Without this device, it is unlikely the authors could have developed their results as well as they have done, despite much of their comparison data coming from other sources, such as the ESO VLT/X-shooter. On the note of observational data analysis, there are a few important points to consider underneath the various statistical methods and rebinning mentioned in this paper. It is explained that the SN light curve error depends on the decay slope a2 remaining constant after the last afterglow measurement before onset of the SN, and since the GRB light curve is observed to steepen, the authors claim their SN luminosity measurement of 2.8+1.2-1.0 x 1043 erg/s is in fact a lower limit. They also explain that they lack any near-infrared measurements for SN2011k1, acknowledging that the bolometric peak luminosity could be underestimated by 5%-30%. A crucial achievement from this paper is that a SN with such high bolometric peak luminosity was detected, not only within the same host galaxy, but to within Evidently the authors are confident that neither the GRB is caused by a tidal disruption event, or that the unusual SN spectrum and luminosity is caused by 56Ni brightening and hence distancing it from SNIc. The former is explained by the lack of ejecta and fall back accretion time being too short to produce an ULGRB, and the latter simply by the overly large amount of 56Ni needed to reproduce the spectrum of SN2011k1. Formation and subsequent accretion of matter on a black hole is also rejected, leaving the authors to suggest the birth of a magnetar as the cause, and as seen in fig 2 their model reproduces the quasi-bolometric spectrum of SN2011k1 rather well without invoking any 56Ni interaction. Critical Assessment This paper is difficult to follow for a number of reasons. The layout is most unusual for a scientific report; it presents the abstract, which is well written and informative, then without a section heading proceeds to give a few paragraphs summarising their observational findings, with some values then absent in crucial places throughout the remainder of the work. These paragraphs are followed by a qualitative description of their interpretations for an origin of GRB111209A and SN2011k1 and their modelling of magnetar SN enhancement, in attempt to draw connections. At the end of this section, they suggest that the events could have been caused by formation of a magnetar which then lives on to power SN2011k1, and up to this point they make a good argument. The problem with this argument is that it is devoid of any mathematical content, and all the data provided is in the three graphs included in this work or essentially contained in references to other papers, making it difficult to decipher which parts (greiner) did themselves, or how they did it. The captions for each figure are also all on separate pages to the figures, located after the end of the untitled section and a collection of references. Beyond this point is a Methods section with seven 7 subsections, each with their own title and even some supplementary data to explain the origin of their work. Unfortunately, this part of the paper feels cyclical and can often feel at odds with methods they had already discussed. For example, they talk about subtracting the host galaxy emission from most of the light curves, but at multiple points in between mention they firstly have to build a template for the emission, which is detailed in a later section to be constructed from GROND data and using LePHARE . Again, there is a complete lack of mathematical clarity on their methods, however, it appears that the majority is all computational statistics performed on their copious data sources or modelling techniques. Even when discussing the origin for their magnetar properties, they give a simple qualitative explanation which should probably have been accompanied by some mathematics. When all of this is put together, it makes for an excruciatingly difficult read. There are inconsistencies everywhere in its presentation and in some comments of the work, making one wonder why they would read it again. Despite (greiner) providing some outstanding results and performing brilliant analysis on the afterglow of GRB2011k1 and spectrum of SN2011k1, the details of their work is lost to disorganisation. The Diversity of Transients from Magnetar Birth Summary This paper takes an approach to modelling physical properties of highly magnetized, millisecond rotational neutron stars, known as magnetars, in order to unify ULGRBs and SLSNe in a common framework. The authors intend to show that under their model, both of these events can be explained individually with a magnetar central engine and simultaneously via magnetar formation, as well as stating that the transition from ULGRBs to SLSNe is a natural consequence of the model. They focus on the observations of GRB111209A and SN2011k1 as a benchmark since the pair were found to be closely associated events, whilst also including various observational signatures of magnetar formation. Also discussed is the SLSN, ASASSN-15lh, which has the highest recorded peak luminosity of à ¢Ã¢â€š ¬Ã‚ ¦ (very recently it has been suggested to be a tidal disruption event (leloudas)). This event challenges the magnetar central engine model because of its extreme energy peaks, however, the authors go on to sh ow that the maximum energy output from magnetars was previously underestimated and hence fit ASASSN-15lh within their model. The proto-magnetar spin-down energetics used in the model were given as follows: firstly, the rotational energy of a magnetar with mass is where is the NS moment of inertia and is the rotational period. The rate which the NS loses rotational energy for an aligned force-free wind is given by is the spin-down luminosity, the NS magnetic dipole moment and is the surface equatorial dipole field, with a radius 12 km and is the initial spin-down time. The authors note that, although the correction is minor for ULGRBs, the spin-down luminosity given in equation eqref{2} is exceeded for a few seconds after core bounce due to neutrino-heated wind. (Metzger) secondly consider the constraints on the GRB jet collimation and how the NS properties described by the above equations can be translated to derive opening angle conditions for observed peak luminosity. Though a stable jet may be formed, it may not cleanly escape the star over time, tsd, of peak spin-down power. This is because there is uncertainty over whether the strong toroidal magnetic field in the nebula, separating the magnetar wind from the surrounding star, remains stable in the case of non-asymmetric instabilities. It is required, for a jet of luminosity Lj and half opening angle à ¢Ã¢â€š ¬Ã‚ ¦, that tesc Where (Metzger) assume Erot=à ¢Ã¢â€š ¬Ã‚ ¦ since the kinetic energy of the explosion is dominated by the magnetar rotational energy. A cleanly escaping jet will then have a peak spin-down luminosity of Lj=.., implying that the observed isotropic gamma-ray luminosity is Liso=.., where e= is the radiative efficiency and fb=.. the beaming fraction. The authors state that, assuming the propagation time through the star is negligible, we can expect the GRB duration, Ty, to be such that Ty=.. Lastly, the authors describe how SN mass ejecta, Mej, thermalizes over time through adiabatic expansion and 56Ni decay (the standard process for type Ic SNe), which is enhanced by input from the NS to super-luminous levels. The thermal energy E evolution over time t as the ejecta expands is given by For an initial kinetic energy of Eokà ¢Ã¢â€š ¬Ã‚ ¦ , where the LHS accounts for PdV losses, vej=.. is the ejecta velocity and rej the mean radius. Conservation of energy requires that the kinetic energy Ek=à ¢Ã¢â€š ¬Ã‚ ¦ increases due to the work done from PdV, thus dEk=à ¢Ã¢â€š ¬Ã‚ ¦ Lsn=à ¢Ã¢â€š ¬Ã‚ ¦ is the radiated luminosity, where td=.. is the photon diffusion timescale, with k=à ¢Ã¢â€š ¬Ã‚ ¦ the optical opacity which is set by electron scattering and Doppler broadening lines. Lni=à ¢Ã¢â€š ¬Ã‚ ¦ is the rate of heating due to 56Ni decay where Mni is the 56Ni mass. The final term is the energy input from the magnetar which is assumed to thermalize the ejecta with unity efficiency.

The Presentation of Self in Everyday

In his book, The Presentation of Self in Everyday Life, Erving Goffman compares life to acting. He argues that â€Å"when the individual is in the immediate presence of others, his activity will have a promissory character† (Goffman 2). I think it is ironic because I always thought that movies or theaters have always tried to imitate reality and not the other way around. In order to clearly show his analogy, Goffman presents elements of acting such as the front. We are all familiar with the term front act.† In Goffman’s opinion, people are all playing an act. This is such a bold claim to make because he is saying that we are all just performing and not being our real selves, though there are some truths to his claim. What is confusing is when do we really act, or when do we be ourselves? Most of us would not acknowledge his belief that we are playing a character, but then again, the person that denies this may also just be playing a role, and so the question remai ns unanswered.One idea of Goffman that caught my attention is his theory that people cooperate in an act to cover, say, something embarrassing. I have experienced it myself—I would pretend that I have not witnessed someone undergo an embarrassing moment, although unconsciously, I was not trying to make that person feel the embarrassment more, but rather, I was just trying not to be mean.It did not occur to me that by pretending (and therefore joining in the scene, or rather excluding myself from the scene) not to see the embarrassing act, I have helped in saving that person’s face. What follows is an array of lectures, as it were, like that of a professor teaching a theater or film student, only that his lectures are philosophical and are related to our everyday lives. After reading Goffman’s work, I found myself smiling because of the truths in his analogies that never crossed my mind before.

Example Of The Medicaid Benefits - 1046 Words

They are expected to pay a portion of their health care costs. Keep in mind though that these are elderly and disabled citizens, usually on fixed and very limited incomes. These Medicare members will always more than qualify for Medicaid benefits. The Medicaid program differs by state. There are dozens of ways to qualify for this state and federally funded health insurance program. There are Medicaid programs for the low-income, disabled, elderly, children, and long-term care. â€Å"Since its inception in 1965, the Medicaid program has evolved to become the largest single source of health coverage in the United States† (Crowley Golden, 2014). From its beginnings the goal of single payer health care is on a slow roll for all citizens. Some†¦show more content†¦Private Insurance Private insurance is a way to help mitigate the rising cost of health care in the US. Health care and health insurance get used interchangeably in the US but they are vastly different. Pri vate insurance is generally paid by a combination of employer and employee contributions. This helps reduce the impact of the cost of health care for those who have it. The analogy that researchers use is that the stereotype is that a privately held hospital will assist you much better because they have the money to do so. A nonprofit hospital will be less beneficial in treating patients because they lack the equipment and staff to do so. This article argues that nonprofit organizations can be inferior to for profit, even if markets are incomplete. This is beneficial to the paper because it will show the structure financially what privately and non- profit hospitals must offer (Kessler, McClellan, 2002). The profit that private insurance creates supports the economy and continues to help invocation in treatments. However private insurance does not cover all of the cost of health care. 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Famous Female Chemists and Chemical Engineers

Women have made many important contributions to the fields of chemistry and chemical engineering. Heres a list of female scientists and a summary of the research or inventions that made them famous. Jacqueline Barton - (USA, born 1952) Jacqueline Barton probes DNA with electrons. She uses custom-made molecules to locate genes and study their arrangement. She has shown that some damaged DNA molecules do not conduct electricity. Ruth Benerito - (USA, born 1916) Ruth Benerito invented wash-and-wear cotton fabric. Chemical treatment of the cotton surface not only reduced wrinkles, but could be used to make it flame resistant and stain resistant. Ruth Erica Benesch - (1925-2000) Ruth Benesch and her husband Reinhold made a discovery that helped explain how hemoglobin releases oxygen in the body. They learned that carbon dioxide functions as an indicator molecule, causing hemoglobin to release oxygen where carbon dioxide concentrations are high. Joan Berkowitz - (USA, born 1931) Joan Berkowitz is a chemist and environmental consultant. She uses her command of chemistry to help solve problems with pollution and industrial waste. Carolyn Bertozzi - (USA, born 1966) Carolyn Bertozzi has helped design artificial bones that are less likely to cause reactions or lead to rejection than their predecessors. She has helped create contact lenses that are better-tolerated by the cornea of the eye. Hazel Bishop - (USA, 1906–1998) Hazel Bishop is the inventor of smear-proof lipstick. In 1971, Hazel Bishop became the first female member of the Chemists’ Club in New York. Corale Brierley Stephanie Burns Mary Letitia Caldwell Emma Perry Carr - (USA, 1880–1972) Emma Carr helped to make Mount Holyoke, a womens college, into a chemistry research center. She offered undergraduate students the opportunity to conduct their own original resarch. Uma Chowdhry Pamela Clark Mildred Cohn Gerty Theresa Cori Shirley O. Corriher Erika Cremer Marie Curie - Marie Curie pioneered radioactivity research. She was the first two-time Nobel laureate and the only person to win the award in two different sciences (Linus Pauling won Chemistry and Peace). She was the first woman to win a Nobel Prize. Marie Curie was the first female professor at the Sorbonne. Irà ©ne Joliot-Curie - Irà ©ne Joliot-Curie was awarded the 1935 Nobel Prize in Chemistry for synthesis of new radioactive elements. The prize was shared jointly with her husband Jean Frà ©dà ©ric Joliot. Marie Daly - (USA, 1921–2003) In 1947, Marie Daly became the first African American woman to earn a Ph.D. in chemistry. The majority of her career was spent as a college professor. In addition to her research, she developed programs to attract and aid minority students in medical and graduate school. Kathryn Hach Darrow Cecile Hoover Edwards Gertrude Belle Elion Gladys L. A. Emerson Mary Fieser Edith Flanigen - (USA, born 1929) In the 1960s, Edith Flanigen invented a process for making synthetic emeralds. In addition to their use for making beautiful jewelry, the perfect emeralds made it possible to make powerful microwave lasers. In 1992, Flanigen received the first Perkin Medal ever awarded to a woman, for her work synthesizing zeolites. Linda K. Ford Rosalind Franklin - (Great Britain, 1920–1958) Rosalind Franklin used x-ray crystallography to see the structure of DNA. Watson and Crick used her data to propose the double-stranded helical structure of the DNA molecule. The Nobel Prize could only be awarded to living persons, so she could not be included when Watson and Crick were formally recognized with the 1962 Nobel Prize in medicine or physiology. She also used x-ray crystallography to study the structure of the tobacco mosaic virus. Helen M. Free Dianne D. Gates-Anderson Mary Lowe Good Barbara Grant Alice Hamilton - (USA, 1869–1970) Alice Hamilton was a chemist and physician who directed the first governmental commission to investigate industrial hazards in the workplace, such as exposure to dangerous chemicals. Because of her work, laws were passed to protect employees from occupational hazards. In 1919 she became the first female faculty member of Harvard Medical School. Anna Harrison Gladys Hobby Dorothy Crowfoot Hodgkin - Dorothy Crowfoot-Hodgkin (Great Britain) was awarded the 1964 Nobel Prize in Chemistry for using x-rays to determine the structure of biologically important molecules. Darleane Hoffman M. Katharine Holloway - (USA, born 1957) M. Katharine Holloway and Chen Zhao are two of the chemists who developed protease inhibitors to inactivate the HIV virus, greatly extending the lives of AIDS patients. Linda L. Huff Allene Rosalind Jeanes Mae Jemison - (USA, born 1956) Mae Jemison is a retired medical doctor and American astronaut. In 1992, she became the first black woman in space. She holds a degree in chemical engineering from Stanford and a degree in medicine from Cornell. She remains very active in science and technology. Fran Keeth Laura Kiessling Reatha Clark King Judith Klinman Stephanie Kwolek Marie-Anne Lavoisier - (France, circa 1780) Lavoisiers wife was his colleague. She translated documents from English for him and prepared sketches and engravings of laboratory instruments. She hosted parties at which prominent scientists could discuss chemistry and other scientific ideas. Rachel Lloyd Shannon Lucid - (USA, born 1943) Shannon Lucid as an American biochemist and US astronaut. For a while, she held the American record for the most time in space. She studies the effects of space on human health, often using her own body as a test subject. Mary Lyon - (USA, 1797–1849) Mary Lyon founded Mount Holyoke College in Massachusetts, one of the first womens colleges. At the time, most colleges taught chemistry as a lecture-only class. Lyon made lab exercises and experiments an integral part of undergraduate chemistry education. Her method became popular. Most modern chemistry classes include a lab component. Lena Qiying Ma Jane Marcet Lise Meitner  - Lise Meitner (November 17, 1878 – October 27, 1968) was an Austrian/Swedish physicist who studied radioactivity and nuclear physics. She was part of the team that discovered nuclear fission, for which Otto Hahn received a Nobel Prize. Maud Menten Marie Meurdrac Helen Vaughn Michel Amalie Emmy Noether  - (born in Germany, 1882-1935) Emmy Noether was a mathematician, not a chemist, but her mathematical description of the conservation laws for energy, angular momentum, and linear momentum has been invaluable in spectroscopy and other branches of chemistry. She is responsible for Noethers theorem in theoretical physics, the Lasker–Noether theorem in commutative algebra, the concept of Noetherian rings, and was co-founder of the theory of central simple algebras. Ida Tacke Noddack Mary Engle Pennington Elsa Reichmanis Ellen Swallow Richards Jane S. Richardson  - (USA, born 1941) Jane Richardson, a biochemistry professor at Duke University, is best-known for her hand-drawn and computer-generated portaits of proteins. The graphics help scientists understand how proteins are made and how they function. Janet Rideout Margaret Hutchinson Rousseau Florence Seibert Melissa Sherman Maxine Singer  - (USA, born 1931) Maxine Singer specializes in recombinant DNA technology. She studies how disease-causing genes jump within DNA. She helped formulate the NIHs ethical guidelines for genetic engineering. Barbara Sitzman Susan Solomon Kathleen Taylor Susan S. Taylor Martha Jane Bergin Thomas Margaret E. M. Tolbert Rosalyn Yalow Chen Zhao  - (born 1956) M. Katharine Holloway and Chen Zhao are two of the chemists who developed protease inhibitors to inactivate the HIV virus, greatly extending the lives of AIDS patients.