Analysis of Solutions for Surface Active Agents

The objective of this study was to obtain a better understanding of the behavior of surfactants in aqueous solutions at electrodes. With this understanding it should be possible to design electrochemical methods for the detection, identification, and quantitative determination of such substances. This study was concerned primarily with the influence of extraneous salts on the behavior of surface active agents when these are examined by the electrochemical technique known as tensammetry. The tensammetric method consists essentially of the measurement of the electrical impedance of an electrochemical cell. This impedance is characteristically increased in the presence of surfactants at those potentials where the surfactants are absorbed on the electrode. At sufficiently negative and at sufficiently positive polarization, surfactants are absorbed, and at these absorption potentials, the impedance of the cell is decreased. Curves of admittance as a function of polarization of the electrode therefore usually sh.ow two tensammetric waves. The extent of surface activity is proportional to the separation between the two tensammetric waves, to the heights of these waves, and to the degree to which the impedance is increased at polarizations between the two waves. Since tensammetric measurements can be made only in solutions of sufficiently high conductivity, the nature and effects of added salts on the result obtained is a considerable importance. In this study it was found that the salt effect is relatively unimportant when the salt concentration is not greater than approximately 0.1 m. This concentration might then be used as a standard condition for making measurements of the surfactant concentration in aqueous solution. The applicability of the technique to the analysis of surface active agents under actual field conditions was not attempted

The polarographic reduction of Bi(III) in the presence of chloride ion

The reduction of Bi(III) to Bi(Hg) at the dropping mercury electrode in 0[middle dot]5 M perchloric acid solution containing 0-0[middle dot]3 M chloride ion becomes increasingly reversible, generally speaking, as the [Cl-]/ [Bi(III)] ratio increases, as evidenced by changes in various criteria used for determining the "reversibility" of a polarographic electrode process, e.g., the magnitude of the heterogeneous rate constant of the electrochemical reaction (ke), the slope of the d.c. polarogram log plot, and the magnitude of [varrho], the a.c. polarographic efficiency (ratio of the observed and theoretical magnitudes of the faradaic alternating current). The concentration ratio is not, however, the sole determining factor; the absolute concentrations also have an effect. The log plot is apparently a quite inadequate measure of reversibility; ke, which is a determining factor in the d.c. polarographic reversibility, is probably not functionally related to the thermodynamic reversibility of the electrode process; [varrho] could be a measure of the thermodynamic reversibility of the electrochemicaI process.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32416/1/0000495.pd

Against the Tide. A Critical Review by Scientists of How Physics and Astronomy Get Done

Nobody should have a monopoly of the truth in this universe. The censorship and suppression of challenging ideas against the tide of mainstream research, the blacklisting of scientists, for instance, is neither the best way to do and filter science, nor to promote progress in the human knowledge. The removal of good and novel ideas from the scientific stage is very detrimental to the pursuit of the truth. There are instances in which a mere unqualified belief can occasionally be converted into a generally accepted scientific theory through the screening action of refereed literature and meetings planned by the scientific organizing committees and through the distribution of funds controlled by "club opinions". It leads to unitary paradigms and unitary thinking not necessarily associated to the unique truth. This is the topic of this book: to critically analyze the problems of the official (and sometimes illicit) mechanisms under which current science (physics and astronomy in particular) is being administered and filtered today, along with the onerous consequences these mechanisms have on all of us.\ud \ud The authors, all of them professional researchers, reveal a pessimistic view of the miseries of the actual system, while a glimmer of hope remains in the "leitmotiv" claim towards the freedom in doing research and attaining an acceptable level of ethics in science

Clinical significance of immune-system laboratory tests

Anatomists and many other medical specialists rely on clinical laboratories for critical information to assist in diagnosis, prognosis, and the evaluation of treatments. However, the clinical laboratories do not always accompany their numbers with sufficient information about the significance of certain results: how great the quantitative variation of a given parameter might be in healthy subjects, and how likely it might be that a given qualitative (“yes” or “no”) result is a false positive or false negative. This situation has been particularly troublesome in the case of HIV, because there is no “gold standard” HIV test and the typically quantitated measure, CD4, varies widely for a variety of reasons that have nothing to do with HIV infection. For example, a person pronounced HIV-positive after having some vaccinations became HIV-negative again after a time, something that is not regarded as possible if HIV-positive denotes definitely active infection, as is commonly assumed. An important consequence of deficient information about HIV epidemiology is that students of anatomy may fear risking possible infection in dissection laboratories when the actual risk is negligible even in respect to anonymous cadavers in South Africa where the supposed incidence of HIV is particularly high. We have previously pointed to the need to improve HIV epidemiology and related public policy by recognizing and taking into account the weaknesses in HIV testing, which are the probable reason for at least some of the troubling conundrums and mutually contradictory data that seem inexplicable: conflicting estimates of HIV infections and of HIV-disease deaths from equally authoritative sources; apparently drastically different primary modes of transmission in different geographic regions; extreme racial disparities in HIV infection, with Asians and Asian Americans consistently less affected, by about one third, than white Americans, while black Americans are affected by as much as an order of magnitude more than white Americans. Testing uncertainties doubtless also contribute to the confusion as to whether certain conditions (e.g. lipodystrophy or nephropathy) should be described as HIV-associated or as AIDS-associated. In recent work we have found that the immune system, including CD4 counts, can be markedly enhanced by easily modified dietary supplementation that has none of the toxic side-effects of the antiretroviral drugs currently used in the attempt to elevate CD4 counts in HIV-positive people

Lyapunov spectral analysis of a nonequilibrium Ising-like transition

By simulating a nonequilibrium coupled map lattice that undergoes an Ising-like phase transition, we show that the Lyapunov spectrum and related dynamical quantities such as the dimension correlation length~$\xi_\delta$ are insensitive to the onset of long-range ferromagnetic order. As a function of lattice coupling constant~$g$ and for certain lattice maps, the Lyapunov dimension density and other dynamical order parameters go through a minimum. The occurrence of this minimum as a function of~$g$ depends on the number of nearest neighbors of a lattice point but not on the lattice symmetry, on the lattice dimensionality or on the position of the Ising-like transition. In one-space dimension, the spatial correlation length associated with magnitude fluctuations and the length~$\xi_\delta$ are approximately equal, with both varying linearly with the radius of the lattice coupling.Comment: 29 pages of text plus 15 figures, uses REVTeX macros. Submitted to Phys. Rev. E

Risk stratification by pre-operative cardiopulmonary exercise testing improves outcomes following elective abdominal aortic aneurysm surgery : a cohort study

Background: In 2009, the NHS evidence adoption center and National Institute for Health and Care Excellence (NICE) published a review of the use of endovascular aneurysm repair (EVAR) of abdominal aortic aneurysms (AAAs). They recommended the development of a risk-assessment tool to help identify AAA patients with greater or lesser risk of operative mortality and to contribute to mortality prediction. A low anaerobic threshold (AT), which is a reliable, objective measure of pre-operative cardiorespiratory fitness, as determined by pre-operative cardiopulmonary exercise testing (CPET) is associated with poor surgical outcomes for major abdominal surgery. We aimed to assess the impact of a CPET-based risk-stratification strategy upon perioperative mortality, length of stay and non-operative costs for elective (open and endovascular) infra-renal AAA patients. Methods: A retrospective cohort study was undertaken. Pre-operative CPET-based selection for elective surgical intervention was introduced in 2007. An anonymized cohort of 230 consecutive infra-renal AAA patients (2007 to 2011) was studied. A historical control group of 128 consecutive infra-renal AAA patients (2003 to 2007) was identified for comparison. Comparative analysis of demographic and outcome data for CPET-pass (AT ≥ 11 ml/kg/min), CPET-fail (AT < 11 ml/kg/min) and CPET-submaximal (no AT generated) subgroups with control subjects was performed. Primary outcomes included 30-day mortality, survival and length of stay (LOS); secondary outcomes were non-operative inpatient costs. Results: Of 230 subjects, 188 underwent CPET: CPET-pass n = 131, CPET-fail n = 35 and CPET-submaximal n = 22. When compared to the controls, CPET-pass patients exhibited reduced median total LOS (10 vs 13 days for open surgery, n = 74, P < 0.01 and 4 vs 6 days for EVAR, n = 29, P < 0.05), intensive therapy unit requirement (3 vs 4 days for open repair only, P < 0.001), non-operative costs (£5,387 vs £9,634 for open repair, P < 0.001) and perioperative mortality (2.7% vs 12.6% (odds ratio: 0.19) for open repair only, P < 0.05). CPET-stratified (open/endovascular) patients exhibited a mid-term survival benefit (P < 0.05). Conclusion: In this retrospective cohort study, a pre-operative AT > 11 ml/kg/min was associated with reduced perioperative mortality (open cases only), LOS, survival and inpatient costs (open and endovascular repair) for elective infra-renal AAA surgery

The X-ray luminous cluster underlying the z = 1.04 quasar PKS1229-021

We present a 100 ks Chandra observation studying the extended X-ray emission around the powerful z=1.04 quasar PKS1229-021. The diffuse cluster X-ray emission can be traced out to ~15 arcsec (~120 kpc) radius and there is a drop in the calculated hardness ratio inside the central 5 arcsec consistent with the presence of a cool core. Radio observations of the quasar show a strong core and a bright, one-sided jet leading to the SW hot spot and a second hot spot visible on the counter-jet side. Although the wings of the quasar PSF provided a significant contribution to the total X-ray flux at all radii where the extended cluster emission was detected, we were able to accurately subtract off the PSF emission using ChaRT and marx simulations. The resulting steep cluster surface brightness profile for PKS1229-021 appears similar to the profile for the FRII radio galaxy 3C444, which has a similarly rapid surface brightness drop caused by a powerful shock surrounding the radio lobes (Croston et al.). Using a model surface brightness profile based on 3C444, we estimated the total cluster luminosity for PKS1229-021 to be L_X ~ 2 x 10^{44} erg/s. We discuss the difficulty of detecting cool core clusters, which host bright X-ray sources, in high redshift surveys.Comment: 10 pages, 9 figures, accepted by MNRA

AIDS since 1984: No evidence for a new, viral epidemic – not even in Africa

Since the discoveries of a putative AIDS virus in 1984 and of millions of asymptomatic carriers in subsequent years, no general AIDS epidemic has occurred by 2011. In 2008, however, it has been proposed that between 2000 and 2005 the new AIDS virus, now called HIV, had killed 1.8 million South Africans at a steady rate of 300,000 per year and that anti-HIV drugs could have saved 330,000 of those. Here we investigate these claims in view of the paradoxes that HIV would cause a general epidemic in Africa but not in other continents, and a steady rather than a classical bell-shaped epidemic like all other new pathogenic viruses. Surprisingly, we found that South Africa attributed only about 10,000 deaths per year to HIV between 2000 and 2005 and that the South African population had increased by 3 million between 2000 and 2005 at a steady rate of 500,000 per year. This gain was part of a monotonic growth trajectory spanning from 29 million in 1980 to 49 million in 2008. During the same time Uganda increased from 12 to 31 million, and Sub-Saharan Africa as a whole doubled from 400 to 800 million, despite high prevalence HIV. We deduce from this demographic evidence that HIV is not a new killer virus. Based on a review of the known toxicities of antiretroviral drugs we like to draw the attention of scientists, who work in basic and clinical medical fields, including embryologists, to the need of rethinking the risk-and-benefit balance of antiretroviral drugs for pregnant women, newborn babies and all others who carry antibodies against HIV

Status of the CRESST Dark Matter Search

The CRESST experiment aims for a detection of dark matter in the form of WIMPs. These particles are expected to scatter elastically off the nuclei of a target material, thereby depositing energy on the recoiling nucleus. CRESST uses scintillating CaWO4 crystals as such a target. The energy deposited by an interacting particle is primarily converted to phonons which are detected by transition edge sensors. In addition, a small fraction of the interaction energy is emitted from the crystals in the form of scintillation light which is measured in coincidence with the phonon signal by a separate cryogenic light detector for each target crystal. The ratio of light to phonon energy permits the discrimination between the nuclear recoils expected from WIMPs and events from radioactive backgrounds which primarily lead to electron recoils. CRESST has shown the success of this method in a commissioning run in 2007 and, since then, further investigated possibilities for an even better suppression of backgrounds. Here, we report on a new class of background events observed in the course of this work. The consequences of this observation are discussed and we present the current status of the experiment.Comment: Proceedings of the 13th International Workshop on Low Temperature Detectors, 4 pages, 3 figure