Overcoming the false-minima problem in direct methods: Structure determination of the packaging enzyme P4 from bacteriophage φ13

The problems encountered during the phasing and structure determination of the packaging enzyme P4 from bacteriophage φ13 using the anomalous signal from selenium in a single-wavelength anomalous dispersion experiment (SAD) are described. The oligomeric state of P4 in the virus is a hexamer (with sixfold rotational symmetry) and it crystallizes in space group C2, with four hexamers in the crystallographic asymmetric unit. Current state-of-the-art ab initio phasing software yielded solutions consisting of 96 atoms arranged as sixfold symmetric clusters of Se atoms. However, although these solutions showed high correlation coefficients indicative that the substructure had been solved, the resulting phases produced uninterpretable electron-density maps. Only after further analysis were correct solutions found (also of 96 atoms), leading to the eventual identification of the positions of 120 Se atoms. Here, it is demonstrated how the difficulties in finding a correct phase solution arise from an intricate false-minima problem. © 2005 International Union of Crystallography - all rights reserved

Accuracy of the Omron HBF-500 Body Composition Monitor in Male and Female College Students

The Omron HBF-500 is an inexpensive body composition monitor that incorporates both hand-to-hand and foot-to-foot electrical impedance technology. At this time, studies examining the accuracy of the HBF-500 when estimating percent body fat (%BF) are scarce and if this instrument gains popularity due to its claimed precision, comparisons against validated techniques should be conducted. The purpose of this study was to assess the accuracy of the Omron HBF-500 body composition monitor using the BOD POD as a criterion. Forty-eight men and 33 women participated in the study (24.3±6.9 years, 171.0±10.0 cm, 78.4±18.0 kg, 26.6±5.1 kg/m2). Participants were asked to refrain from exercise and caffeine on the day of testing, not eat a heavy meal three hours prior to measurement (a meal that would typically constitute breakfast, lunch or dinner), and to remain normally hydrated. Participants removed all jewelry and garments down to skintight clothing such as swimsuits or cycling shorts and were assessed on the BOD POD and Omron according to manufacturer’s guidelines. The Omron significantly overestimated %BF compared to the BOD POD in males (24.4±8.0 % and 22.9±9.1 %, respectively), and females (35.5±7.7 % and 30.1±7.9 %), p = .001. The Omron was significantly correlated with the BOD POD when assessing body fat, r= .95. The estimates of %BF produced by the BOD POD and HBF-500 differ considerably. Consequently, caution should be taken when using the Omron HBF-500 as a measure of body fat. However, given the difference of only 1.5% BF between the two methods, perhaps males could use the HBF-500 to gain a general idea of body composition status. For females, the degree of overestimation is too high to be suitable for this purpose and incorrect categorization of %BF status could result. In cases where an accurate estimate of %BF is crucial, using a more established method than the Omron is recommended

Infrared imaging applied to the forensic examination of automotive paint

In a vehicle related fatality, paint fragments in the form of a chip are often transferred from the vehicle to the clothing of a pedestrian or an object such as a post. To analyze these paint fragments, a new approach to automotive paint analysis has been developed which is described in this honor's thesis. The new approach to forensic automotive paint analysis involves cross sectioning the paint chip with a microtome and then collecting infrared spectra from the entire chip in a single analysis by scanning across each layer using a transmission or attenuated total reflection (ATR) infrared microscope. After the spectral data from the microscope is collected, the data is then subject to decatenation using alternating least squares to extract the "pure" infrared (IR) spectrum of each layer from the image. Cross-sectioning the paint sample eliminates the need to analyze each paint layer separately and is faster than current methods which involve hand sectioning each layer. The use of spectal imaging can ensure that an IR spectrum of each paint layer is "pure" and is not a blend of multiple layers. The benefit of not collecting a mixed IR spectrum is higher quality matches when performing searches against the paint data query (PDQ) or other forensic automotive paint databases. Using this proposed approach, IR spectra of the clear coat, color coat, surfacer-primer, and e-coat layers were collected in a single analysis from a multi-layered automotive paint chip or paint smear using a transmission infrared imaging microscope. Decatenation of the spectral image as represented by a line map was achieved using alternating least squares. The successful spectral reconstructions of each layer allowed us to quantify the discrimination power of the original manufacturer's automotive paint system by way of a library search. The research described in this honors thesis will serve to quantify the general discrimination power of automotive paint comparisons involving both paint chips and paint smears and further efforts to succinctly communicate the significance of this evidence to the courts. This research will also ensure that analytical techniques used by paint examiners in forensic laboratories will remain current with respect to modern automotive paint systems

Extending HIV Prevention: People Living With HIV/AIDS (PLWHA) Strategize to Reduce Stigma and Promote HIV Testing

Strategies to reduce acquired immunodeficiency syndrome (AIDS)‐related stigma are paramount to promoting effective HIV prevention. As in the case of HIV antibody testing, despite the benefits of early detection, links to care, and risk behavior modification, nearly 250,000 people are unaware of their HIV status. AIDS‐related stigma has impeded such efforts due to discrimination, ignorance and other forms of stigma. These issues related to stigma and HIV testing are magnified when placed in the context of the rural Deep South region of the United States, where the incidence of HIV/AIDS are growing at alarming rates. The purpose of this paper was to examine strategies to reduce AIDS‐related stigma that in turn promotes HIV testing as proposed by people living with HIV/AIDS (PLWHA) who reside in the Deep South. An exploratory descriptive qualitative research design was utilized. The sample consisted of 18 PLWHA. Data was collected using a focus group and individual, semi‐structured interviews. The analysis revealed the importance of ongoing education as a mediator between reducing stigma and promoting HIV testing. Other salient findings were related to reframing HIV/AIDS‐related health messages to reflect a sense of empowerment; the need to normalize testing; the use of less stigmatizing testing sites; and the continuance of anonymous HIV testing. This article is significant because it illuminates the challenges of HIV prevention in the Deep South, while also generating culturally‐sensitive strategies to counter these barriers

Microwave Absorption of Surface-State Electrons on Liquid 3^3He

We have investigated the intersubband transitions of surface state electrons (SSE) on liquid $^3$He induced by microwave radiation at temperatures from 1.1 K down to 0.01 K. Above 0.4 K, the transition linewidth is proportional to the density of $^3$He vapor atoms. This proportionality is explained well by Ando's theory, in which the linewidth is determined by the electron - vapor atom scattering. However, the linewidth is larger than the calculation by a factor of 2.1. This discrepancy strongly suggests that the theory underestimates the electron - vapor atom scattering rate. At lower temperatures, the absorption spectrum splits into several peaks. The multiple peak structure is partly attributed to the spatial inhomogeneity of the static holding electric field perpendicular to the electron sheet.Comment: 15 pages, 7 figures, submitted to J. Phys. Soc. Jp

How to keep up wellbeing during the pandemic

World experts talk about what social isolation does, and what people can do to improve their wellbeing - by Tony Beaton, Ada Ferrer-i-Carbonell, Paul Frijters, Arthur Grimes, and Eugenio Prot

Accuracy of the Omron HBF-500 Body Composition Monitor

The Omron HBF-500 is a relatively new and inexpensive body composition monitor that incorporates both hand-to-hand and foot-to-foot electrical impedance technology. At this time, the authors are not aware of any studies examining the accuracy of this monitor. PURPOSE: To assess the accuracy of the Omron HBF-500 body composition monitor using the BOD POD as a criterion. METHODS: Sixteen men and 23 women signed an informed consent and participated in the study (22.7±3.7 years, 168.8±9.1 cm, 73.8±17.8 kg, 25.7±5.6 kg.m-2). Participants were asked to refrain from exercise and caffeine on the day of testing, and were asked not eat a heavy meal three hours prior and to remain normally hydrated. Participants removed all jewelry and garments down to tight fitting clothing (swim suits or running tights) and were assessed on the BOD POD and Omron according to manufacturer’s guidelines. RESULTS: The Omron HBF-500 significantly overestimated percent body fat (%BF) by 3.5% compared to the BOD POD (31.7±9.6% and 28.6±9.6%, respectively), t(38) = -6.05, p = 0.001. The Omron HBF-500 also measured weight significantly higher than the BODPOD (74.4±17.7kg and 73.8±17.8kg, respectively), t(38) = -11.2, p = 0.001. Finally, the Omron HBF-500 was significantly correlated with the BOD POD when assessing body fat, r = .93. CONCLUSIONS: Caution should be taken when using the Omron HBF-500 as a measure of body fat. Those who choose to use this instrument should be aware the 3.5% higher reading compared to the BOD POD

Influence of retardation effects on 2D magnetoplasmon spectrum

Within dissipationless limit the magnetic field dependence of magnetoplasmon spectrum for unbounded 2DEG system found to intersect the cyclotron resonance line, and, then approaches the frequency given by light dispersion relation. Recent experiments done for macroscopic disc-shape 2DEG systems confirm theory expectations.Comment: 2 pages,2 figure

The TAMORA algorithm: satellite rainfall estimates over West Africa using multi-spectral SEVIRI data

A multi-spectral rainfall estimation algorithm has been developed for the Sahel region of West Africa with the purpose of producing accumulated rainfall estimates for drought monitoring and food security. Radar data were used to calibrate multi-channel SEVIRI data from MSG, and a probability of rainfall at several different rain-rates was established for each combination of SEVIRI radiances. Radar calibrations from both Europe (the SatPrecip algorithm) and Niger (TAMORA algorithm) were used. 10 day estimates were accumulated from SatPrecip and TAMORA and compared with kriged gauge data and TAMSAT satellite rainfall estimates over West Africa. SatPrecip was found to produce large overestimates for the region, probably because of its non-local calibration. TAMORA was negatively biased for areas of West Africa with relatively high rainfall, but its skill was comparable to TAMSAT for the low-rainfall region climatologically similar to its calibration area around Niamey. These results confirm the high importance of local calibration for satellite-derived rainfall estimates. As TAMORA shows no improvement in skill over TAMSAT for dekadal estimates, the extra cloud-microphysical information provided by multi-spectral data may not be useful in determining rainfall accumulations at a ten day timescale. Work is ongoing to determine whether it shows improved accuracy at shorter timescales