5,727 research outputs found
Space processes for extended low-G testing
Results of an investigation of verifying the capabilities of space processes in ground based experiments at low-g periods are presented. Limited time experiments were conducted with the processes. A valid representation of the complete process cycle was achieved at low-g periods ranging from 40 to 390 seconds. A minimum equipment inventory, is defined. A modular equipment design, adopted to assure low cost and high program flexibility, is presented as well as procedures and data established for the synthesis and definition of dedicated and mixed rocket payloads
Measurements and comparison of primary biological aerosol above and below a tropical forest canopy using a dual channel fluorescence spectrometer
Original article can be found at: http://www.atmos-chem-phys.net/10/issue10.html Copyright - the authors. Authors grant any third party the right to use the article freely as long as its original authors and citation details are identified. The article and any associated published material is distributed under the Creative Commons Attribution 3.0 License.Aerosol particle size distributions were measured below and above a tropical rainforest canopy in Borneo, Malaysia, in June/July 2008 using the WIBS-3: a single particle dual channel fluorescence spectrometer. Material in the size range 0.8–20 μm was characterized according to optical equivalent diameter (DP), morphology and fluorescence at 310–400 nm and 400–600 nm following excitation at 280 nm and 370 nm respectively. Particles fluorescent after both excitations are likely to be fluorescent primary biological aerosol particles (FBAP). Measured FBAP number concentration (NFBAP) at both sites exhibited clear diurnal cycles. The largest variability was observed in the understorey, where NFBAP reached a minimum of 50–100 L−1 in late morning. In mid afternoon it exhibited strong transient fluctuations as large as 4000 L−1 that were followed by sustained concentrations of 1000–2500 L−1 that reduced steadily between midnight and sunrise. Above the canopy FBAP number ranged from 50–100 L−1 during the daytime to 200–400 L−1 at night but did not exhibit the transient enhancements seen in the understorey. The strong FBAP fluctuations were attributed to the release of fungal spores below the canopy and appeared to be linked to elevated relative humidity. The mean FBAP number fraction in the size range 0.8 μm<DP<20 μm was 55% in the understorey and 28% above canopy. A size mode at 2 μm<DP<4 μm appears at both sites and is primarily FBAP, which dominated the coarse (DP≥2.5 μm) number concentration at both sites, accounting for 75% in the understorey and 57% above the canopy. In contrast, the concentration of non-fluorescent particles (NNON) at both sites was typically 200–500 L−1, the majority of which occupied a size mode at 0.8<DP<1.5 μm. Enhanced understorey NNON was observed daily in mid-afternoon and also at midday on three occasions: the former coincided with the FBAP enhancements and measured approximately 10% of their magnitude; the latter occurred independently of the NFBAP diurnal cycle and comprised particles smaller than 2 μm. Particle diameter of 3–5 μm is consistent with smaller fungal spores, though absolute identification of biological species is not possible with the UV-LIF technique. Based on the measured FBAP and non-fluorescent particle abundances and their observed recovery times following rain showers, FBAP originated beneath the canopy while the non-fluorescent material was transported from further away. It is concluded that these separate sources contributed the majority of the aerosol measured by the WIBS-3 at both sites.Peer reviewe
DNA Typing: Emerging or Neglected Issues
DNA typing has had a major impact on the criminal justice system. There are hundreds of opinions and thousands of cases dealing with DNA evidence. Yet, at virtually every stage of the process, there are important issues that are just emerging or that have been neglected.At the investigative stage, courts have barely begun to focus on the legal limitations on the power of the police to obtain samples directly from suspects and to use the data from DNA samples in various ways. Issues such as the propriety of DNA dragnets (in which large numbers of individuals in a geographic area are asked to provide samples voluntarily), the validity of court orders for samples based on a lesser standard than probable cause, and the permissibility of collecting DNA abandoned in public places are being litigated for the first time. Using crime-scene samples to infer racial or ethnic characteristics is emerging as a distinct possibility. Then there are the more than 282 million specimens of human biological material stored by private and public agencies in the United States; in some situations, police may well turn to some of these repositories to obtain samples. There is little or no case law analyzing the constitutional restrictions on these investigative practices.After the filing of charges, an accused sometimes moves to dismiss on the ground of the expiration of the statute of limitations. However, there is a movement to carve out a DNA exception to the statute of limitations in cases in which DNA evidence permits the identification of the perpetrator after the expiration of the normal period of limitations. The argument is that the legislative purpose of the statute is to prevent the maintenance of prosecutions based on stale, unreliable evidence but that DNA evidence is so reliable that its availability should lift the bar of the statute. However, little attention has been given to the difficulties inherent in drafting such a legislative exception that will not be overinclusive.At the trial stage, in a growing number of cases, after the defense attacks the weight of the government\u27s DNA evidence, prosecutors are commenting to the jury that the defense has requested an opportunity to retest the DNA. Do such comments run afoul of the Fifth or Sixth Amendment?The purpose of this Article is to identify and analyze such emerging issues. If the criminal justice system is to realize the full potential of DNA technology while maintaining the essential fairness of the system, it must come to grips with these issues in short order
DNA Typing: Emerging or Neglected Issues
DNA typing has had a major impact on the criminal justice system. There are hundreds of opinions and thousands of cases dealing with DNA evidence. Yet, at virtually every stage of the process, there are important issues that are just emerging or that have been neglected.At the investigative stage, courts have barely begun to focus on the legal limitations on the power of the police to obtain samples directly from suspects and to use the data from DNA samples in various ways. Issues such as the propriety of DNA dragnets (in which large numbers of individuals in a geographic area are asked to provide samples voluntarily), the validity of court orders for samples based on a lesser standard than probable cause, and the permissibility of collecting DNA abandoned in public places are being litigated for the first time. Using crime-scene samples to infer racial or ethnic characteristics is emerging as a distinct possibility. Then there are the more than 282 million specimens of human biological material stored by private and public agencies in the United States; in some situations, police may well turn to some of these repositories to obtain samples. There is little or no case law analyzing the constitutional restrictions on these investigative practices.After the filing of charges, an accused sometimes moves to dismiss on the ground of the expiration of the statute of limitations. However, there is a movement to carve out a DNA exception to the statute of limitations in cases in which DNA evidence permits the identification of the perpetrator after the expiration of the normal period of limitations. The argument is that the legislative purpose of the statute is to prevent the maintenance of prosecutions based on stale, unreliable evidence but that DNA evidence is so reliable that its availability should lift the bar of the statute. However, little attention has been given to the difficulties inherent in drafting such a legislative exception that will not be overinclusive.At the trial stage, in a growing number of cases, after the defense attacks the weight of the government\u27s DNA evidence, prosecutors are commenting to the jury that the defense has requested an opportunity to retest the DNA. Do such comments run afoul of the Fifth or Sixth Amendment?The purpose of this Article is to identify and analyze such emerging issues. If the criminal justice system is to realize the full potential of DNA technology while maintaining the essential fairness of the system, it must come to grips with these issues in short order
X-ray emission from the remarkable A-type star HR 8799
We present a Chandra observation of the exceptional planet bearing A5V star
HR 8799, more precisely classified as a kA5hF0mA5 star and search for intrinsic
X-ray emission. We clearly detect HR 8799 at soft X-ray energies with the
ACIS-S detector in a 10 ks exposure; minor X-ray brightness variability is
present during the observation. The coronal plasma is described well by a model
with a temperature of around 3 MK and an X-ray luminosity of about Lx = 1.3 x
10^28 erg/s in the 0.2-2.0 keV band, corresponding to an activity level of log
Lx/Lbol ~ -6.2. Altogether, these findings point to a rather weakly active and
given a RASS detection, long-term stable X-ray emitting star. The X-ray
emission from HR 8799 resembles those of a late A/early F-type stars, in
agreement with its classification from hydrogen lines and effective temperature
determination and thus resolving the apparent discrepancy with the standard
picture of magnetic activity that predicts mid A-type stars to be virtually
X-ray dark.Comment: 4 pages, 3 figures, accepted by A&
Incidence of rough and irregular atmospheric ice particles from Small Ice Detector 3 measurements
NERC, NE/E011225/1 © Author(s) 2013. This work is distributed under the Creative Commons Attribution 3.0 LicenseThe knowledge of properties of ice crystals such as size, shape, concavity and roughness is critical in the context of radiative properties of ice and mixed phase clouds. Limitations of current cloud probes to measure these properties can be circumvented by acquiring two-dimensional light scattering patterns instead of particle images. Such patterns were obtained in situ for the first time using the Small Ice Detector 3 (SID-3) probe during several flights in a variety of mid-latitude mixed phase and cirrus clouds. The patterns are analyzed using several measures of pattern texture, selected to reveal the magnitude of particle roughness or complexity. The retrieved roughness is compared to values obtained from a range of well-characterized test particles in the laboratory. It is found that typical in situ roughness corresponds to that found in the rougher subset of the test particles, and sometimes even extends beyond the most extreme values found in the laboratory. In this study we do not differentiate between small-scale, fine surface roughness and large-scale crystal complexity. Instead, we argue that both can have similar manifestations in terms of light scattering properties and also similar causes. Overall, the in situ data is consistent with ice particles with highly irregular or rough surfaces being dominant. Similar magnitudes of roughness were found in growth and sublimation zones of cirrus. The roughness was found to be negatively correlated with the halo ratio, but not with other thermodynamic or microphysical properties found in situ. Slightly higher roughness was observed in cirrus forming in clean oceanic airmasses than in a continental, polluted one. Overall, the roughness and complexity is expected to lead to increased shortwave cloud reflectivity, in comparison with cirrus composed of more regular, smooth ice crystal shapes. These findings put into question suggestions that climate could be modified through aerosol seeding to reduce cirrus cover and optical depth, as the seeding may result in decreased shortwave reflectivity.Peer reviewe
An Enhanced Nonlinear Critical Gradient for Electron Turbulent Transport due to Reversed Magnetic Shear
The first nonlinear gyrokinetic simulations of electron internal transport
barriers (e-ITBs) in the National Spherical Torus Experiment show that reversed
magnetic shear can suppress thermal transport by increasing the nonlinear
critical gradient for electron-temperature-gradient-driven turbulence to three
times its linear critical value. An interesting feature of this turbulence is
nonlinearly driven off-midplane radial streamers. This work reinforces the
experimental observation that magnetic shear is likely an effective way of
triggering and sustaining e-ITBs in magnetic fusion devices.Comment: 4 pages, 5 figure
An Enhanced Nonlinear Critical Gradient for Electron Turbulent Transport due to Reversed Magnetic Shear
The first nonlinear gyrokinetic simulations of electron internal transport
barriers (e-ITBs) in the National Spherical Torus Experiment show that reversed
magnetic shear can suppress thermal transport by increasing the nonlinear
critical gradient for electron-temperature-gradient-driven turbulence to three
times its linear critical value. An interesting feature of this turbulence is
nonlinearly driven off-midplane radial streamers. This work reinforces the
experimental observation that magnetic shear is likely an effective way of
triggering and sustaining e-ITBs in magnetic fusion devices.Comment: 4 pages, 5 figure
Investigating the relationship between HIV testing and risk behaviour in Britain: National Survey of Sexual Attitudes and Lifestyles 2000.
OBJECTIVES: To estimate the prevalence of, and identify factors associated with, HIV testing in Britain. DESIGN: A large, stratified probability sample survey of sexual attitudes and lifestyles. METHODS: A total of 12,110 16-44 year olds completed a computer-assisted face-to-face interview and self-interview. Self-reports of HIV testing, i.e. the timing, reasons for and location of testing, were included. RESULTS: A total of 32.4% of men and 31.7% of women reported ever having had an HIV test, the majority of whom were tested through blood donation. When screening for blood donation and pregnancy were excluded, 9.0% of men and 4.6% of women had had a voluntary confidential HIV test (VCT) in the past 5 years. However, one third of injecting drug users and men who have sex with men had a VCT in the past 5 years. VCT in the past 5 years was significantly associated with age, residence, ethnicity, self-perceived HIV risk, reporting greater numbers of sexual partners, new sexual partners from abroad, previous sexually transmitted infection diagnosis, and injecting non-prescribed drugs for men and women, and same-sex partners (men only). Whereas sexually transmitted disease clinics were important sites for VCT, general practice accounted for almost a quarter of VCT. CONCLUSION: HIV testing is relatively common in Britain; however, it remains largely associated with population-based blood donation and antenatal screening programmes. In contrast, VCT remains highly associated with high-risk (sexual or drug-injecting) behaviours or population sub-groups at high risk. Strategies to reduce undiagnosed prevalent HIV infection will require further normalization and wider uptake of HIV testing
Contribution of a Real Depth Distance Stereoacuity Test to Clinical Management
Measurement of Stereopsis forms an important part of the clinical assessment of patients with disorders of ocular motility. The introduction of a real depth distance stereoacuity test (FD2) was evaluated in clinical practice and to what extent the introduction affected clinical management. Seventy-three patients under evaluation before and following the introduction of the test were included. Combined thresholds were measured at near using the Frisby and TNO test and at distance using the FD2. Fifty healthy controls were included. Forty-five patients demonstrated Stereopsis using the FD2 and 23 of these had a change in their management based in part on their responses using the FD2. Patients with evidence of Stereopsis using the FD2 were significantly more likely to have change in their management than expected from the whole sample (P = .02). The introduction of a real depth distance stereoacuity test into clinical practice contributed to a change in management when used in conjunction with other tests. The usefulness of the FD2 is limited by its range at 6 m. Use at closer distances necessitates the calculation of binocular threshold from the combined and monocular threshold
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