12,683 research outputs found
Rotational CARS application to simultaneous and multiple-point temperature and concentration determination in a turbulent flow
Coherent anti-Stokes Raman scattering (CARS) from the pure rotational Raman lines of N2 is employed to measure the instantaneous (approximately 10 ns) rotational temperature of N2 gas at room temperature and below with good spatial resolution (0.2 x 0.2 x 3.0 cu mm). A broad bandwidth dye laser is used to obtain the entire rotational spectrum from a single laser pulse; the CARS signal is then dispersed by a spectrograph and recorded on an optical multichannel analyzer. A best fit temperature is found in several seconds with the aid of a computer for each experimental spectrum by a least squares comparison with calculated spectra. The model used to calculate the theoretical spectra incorporates the temperature and pressure dependence of the pressure-broadened rotational Raman lines, includes the nonresonant background susceptibility, and assumes that the pump laser has a finite linewidth. Temperatures are fit to experimental spectra recorded over the temperature range of 135 to 296 K, and over the pressure range of .13 to 15.3 atm
Admission Diagnosis of Cerebral Malaria in Adults in an Endemic Area of Tanzania:Implications and Clinical Description
Cerebralmalariais commonly diagnosed in adults in endemic areas in Africa, both in hospitals and in the community. This presents a paradox inconsistent with the epidemiological understanding that the development of immunity during childhood confers protection against severe disease in adult life. To establish the contribution of Plasmodium falciparum infection in adults admitted with neurological dysfunction in an endemic area, to assess the implications of an admission clinical diagnosis of ‘cerebral malaria’ on the treatment and clinical outcome, and to describe the clinical features of patients with malaria parasitaemia. Prospective observational study. We studied adult patients admitted with neurological dysfunction to Muhimbili National Hospital, Dar-es-Salaam, Tanzania from October 2000 to July 2001. A full blood count was done and serum creatinine, blood glucose and P. falciparum parasite load were measured. Of 199 patients (median age 34.5 years), 38% were diagnosed as ‘cerebral malaria’ on admission, but only 7.5% had detectable parasitaemia, giving a positive predictive value of 13.3%. Only 1% fulfilled the WHO criteria for cerebral malaria. The prevalence of parasitaemia (7.5%) was less than that observed in a group of asymptomatic controls (9.3%), but distribution of parasite densities was higher in the patients. Mortality was higher in patients with no parasitaemia (22.3%) than in those with parasitaemia (13%). Cerebral malaria was grossly overdiagnosed, resulting in unnecessary treatment and insufficient investigation of other possible diagnoses, which could lead to higher mortality. Extension of this misperception to the assessment of cause of death in community surveys may lead to an overestimation of the impact of malaria in adults.\u
New Insights on Interstellar Gas-Phase Iron
In this paper, we report on the gas-phase abundance of singly-ionized iron
(Fe II) for 51 lines of sight, using data from the Far Ultraviolet
Spectroscopic Explorer (FUSE). Fe II column densities are derived by measuring
the equivalent widths of several ultraviolet absorption lines and subsequently
fitting those to a curve of growth. Our derivation of Fe II column densities
and abundances creates the largest sample of iron abundances in moderately- to
highly-reddened lines of sight explored with FUSE, lines of sight that are on
average more reddened than lines of sight in previous Copernicus studies. We
present three major results. First, we observe the well-established correlation
between iron depletion and and also find trends between iron depletion
and other line of sight parameters (e.g. f(H_2), E_(B-V), and A_V), and examine
the significance of these trends. Of note, a few of our lines of sight probe
larger densities than previously explored and we do not see significantly
enhanced depletion effects. Second, we present two detections of an extremely
weak Fe II line at 1901.773 A in the archival STIS spectra of two lines of
sight (HD 24534 and HD 93222). We compare these detections to the column
densities derived through FUSE spectra and comment on the line's f-value and
utility for future studies of Fe II. Lastly, we present strong anecdotal
evidence that the Fe II f-values derived empirically through FUSE data are more
accurate than previous values that have been theoretically calculated, with the
probable exception of f_1112.Comment: Accepted for publication in ApJ, 669, 378; see ApJ version for small
updates. 53 total pages (preprint format), 7 tables, 11 figure
Processing and Transmission of Information
Contains reports on four research projects.National Science Foundation (Grant G-16526)National Institutes of Health (Grant MH-04737-03)National Aeronautics and Space Administration (Grant NsG-496)Lincoln Laboratory (Purchase Order DDL BB-107)United States Air Force (Contract AF19(628)-500
Estrogenic Compounds Downstream from Three Small Cities in Eastern Nebraska: Occurrence and Biological Effect
Recent studies have detected estrogenic compounds in surface waters in North America and Europe. Furthermore, the presence of estrogenic compounds in surface waters has been attributed, in some cases, to the discharge of wastewater treatment plant (WWTP) effluent. The primary objective of the current study was to determine if WWTP effluent contributes estrogens to the surface waters of Nebraska. A second objective of this study was to determine if estrogens were found in concentrations sufficient enough to manifest feminizing effects on fish. These objectives were satisfied by deploying polar organic chemical integrative samplers (POCIS) and caged fathead minnows at eight field sites. Deployment sites included: three reference sites (Pawnee Creek, the Little Blue River, and the Middle Loup River), two sites upstream of the WWTPs at Grand Island and Columbus, and three sites downstream of the WWTPs at Grand Island, Columbus, and Hastings. Following the seven day deployments, POCIS extracts were analyzed for estrone, 17β-estradiol, estriol and 17α-ethinylestradiol using liquid chromatography tandem mass spectrometry (LC/MS/MS). 17β-estradiol was detected in POCIS from six of the eight field sites with the greatest quantities recovered in POCIS deployed downstream from the Grand Island and Hastings WWTPs. Estrone was detected only in the POCIS deployed downstream from the Grand Island and Hastings WWTPs. Estrogenic effects were detected in caged minnows analyzed for the hepatic mRNA expression of two estrogen- responsive genes, vitellogenin (vg1) and estrogen receptor α (ERα). Fish deployed at the site where the greatest quantities of estrogens were recovered (Hastings) had significantly higher expression of both vg1 and ERα than fish deployed at any of the other sites. These results confirm that WWTP effluent contributes biologically significant levels of estrogens to Nebraska surface waters
Young children's cognitive achievement: home learning environment, language and ethnic background
For decades, research has shown differences in cognitive assessment scores between White and minority ethnic group(s) learners as well as differences across different minority ethnic groups. More recent data have indicated that the home learning environment and languages spoken can impact cognitive assessment and other corollary outcomes. This study uses the Millennium Cohort Study to jointly assess how minority ethnic group, home learning environment and home languages predict child cognitive assessment scores. Regression analyses were conducted using two assessment measures. The following is hypothesised: (1) cognitive achievement scores vary by minority ethnic group, (2) more home learning environment in early childhood leads to higher cognitive development scores and (3) English only in the home yields the highest cognitive scores while no English in the home yields the lowest. Findings reveal that there are differences in cognitive scores along ethnic group categories although there are also some unexpected findings. Home learning environment does not play as large a role as was predicted in raising the assessment scores overall for learners while speaking English in the home does, irrespective of ethnic background
Report of the QCD Tools Working Group
We report on the activities of the ``QCD Tools for heavy flavors and new
physics searches'' working group of the Run II Workshop on QCD and Weak Bosons.
The contributions cover the topics of improved parton showering and comparisons
of Monte Carlo programs and resummation calculations, recent developments in
Pythia, the methodology of measuring backgrounds to new physics searches,
variable flavor number schemes for heavy quark electro-production, the
underlying event in hard scattering processes, and the Monte Carlo MCFM for NLO
processes.Comment: LaTeX, 47 pages, 41 figures, 10 tables, uses run2col.sty, to appear
in the Proceedings of the Workshop on "QCD and Weak Boson Physics in Run II",
Fermilab, March - November 199
Decoupling of a Neutron Interferometer from Temperature Gradients
Neutron interferometry enables precision measurements that are typically
operated within elaborate, multi-layered facilities which provide substantial
shielding from environmental noise. These facilities are necessary to maintain
the coherence requirements in a perfect crystal neutron interferometer which is
extremely sensitive to local environmental conditions such as temperature
gradients across the interferometer, external vibrations, and acoustic waves.
The ease of operation and breadth of applications of perfect crystal neutron
interferometry would greatly benefit from a mode of operation which relaxes
these stringent isolation requirements. Here, the INDEX Collaboration and
National Institute of Standards and Technology demonstrates the functionality
of a neutron interferometer in vacuum and characterize the use of a compact
vacuum chamber enclosure as a means to isolate the interferometer from spatial
temperature gradients and time-dependent temperature fluctuations. The vacuum
chamber is found to have no depreciable effect on the performance of the
interferometer (contrast) while improving system stability, thereby showing
that it is feasible to replace large temperature isolation and control systems
with a compact vacuum enclosure for perfect crystal neutron interferometry
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