5,537 research outputs found
Analysis of plasma-nitrided steels
The analysis of plasma nitrided steels can be divided to two main categories - structural and chemical. Structural analysis can provide information not only on the hardening mechanisms but also on the fundamental processes involved. Chemical analysis can be used to study the kinetics for the nitriding process and its mechanisms. In this paper preliminary results obtained by several techniques of both categories are presented and the applicability of those techniques to the analysis of plasma-nitrided steels is discussed
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Principles of appropriate antibiotic use for treatment of uncomplicated acute bronchitis: background.
The following principles of appropriate antibiotic use for adults with acute bronchitis apply to immunocompetent adults without complicating comorbid conditions, such as chronic lung or heart disease. The evaluation of adults with an acute cough illness or a presumptive diagnosis of uncomplicated acute bronchitis should focus on ruling out serious illness, particularly pneumonia. In healthy, nonelderly adults, pneumonia is uncommon in the absence of vital sign abnormalities or asymmetrical lung sounds, and chest radiography is usually not indicated. In patients with cough lasting 3 weeks or longer, chest radiography may be warranted in the absence of other known causes. Routine antibiotic treatment of uncomplicated acute bronchitis is not recommended, regardless of duration of cough. If pertussis infection is suspected (an unusual circumstance), a diagnostic test should be performed and antimicrobial therapy initiated. Patient satisfaction with care for acute bronchitis depends most on physician--patient communication rather than on antibiotic treatment
International Society of Sports Nutrition position stand: beta-alanine
Position statement: The International Society of Sports Nutrition (ISSN) provides an objective and critical review of the mechanisms and use of beta-alanine supplementation. Based on the current available literature, the conclusions of the ISSN are as follows: 1) Four weeks of beta-alanine supplementation (4–6 g daily) significantly augments muscle carnosine concentrations, thereby acting as an intracellular pH buffer; 2) Beta-alanine supplementation currently appears to be safe in healthy populations at recommended doses; 3) The only reported side effect is paraesthesia (tingling), but studies indicate this can be attenuated by using divided lower doses (1.6 g) or using a sustained-release formula; 4) Daily supplementation with 4 to 6 g of beta-alanine for at least 2 to 4 weeks has been shown to improve exercise performance, with more pronounced effects in open end-point tasks/time trials lasting 1 to 4 min in duration; 5) Beta-alanine attenuates neuromuscular fatigue, particularly in older subjects, and preliminary evidence indicates that beta-alanine may improve tactical performance; 6) Combining beta-alanine with other single or multi-ingredient supplements may be advantageous when supplementation of beta-alanine is high enough (4–6 g daily) and long enough (minimum 4 weeks); 7) More research is needed to determine the effects of beta-alanine on strength, endurance performance beyond 25 min in duration, and other health-related benefits associated with carnosine
Explorer 45 (S 3-A) observations of the magnetosphere and magnetopause during the 4-5 August 1972, magnetic storm period
The Explorer 45 satellite performed extensive field and particle measurements in the heart of the magnetosphere during the double magnetic storm period of August 4-5, 1972. Both ground level magnetic records and the magnetic field deformations measured along the orbit by the satellite indicated the existence of only a moderate ring current. This was confirmed by the measurements of the total proton energy density less than those observed during the December 1971 and June 1972 magnetic storms. The plasmapause in the noon quadrant was eroded continuously from the onset of the first storm at the beginning of August 4 to an altitude below L = 2.07 at about 18 hours on August 5. During the orbit containing the second sudden commencement a large amount of low frequency electric and magnetic field noise was encountered throughout the entire orbit. A noteworthy observation during this orbit was the contraction of the magnetopause to distances inside the satellite at L = 5.2
Ariel - Volume 4 Number 6
Editors
David A. Jacoby
Eugenia Miller
Tom Williams
Associate Editors
Paul Bialas
Terry Burt
Michael Leo
Gail Tenikat
Editor Emeritus and Business Manager
Richard J. Bonnano
Movie Editor
Robert Breckenridge
Staff
Richard Blutstein
Mary F. Buechler
J.D. Kanofsky
Rocket Weber
David Maye
Maintenance Procedure Display: Head Mounted Display (HMD) Evaluations
A viewgraph presentation describing maintenance procedures for head mounted displays is shown. The topics include: 1) Study Goals; 2) Near Eye Displays (HMDs); 3) Design; 4) Phase I-Evaluation Methods; 5) Phase 1 Results; 6) Improved HMD Mounting; 7) Phase 2 -Evaluation Methods; 8) Phase 2 Preliminary Results; and 9) Next Steps
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Macrophage migration inhibitory factor downregulation: a novel mechanism of resistance to anti-angiogenic therapy.
Anti-angiogenic therapies for cancer such as VEGF neutralizing antibody bevacizumab have limited durability. While mechanisms of resistance remain undefined, it is likely that acquired resistance to anti-angiogenic therapy will involve alterations of the tumor microenvironment. We confirmed increased tumor-associated macrophages in bevacizumab-resistant glioblastoma patient specimens and two novel glioblastoma xenograft models of bevacizumab resistance. Microarray analysis suggested downregulated macrophage migration inhibitory factor (MIF) to be the most pertinent mediator of increased macrophages. Bevacizumab-resistant patient glioblastomas and both novel xenograft models of resistance had less MIF than bevacizumab-naive tumors, and harbored more M2/protumoral macrophages that specifically localized to the tumor edge. Xenografts expressing MIF-shRNA grew more rapidly with greater angiogenesis and had macrophages localizing to the tumor edge which were more prevalent and proliferative, and displayed M2 polarization, whereas bevacizumab-resistant xenografts transduced to upregulate MIF exhibited the opposite changes. Bone marrow-derived macrophage were polarized to an M2 phenotype in the presence of condition-media derived from bevacizumab-resistant xenograft-derived cells, while recombinant MIF drove M1 polarization. Media from macrophages exposed to bevacizumab-resistant tumor cell conditioned media increased glioma cell proliferation compared with media from macrophages exposed to bevacizumab-responsive tumor cell media, suggesting that macrophage polarization in bevacizumab-resistant xenografts is the source of their aggressive biology and results from a secreted factor. Two mechanisms of bevacizumab-induced MIF reduction were identified: (1) bevacizumab bound MIF and blocked MIF-induced M1 polarization of macrophages; and (2) VEGF increased glioma MIF production in a VEGFR2-dependent manner, suggesting that bevacizumab-induced VEGF depletion would downregulate MIF. Site-directed biopsies revealed enriched MIF and VEGF at the enhancing edge in bevacizumab-naive patients. This MIF enrichment was lost in bevacizumab-resistant glioblastomas, driving a tumor edge M1-to-M2 transition. Thus, bevacizumab resistance is driven by reduced MIF at the tumor edge causing proliferative expansion of M2 macrophages, which in turn promotes tumor growth
QCD Strings as Constrained Grassmannian Sigma Model:
We present calculations for the effective action of string world sheet in R3
and R4 utilizing its correspondence with the constrained Grassmannian sigma
model. Minimal surfaces describe the dynamics of open strings while harmonic
surfaces describe that of closed strings. The one-loop effective action for
these are calculated with instanton and anti-instanton background, reprsenting
N-string interactions at the tree level. The effective action is found to be
the partition function of a classical modified Coulomb gas in the confining
phase, with a dynamically generated mass gap.Comment: 22 pages, Preprint: SFU HEP-116-9
Lunar Outgassing, Transient Phenomena and The Return to The Moon, I: Existing Data
Herein the transient lunar phenomena (TLP) report database is subjected to a
discriminating statistical filter robust against sites of spurious reports, and
produces a restricted sample that may be largely reliable. This subset is
highly correlated geographically with the catalog of outgassing events seen by
the Apollo 15, 16 and Lunar Prospector alpha-particle spectrometers for
episodic Rn-222 gas release. Both this robust TLP sample and even the larger,
unfiltered sample are highly correlated with the boundary between mare and
highlands, as are both deep and shallow moonquakes, as well as Po-210, a
long-lived product of Rn-222 decay and a further tracer of outgassing. This
offers another significant correlation relating TLPs and outgassing, and may
tie some of this activity to sagging mare basalt plains (perhaps mascons).
Additionally, low-level but likely significant TLP activity is connected to
recent, major impact craters (while moonquakes are not), which may indicate the
effects of cracks caused by the impacts, or perhaps avalanches, allowing
release of gas. The majority of TLP (and Rn-222) activity, however, is confined
to one site that produced much of the basalt in the Procellarum Terrane, and it
seems plausible that this TLP activity may be tied to residual outgassing from
the formerly largest volcanic ffusion sites from the deep lunar interior. With
the coming in the next few years of robotic spacecraft followed by human
exploration, the study of TLPs and outgassing is both promising and imperiled.
We will have an unprecedented pportunity to study lunar outgassing, but will
also deal with a greater burden of anthropogenic lunar gas than ever produced.
There is a pressing need to study lunar atmosphere and its sources while still
pristine. [Abstract abridged.]Comment: 35 pages, 3 figures, submitted to Icarus. Other papers in series
found at http://www.astro.columbia.edu/~arlin/TLP
Examination of a pre-exercise, high energy supplement on exercise performance
<p>Abstract</p> <p>Background</p> <p>The purpose of this study was to examine the effect of a pre-exercise high energy drink on reaction time and anaerobic power in competitive strength/power athletes. In addition, the effect of the pre-exercise drink on subjective feelings of energy, fatigue, alertness and focus was also explored.</p> <p>Methods</p> <p>Twelve male strength/power athletes (21.1 ± 1.3 y; 179.8 ± 7.1 cm; 88.6 ± 12.1 kg; 17.6 ± 3.3% body fat) underwent two testing sessions administered in a randomized and double-blind fashion. During each session, subjects reported to the Human Performance Laboratory and were provided with either 120 ml of a high energy drink (SUP), commercially marketed as Redline Extreme<sup>® </sup>or 120 ml of a placebo (PL) that was similar in taste and appearance but contained no active ingredients. Following consumption of the supplement or placebo subjects rested quietly for 10-minutes prior to completing a survey and commencing exercise. The survey consisted of 4 questions asking each subject to describe their feelings of energy, fatigue, alertness and focus for that moment. Following the completion of the questionnaire subjects performed a 2-minute quickness and reaction test on the Makoto testing device (Makoto USA, Centennial CO) and a 20-second Wingate Anaerobic Power test. Following a 10-minute rest subjects repeated the testing sequence and after a similar rest period a third and final testing sequence was performed. The Makoto testing device consisted of subjects reacting to both a visual and auditory stimulus and striking one out of 30 potential targets on three towers.</p> <p>Results</p> <p>Significant difference in reaction performance was seen between SUP and PL in both average number of targets struck (55.8 ± 7.4 versus 51.9 ± 7.4, respectively) and percent of targets struck (71.9 ± 10.5% versus 66.8 ± 10.9%, respectively). No significant differences between trials were seen in any anaerobic power measure. Subjective feelings of energy (3.5 ± 0.5 versus 3.1 ± 0.5) and focus (3.8 ± 0.5 versus 3.3 ± 0.7) were significantly higher during SUP compared to PL, respectively. In addition, a trend towards an increase in average alertness (p = 0.06) was seen in SUP compared to P.</p> <p>Conclusion</p> <p>Results indicate a significant increase in reaction performance, with no effect on anaerobic power performance. In addition, ingestion of this supplement significantly improves subjective feelings of focus and energy in male strength/power athletes.</p
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