9,885 research outputs found
Race, Drug Use, and the Justice System
A great deal of research concludes that drug use is relatively similar across races for adults, and that men use more than women. The current study makes use of self-report delinquency surveys of students in a South Dakota State University Juvenile Delinquency course and a California State University, San Bernardino Juvenile Justice course to determine if these trends also apply to juveniles. The current study will examine race and gender trends as they relate to illicit substance use in juveniles
The Natural and Cultural Landscape of Greene County, Virginia
One hundred and fifty five miles west of the Atlantic coast a sign welcomes travelers to Greene County, Virginia. The natural landscape of the region is defined by the transition between the flattish Piedmont plateau and natural wall to the west known as the Blue Ridge Mountains. The lushly forested mountain slopes and nutrient rich upland soils have long provided economic and cultural foundations, but indiscriminate land use now offers multiple threats to the rural heritage of the County. Overtimbered mountain slopes and multiple pollutants have threatened the immune systems of the forest, leaving them vulnerable to natural pests. Soils which once provided the foundation for an agrarian culture were often depleted, and now serve as the nutrients for expansive real estate development. The common threads that once helped to define the community are disappearing in the wake of rampant population growth. While a native community struggles to find its voice amongst an influx of new settlers, the natural resources of the region are diminishing.
This paper surveys the natural and human history of the region. It is the authors intent to identify that which threatens the natural and cultural landscape of Greene County. The paper also considers the success or failure of intervention strategies aimed at solving the identified problems, while recording the response of community members to such threats
Conceptual study of an advanced supersonic technology transport (AST-107) for transpacific range using low-bypass-ratio turbofan engines
An advanced supersonic technology configuration concept designated the AST-107, using a low bypass ratio turbofan engine, is described and analyzed. The aircraft had provisions for 273 passengers arranged five abreast. The cruise Mach number was 2.62. The mission range for the AST-107 was 8.48 Mm (4576 n.mi.) and an average lift drag ratio of 9.15 during cruise was achieved. The available lateral control was not sufficient for the required 15.4 m/s (30 kt) crosswind landing condition, and a crosswind landing gear or a significant reduction in dihedral effect would be necessary to meet this requirement. The lowest computed noise levels, including a mechanical suppressor noise reduction of 3 EPNdB at the flyover and sideline monitoring stations, were 110.3 EPNdB (sideline noise), 113.1 EPNdB (centerline noise) and 110.5 EPNdB (approach noise)
Shock and statistical acceleration of energetic particles in the interplanetary medium
Definite evidence for particle acceleration in the solar wind came around a decade ago. Two likely sources are known to exist: particles may be accelerated by the turbulence resulting from the superposition of Alfven and Magnetosonic waves (Statistical Acceleration) or they may be accelerated directly at shock fronts formed by the interaction of fast and slow solar wind (CIR's) or by traveling shocks due to sporadic coronal mass ejections. Naurally both mechanisms may be operative. In this work the acceleration problem was tackled numerically using Helios 1 and 2 data to create a realistic representation of the Heliospheric plasma. Two 24 hour samples were used: one where there are only wave like fluctuations of the field (Day 90 Helios 1) and another with a shock present in it (Day 92 of Helios 2) both in 1976 during the STIP 2 interval. Transport coefficients in energy space have been calculated for particles injected in each sample and the effect of the shock studied in detail
A magnetic thrust action on small bodies orbiting a pulsar
We investigate the electromagnetic interaction of a relativistic stellar wind
with small bodies in orbit around the star. Based on our work on the theory of
Alfv\'en wings to relativistic winds presented in a companion paper, we
estimate the force exerted by the associated current system on orbiting bodies
and evaluate the resulting orbital drift. This Alfv\'enic structure is found to
have no significant influence on planets or smaller bodies orbiting a
millisecond pulsar. %influence on the orbit of bodies around a millisecond
pulsar. On the timescale of millions of years, it can however affect the orbit
of bodies with a diameter of 100 kilometres around standard pulsars with a
period 1 s and a magnetic field T. Kilometer-sized
bodies experience drastic orbital changes on a timescale of years.Comment: accepted for publication in "Astronomy and Astrophysics
Simulator study of the low-speed handling qualities of a supersonic cruise arrow-wing transport configuration during approach and landing
A fixed-based simulator study was conducted to determine the low-speed flight characteristics of an advanced supersonic cruise transport having an arrow wing, a horizontal tail, and four dry turbojets with variable geometry turbines. The primary piloting task was the approach and landing. The statically unstable (longitudinally) subject configuration has unacceptable low-speed handling qualities with no augmentation. Therefore, a hardened stability augmentation system is required to achieve acceptable handling qualities, should the normal operational stability and control augmentation system fail. In order to achieve satisfactory handling qualities, considerable augmentation was required
Ribose supplementation alone or with elevated creatine does not preserve high energy nucleotides or cardiac function in the failing mouse heart
Background: Reduced levels of creatine and total adenine nucleotides (sum of ATP, ADP and AMP) are hallmarks of chronic
heart failure and restoring these pools is predicted to be beneficial by maintaining the diseased heart in a more favourable
energy state. Ribose supplementation is thought to support both salvage and re-synthesis of adenine nucleotides by
bypassing the rate-limiting step. We therefore tested whether ribose would be beneficial in chronic heart failure in control
mice and in mice with elevated myocardial creatine due to overexpression of the creatine transporter (CrT-OE).
Methods and Results: Four groups were studied: sham; myocardial infarction (MI); MI+ribose; MI+CrT-OE+ribose. In a pilot
study, ribose given in drinking water was bioavailable, resulting in a two-fold increase in myocardial ribose-5-phosphate
levels. However, 8 weeks post-surgery, total adenine nucleotide (TAN) pool was decreased to a similar amount (8–14%) in all
infarcted groups irrespective of the treatment received. All infarcted groups also presented with a similar and substantial
degree of left ventricular (LV) dysfunction (3-fold reduction in ejection fraction) and LV hypertrophy (32–47% increased
mass). Ejection fraction closely correlated with infarct size independently of treatment (r2 = 0.63, p<0.0001), but did not
correlate with myocardial creatine or TAN levels.
Conclusion: Elevating myocardial ribose and creatine levels failed to maintain TAN pool or improve post-infarction LV
remodeling and function. This suggests that ribose is not rate-limiting for purine nucleotide biosynthesis in the chronically
failing mouse heart and that alternative strategies to preserve TAN pool should be investigated
Myocardial creatine levels do not influence response to acute oxidative stress in isolated perfused heart
Background: Multiple studies suggest creatine mediates anti-oxidant activity in addition to its established role in cellular
energy metabolism. The functional significance for the heart has yet to be established, but antioxidant activity could
contribute to the cardioprotective effect of creatine in ischaemia/reperfusion injury.
Objectives: To determine whether intracellular creatine levels influence responses to acute reactive oxygen species (ROS)
exposure in the intact beating heart. We hypothesised that mice with elevated creatine due to over-expression of the
creatine transporter (CrT-OE) would be relatively protected, while mice with creatine-deficiency (GAMT KO) would fare
worse.
Methods and Results: CrT-OE mice were pre-selected for creatine levels 20–100% above wild-type using in vivo 1
H–
MRS.
Hearts were perfused in isovolumic Langendorff mode and cardiac function monitored throughout. After 20 min
equilibration, hearts were perfused with either H2O2 0.5 mM (30 min), or the anti-neoplastic drug doxorubicin 15 mM
(100 min). Protein carbonylation, creatine kinase isoenzyme activities and phospho-PKCd expression were quantified in
perfused hearts as markers of oxidative damage and apoptotic signalling. Wild-type hearts responded to ROS challenge
with a profound decline in contractile function that was ameliorated by co-administration of catalase or dexrazoxane as
positive controls. In contrast, the functional deterioration in CrT-OE and GAMT KO hearts was indistinguishable from wildtype
controls, as was the extent of oxidative damage and apoptosis. Exogenous creatine supplementation also failed to
protect hearts from doxorubicin-induced dysfunction.
Conclusions: Intracellular creatine levels do not influence the response to acute ROS challenge in the intact beating heart,
arguing against creatine exerting (patho-)physiologically relevant anti-oxidant activity
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