3,101 research outputs found
Ultraviolet Three Axis Attitude Sensor
It is becoming increasingly obvious that satellite bus technologies, which have been developed for traditional larger satellite platforms, are not always suitable for use with smallsats. This is due to the intrinsic limitations in size, weight, available power, and cost associated with the latter. The problem is particularly obvious for attitude reference sensors of both the earth and star viewing type. In response to the lack of suitable sensors for this purpose, Honeywell is developing a system that determines three axis attitude through ultraviolet imaging of the earth\u27s limb and adjacent stars. A non-conventional wide angle optics assembly and intensified CCD array are utilized for this purpose. Because of the intrinsic stability of the features being observed and the large number of pixels on which the scene is imaged, it should be possible to obtain accuracies on the order of .05 degrees with a very small and lightweight sensor configuration
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Open Clusters as Laboratories for Stellar Spin Down and Magnetic Activity Decay
The oldest open clusters within 250 pc of the Sun, the Hyades and Praesepe, are important benchmarks for calibrating stellar properties such as rotation and magnetic activity. As they have the same age and roughly solar metallicity, these clusters serve as an ideal laboratory for testing the agreement between theoretical and empirical rotation-activity relations at ~650 Myr. The re-purposed Kepler mission, K2, has allowed me to measure rotation periods for dozens of Hyads and hundreds of Praesepe members, including the first periods measured for fully convective Hyads. These data have enabled new tests of models describing the evolution of stellar rotation; discrepancies with these models imply that we still do not fully understand how magnetic fields affect stellar spin-down. I show how we can compare the dependence of H-alpha and X-ray emission on rotation in order to test theories of magnetic field topology and stellar dynamos. These tests inform models of stellar wind-driven angular momentum loss and the age-rotation-activity relation. I also present rotation periods measured for 48 Hyads and 677 Praesepe members with K2, and discuss the impact of unresolved binaries on the study of rotational evolution
Large Neutral Amino Acid Status in Association with P:T Ratio and Diet in Adult and Pediatric Patients with Phenylketonuria
Background
Intake of large neutral amino acids (LNAA) may inhibit phenylalanine (PHE) transport across the blood brain barrier and assist with blood PHE control in patients with phenylketonuria (PKU). We evaluated the interrelationship between LNAA in plasma and diet on Phe:Tyr (P:T) ratio in patients with PKU and the influence of dietary factors on plasma LNAA markers. Methods
Plasma amino acid values and 3‐day food record analysis from two studies (34 male/30 female; age 4.6‐47 years) were examined. For pediatrics (years) and adults (≥18 years) the relationship between P:T ratio, plasma LNAA, and dietary intake patterns were investigated. Results
Dietary factors influencing P:T ratio included intake of total protein (g/kg), medical food (MF) protein (g/kg, % below Rx), and LNAA (g) in the full cohort (P \u3c .05). Associations were found between plasma valine and other dietary and plasma LNAA in pediatrics (P \u3c .05) and plasma LNAA with dietary LNAA intake in adults (P = .019). Plasma P:T ratio was inversely associated with plasma LNAA concentrations in both age groups (P \u3c .05). Aside from histidine in pediatrics (P = .024), plasma LNAA did not differ by having plasma PHE levels within or above the therapeutic range (120‐360 μmol/L). Plasma LNAA in both age groups was similar to reported healthy control values. Conclusion
P:T ratio is significantly tied to dietary LNAA, adherence to MF Rx, and plasma LNAA concentrations. Additionally, P:T ratio and valine may be effective clinical proxies for determining LNAA metabolic balance and LNAA quality of the diet in patients with PKU
Sorption Properties of Greenwaste Biochar for Two Triazine Pesticides
This work by ISTC’s Wei Zheng and Kishore Rajagopalan and collaborators from Delaware State University provides innovative solutions for producing energy and food in a sustainable environment. Renewable energy can be produced by converting greenwaste such as using highway grass clippings for gasoline or biodiesel through a process called pyrolysis (heating to 450°C with limited oxygen) and then implementing some refining techniques. However, the pyrolysis process produces a byproduct called biochar, which is a carbon-rich substance similar to activated carbon. The biochar byproduct could be landfilled, but the researchers have a better idea.The other aspect of this research is determining how to produce food without contaminating the environment. The researchers considered two common pesticides. Atrazine and simazine are used as broad-spectrum pesticides/herbicides for agricultural, recreational, and residential uses, but the most common use is for field crop applications. These pesticides can inadvertently contaminate water ways and water bodies from rain events and soil erosion. To prevent this contamination, the researchers proposed mixing biochar into the soil to prevent pesticide/herbicide loss from the field. Full results published in Zheng, Wei, et al (2010). "Sorption properties of greenwaste biochar for two triazine pesticides." Journal of Hazardous Materials 181(1-3), 121-126. https://doi.org/10.1016/j.jhazmat.2010.04.103Ope
Strontium isotope stratigraphy and age estimates for the Leisey Shell Pit faunas, Hillsborough County, Florida
The vertebrate fauna of the Leisey Shell Pit near Tampa Bay, Florida, represents one of the more significant lrvingtonian mammalian faunas of North America. The fossil vertebrates occur in thin bone beds bounded above and below by massive shell beds containing a rich invertebrate ( chiefly molluscan) fauna. Debate has arisen concerning the precise age of the faunas at Leisey. Although generally agreed to be Pleistocene, estimates based upon vertebrate biostratigraphy suggest a somewhat older age than do estimates based upon molluscan biostratigraphy. To help resolve this controvefliy, 87Sr/86Sr ratios were determined on molluscan shells throughout the section. These ratios were then correlated to the global sea water 87Sr/86Sr curve for age detennination. The Sr isotopes support an early Pleistocene age for the vertebrate fauna and suggest a complex history for the shell accumulations
Principios lingüísticos que influyen en la enseñanza del inglés en la carrera de medicina
EL Proceso de enseñanza aprendizaje de la asignatura inglés en Ciencias Médicas se desarrolla bajo la premisa de crear profesionales de la salud capaces de comunicarse en esta lengua extranjera. Los principios lingüísticos, permiten al profesor de idiomas propiciar las vías para que el alumno se convierta en activo protagonista del proceso docente-educativo. En la enseñanza del inglés con fines específicos el educando debe lidiar con un vocabulario que solo puede ser adquirido con situaciones comunicativas propias de la carrera de medicina y el enfoque comunicativo que debe estar presente en las diferentes etapas de la clase, favorece la expresión oral en los estudiantes; uno de los medios para lograr que el estudiante se integre de manera activa y consciente en el descubrimiento y adquisición de lo nuevo, lo constituye la buena preparación lingüística del profesor
Gearing up for Improved Collaboration:the Potentials and Limits of Cooperative Research for Incorporating Fishermen's Knowledge
The Effect of Intact Protein from Foods and Phenylalanine Free Medical Foods on Large Neutral Amino Acids in Patients with Phenylketonuria.
Objective: The primary aim of this retrospective cohort study was to determine the association between the source of dietary protein intake and the sum of plasma concentration of large neutral amino acids (LNAA) in patients with Phenylketonuria (PKU). A secondary aim of the study was to examine the effect of dietary compliance on plasma concentration of LNAA. Methods: The analysis included combined participant data from two previous studies conducted at the Emory University School of Medicine. Subjects are males (n=34) and females (n=43) with PKU ages 4-50 years. A Student t-test was used to compare total combined plasma LNAA (excluding tryptophan and phenylalanine) by dietary compliance status (alpha=0.05). Correlation statistics were used to determine the association between the ratio of reported intact food protein to medical food protein on plasma levels of LNAA. Multiple regression analysis was used to examine the contribution of intact protein to medical food protein ratio and other variables to plasma LNAA. Results: The median ratio of intact protein to medical food protein reported was 0.354 (IQR: 0.188, 0.914). Median percent of PHE intake over the PHE intake recommendation was 31.64 (Interquartile range [IQR]; 7.44, 104.98). Plasma concentration of LNAA did not differ significantly between those with plasma PHE levels within the therapeutic range μmol/L (compliant; 611.7 μmol/L [n=19]) vs levels above the therapeutic range (non-compliant; 595.3 μmol/L [n=47]); p=0.613). There was an inverse marginal correlation between the ratio of intact protein to medical food protein and plasma concentration of LNAA for those who were compliant (r = -0.436, r = 0.1) although the association was not statistically significant (p=0.08). No correlation was found for patients who were non-compliant. Regression analysis revealed that plasma concentration of LNAA was not significantly affected by the ratio of intact protein to medical food protein ratio, age, or gender. Conclusions: Although not statistically significant, a negative trend was observed between plasma LNAA concentration and the intact protein to medical food protein ratio in patients compliant with the PHE prescription. This suggests that the ratio of intact dietary protein to protein coming from medical food, as reported by patient diet records, may promote increased plasma LNAA levels in the effective treatment of PKU. The majority of the sample (74%) were non-compliant with diet based on plasma PHE levels. Future studies are needed to determine the consequences of non-compliance by decreased intake of medical food protein or increased intake of intact protein on plasma LNAA concentration and downstream health effects
Disaster Vulnerability
Vulnerability drives disaster law, yet the literature lacks both an overarching analysis of the different aspects of vulnerability and a nuanced examination of the factors that shape disaster outcomes. Though central to disaster law and policy, vulnerability often lurks in the shadows of a disaster, evident only once the worst is past and the bodies have been counted. The COVID-19 pandemic is a notable exception to this historical pattern: from the beginning of the pandemic, it has been clear that the virus poses different risks to different people, depending on vulnerability variables. This most recent pandemic experience thus provides a useful vantage point for analyzing vulnerability. Drawing on empirical data from the pandemic and experiences from past disasters, this Article identifies and discusses the policy implications of three dimensions of disaster vulnerability: the geography of vulnerability, competing or conflicting vulnerabilities, and political vulnerability. First, it explores the geography of vulnerability, using statistical analysis and geographic information system (GIS) mapping. The Article presents an innovative COVID-19 vulnerability index that identifies the country’s most vulnerable counties and the leading driver of vulnerability for each county. It demonstrates how this index could have informed voter accommodations during the 2020 elections and mask mandates throughout the pandemic.
The Article also shows how, going forward, similar modeling could make disaster management more proactive and better able to anticipate needs and prioritize disaster mitigation and response resources. Second, this Article explores competing or conflicting vulnerabilities––situations where policy-makers must prioritize one vulnerable group or one aspect of vulnerability over another. To illustrate this, it considers two other policy challenges: school closures and vaccine distribution.
Finally, the Article explores political vulnerability, analyzing how disasters make already-vulnerable groups even more vulnerable to certain harms, including political neglect, stigmatization, disenfranchisement, and displacement. In sum, this Article draws upon the costly lessons of COVID-19 to suggest a more robust framework for policy-makers to assess and respond to vulnerability in future disaster
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