845 research outputs found
Paying tribute to James Eells and Joseph H. Sampson: In commemoration of the 50th anniversary of their pioneering work on harmonic maps
Characterization of a high-resolution breath acetone meter for ketosis monitoring
Background: The ketone bodies beta-hydroxybutyrate (BHB) and acetone are endogenous products of fatty acid metabolism. Although ketone levels can be monitored by measuring either blood BHB or breath acetone, determining the precise correlation between these two measurement methods has been challenging. The purpose of this study is to characterize the performance of a novel portable breath acetone meter (PBAM) developed by Readout, Inc., to compare single versus multiple daily ketone measurements, and to compare breath acetone (BrAce) and blood BHB measurements.
Methods: We conducted a 14-day prospective observational cohort study of 21 subjects attempting to follow either a low-carbohydrate/ketogenic or a standard diet. Subjects were asked to concurrently measure both blood BHB and BrAce five times per day and report the results using an online data entry system. We evaluated the utility of multiple daily measurements by calculating the coefficient of variation (CV) for each daily group of measurements. We calculated the correlation between coincident BrAce and blood BHB measurements using linear ordinary least squares regression analysis. We assessed the ability of the BrAce measurement to accurately predict blood BHB states using receiver operating characteristic (ROC) analysis. Finally, we calculated a daily ketone exposure (DKE) using the area under the curve (AUC) of a ketone concentration versus time graph and compared the DKE of BrAce and blood BHB using linear ordinary least squares regression.
Results: BrAce and blood BHB varied throughout the day by an average of 44% and 46%, respectively. The BrAce measurement accurately predicted whether blood BHB was greater than or less than the following thresholds: 0.3 mM (AUC = 0.898), 0.5 mM (AUC = 0.854), 1.0 mM (AUC = 0.887), and 1.5 mM (AUC = 0.935). Coincident BrAce and blood BHB measurements were moderately correlated with
Conclusions: The results validated the performance of the PBAM. The BrAce/BHB correlation was similar to literature values where BrAce was measured using highly accurate lab instruments. Additionally, BrAce measurements using the PBAM can be used to predict blood BHB states. The relatively high daily variability of ketone levels indicate that single blood or breath ketone measurements are often not sufficient to assess daily ketone exposure for most users. Finally, although single coincident blood and breath ketone measurements show only a moderate correlation, possibly due to the temporal lag between BrAce and blood BHB, daily ketone exposures for blood and breath are highly correlated
Tipificación en Gutierrezia (Asteraceae, Astereae)
During the course of the revision of the South American species of Gutierrezia, we have detected names that require typification. After the analysis of the protologues and the herbarium specimens, we designated eight lectotypes and one neotype for nine names of the Gutierrezia genus and we assigned the category of holotype to one specimen. A detailed discussion is provided for each case.Durante el transcurso de la revisión de las especies sudamericanas de Gutierrezia, hemos podido hallar nombres que requieren tipificación. Luego del análisis de los protologos y especímenes de herbario, hemos designado ocho lectótipos y un neótipo para nueve nombres del género Gutierrezia. Además, se asignó la categoría de hólotipo a un especimen. Se provee una discusión detallada para cada nombre
An Educational Module: Enhancing Provider Awareness of a Mentorship Program for Student Registered Nurse Anesthetist to Enhance Success and Reduce Stress
Student registered nurse anesthetists experience high stress levels as they transition from experts in the Intensive Care Unit to novice anesthesia providers in nurse anesthesia school. With the high-stress levels experienced by Student registered nurse anesthetists (SRNA) due to the high demands of clinical performance and academic rigor, success is often impeded. A literature review was conducted to investigate stressors nurse anesthesia students perceive, formal mentorship programs for anesthesia residencies, and how their implementations enhance success in both didactic and clinical education.An alumni list from a public research University in South Florida that has a nurse anesthesia program that educated critical care nurses in nurse anesthesiology. Anesthesia providers were educated on the benefits of mentorship to help reduce stress and enhance success in nurse anesthesiology programs. A pretest was disseminated to participants to assess anesthesia provider knowledge and beliefs regarding the importance of mentorship programs in nurse anesthesia programs. An educational module was provided to educate on the stressors SRNAs experience as they progress thru the program in both clinical and didactic, the coping mechanisms employed to mitigate the stress, and the literature finding relevant to this educational module. After the presentation, a post test survey was given to the participants to assess the knowledge gained. After implementing the educational module, there was an increase in knowledge and attitudes regarding mentorship in nurse anesthesia programs. Participants concur with the data from the literature, that mentorship programs in nurse anesthesia education reduce stress and enhance success. Findings show that establishing formal mentorship programs enhanced success and reduced stress compared with anesthesia providers without access to mentorship. Formal mentorship training increases satisfaction and comfort for the stakeholders involved. It was found that providers mentored developed features such as active decision-making skills and independence. Additionally, life-changing stressors could affect clinical and academic performance. Behaviors of mistreatment experienced by SRNAs, learning styles, and values deemed necessary by providers in training. Barriers and challenges in mentoring and the need to establish clear objectives, preparation, and training for mentorship to be logistically implemented. Transitioning from SRNA to Certified Registered Nurse Anesthetist (CRNA) can be challenging. SRNAs experience fluctuating levels of stress during the completion of their training. Pursuing graduate-level anesthesia education requires a support system, life adjustments, and full-time commitment. The novice anesthesia student experiences high levels of vulnerability, and a third party, such as a support group or mentor, often reinforces self-confidence. Mentorship is a process through which an individual guides another in developing the professional skills and knowledge necessary for professional development. Future research to formally incorporate a professional development mentorship course into nurse anesthesia curriculums to standardize a peer to peer mentoring program, using a committee that includes key stakeholders such as CRNAs, SRNAs, faculty, and program directors to establish standard operating procedures and bylaws to enhance its implementation in nurse anesthesia programs
Externally excited traveling pulses in a neon glow discharge.
http://www.archive.org/details/externallyexcite00rattU.S. Navy (U.S.N.) author
Oxygen-resistant [FeFe]hydrogenases: new biocatalysis tools for clean energy and cascade reactions
La gran erupción de hace 4.2 ka cal en Cerro Blanco, Zona Volcánica Central, Andes: nuevos datos sobre los depósitos eruptivos holocenos en la Puna sur y regiones adyacentes
The eruption of the Cerro Blanco Volcanic Complex, in the southern Puna, NW Argentina dated at 4410–4150 a cal BP, was investigated to produce new information on stratigraphy, geomorphology, physical volcanology, radiocarbon dating, petrography, and geochemistry. Identification of pre–, syn–, and post–caldera products allowed us to estimate the distribution of the Plinian fallout during the paroxysmal syn–caldera phase of the eruption. The new results provide evidence for a major rhyolitic explosive eruption that spread volcanic deposits over an area of ~500,000 km2, accumulating > 100 km3 of tephra (bulk volume). This last value exceeds the lower threshold of Volcanic Explosive Index (VEI) of 7. Ash-fall deposits mantled the region at distances > 400 km from source and thick pyroclastic-flow deposits filled neighbouring valleys up to 35 km away. This eruption is the largest documented during the past five millennia in the Central Volcanic Zone of the Andes, and is probably one of the largest Holocene explosive eruptions in the world. We have also identified two additional rhyolitic eruptions in the region from two other eruptive sources: one during the Early–Holocene and another in the Late–Holocene. The identification and characterisation of these significant volcanic events provide new constraints into regional Holocene geological and archaeological records, and offer extensive regional chronostratigraphic markers over a wide geographical area of South America.La erupción del Complejo Volcánico Cerro Blanco en el sur de la Puna, noroeste de Argentina (4410–4150 a BP) se investigó para obtener nueva información sobre estratigrafía, geomorfología, volcanología física, dataciones por radiocarbono, petrografía y geoquímica. La caracterización de los productos en relación a la evolución de la caldera de Cerro Blanco permitió estimar la distribución de los depósitos de ceniza de la fase paroxísmica Plineana de la erupción. Estos novedosos resultados evidencian una gran erupción explosiva riolítica que generó depósitos cineríticos en un área de aproximadamente 500.000 km2, acumulando > 100 km3 de tefra (volumen total). Este último valor supera el umbral inferior del Índice de Explosividad Volcánica (IEV) de 7. Los depósitos de caída de ceniza cubrieron la región, llegando a más de 400 km desde el Complejo Volcánico de Cerro Blanco, y los potentes depósitos de flujos piroclásticos rellenaron los valles vecinos alcanzando una distancia de 35 km. Esta erupción es la más grande documentada durante los últimos cinco milenios en la Zona Volcánica Central de los Andes y es probablemente una de las mayores erupciones explosivas holocenas del mundo. Además, se han identificado otras dos erupciones riolíticas en la región procedentes de otros dos centros eruptivos: una durante el Holoceno temprano y otra en el Holoceno tardío. La identificación y caracterización de estos grandes eventos volcánicos proporcionan nuevas guías para los registros geológicos y arqueológicos regionales del Holoceno, siendo marcadores cronostratigráficos de aplicación a una extensa área geográfica de América del Sur
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Localized functionalization of single nanopores
We demonstrate the localization of chemical functionality at the entrance of single nanopores for the first time by using the controlled growth of an oxide ring. Nanopores were fabricated by Focused Ion Beam machining on silicon platforms, locally derivatized by ion beam assisted oxide deposition, and further functionalized with DNA probes via silane chemistry. Ionic current recorded through single nanopores at various stages of the fabrication process demonstrated that the apertures can be locally functionalized with DNA probes. Future applications for this functional platform include the selective detection of biological organisms and molecules by ionic current blockade measurements
Acute stress impairs sensorimotor gating via the neurosteroid allopregnanolone in the prefrontal cortex
Ample evidence indicates that environmental stress impairs information processing, yet the underlying mechanisms remain partially elusive. We showed that, in several rodent models of psychopathology, the neurosteroid allopregnanolone (AP) reduces the prepulse inhibition (PPI) of the startle, a well-validated index of sensorimotor gating. Since this GABAA receptor activator is synthesized in response to acute stress, we hypothesized its participation in stress-induced PPI deficits. Systemic AP administration reduced PPI in C57BL/6J mice and Long-Evans, but not Sprague-Dawley rats. These effects were reversed by isoallopregnanolone (isoAP), an endogenous AP antagonist, and the GABAA receptor antagonist bicuculline and mimicked by AP infusions in the medial prefrontal cortex (mPFC). Building on these findings, we tested AP's implication in the PPI deficits produced by several complementary regimens of acute and short-term stress (footshock, restraint, predator exposure, and sleep deprivation). PPI was reduced by acute footshock, sleep deprivation as well as the combination of restraint and predator exposure in a time- and intensity-dependent fashion. Acute stress increased AP concentrations in the mPFC, and its detrimental effects on PPI were countered by systemic and intra-mPFC administration of isoAP. These results collectively indicate that acute stress impairs PPI by increasing AP content in the mPFC. The confirmation of these mechanisms across distinct animal models and several acute stressors strongly supports the translational value of these findings and warrants future research on the role of AP in information processing
Fiscal policy, banks and the financial crisis
This paper studies the effectiveness of Euro Area (EA) fiscal policy, during the recent financial crisis, using an estimated New Keynesian model with a bank. A key dimension of policy in the crisis was massive government support for banks-that dimension has so far received little attention in the macro literature. We use the estimated model to analyze the effects of bank asset losses, of government support for banks, and other fiscal stimulus measures, in the EA. Our results suggest that support for banks had a stabilizing effect on EA output, consumption and investment. Increased government purchases helped to stabilize output, but crowded out consumption. Higher transfers to households had a positive impact on private consumption, but a negligible effect on output and investment. Banking shocks and increased government spending explain half of the rise in the public debt/GDP ratio since the onset of the crisis
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