Habitats and Spider Prey of \u3ci\u3eDipogon Sayi Sayi\u3c/i\u3e (Hymenoptera: Pompilidae) in Washington County, Maine

Spider wasps were reared from three types of trap-nests deployed in strip-clearcut areas of a spruce-fir-mixed hardwood forest of Maine. Collections of Dipogon sayi sayi from Mooseborn National Wildlife Refuge, Washington County, represent the easternmost records for the United States. Spider prey included females of Misumena vatia, Xysticus emertoni (new prey record), and X. punctatus, and juveniles and penultimate males of Xysticus sp. We found no evidence of nest-site competition between spider wasps and eumenid wasps (Hymenoptera: Eumenidae) that prey on spruce budwornl, Choristoneura fumiferana, when available nesting sites ranged from 320 to 4400

Dimensionless Measures of Turbulent Magnetohydrodynamic Dissipation Rates

The magnetic Reynolds number R_M, is defined as the product of a characteristic scale and associated flow speed divided by the microphysical magnetic diffusivity. For laminar flows, R_M also approximates the ratio of advective to dissipative terms in the total magnetic energy equation, but for turbulent flows this latter ratio depends on the energy spectra and approaches unity in a steady state. To generalize for flows of arbitrary spectra we define an effective magnetic dissipation number, R_{M,e}, as the ratio of the advection to microphysical dissipation terms in the total magnetic energy equation, incorporating the full spectrum of scales, arbitrary magnetic Prandtl numbers, and distinct pairs of inner and outer scales for magnetic and kinetic spectra. As expected, for a substantial parameter range R_{M,e}\sim {O}(1) << R_M. We also distinguish R_{M,e} from {\tilde R}_{M,e} where the latter is an effective magnetic Reynolds number for the mean magnetic field equation when a turbulent diffusivity is explicitly imposed as a closure. That R_{M,e} and {\tilde R}_{M,e} approach unity even if R_M>>1 highlights that, just as in hydrodynamic turbulence,energy dissipation of large scale structures in turbulent flows via a cascade can be much faster than the dissipation of large scale structures in laminar flows. This illustrates that the rate of energy dissipation by magnetic reconnection is much faster in turbulent flows, and much less sensitive to microphysical reconnection rates compared to laminar flows.Comment: 14 pages (including 2 figs), accepted by MNRA

Measuring and Correcting Wind-Induced Pointing Errors of the Green Bank Telescope Using an Optical Quadrant Detector

Wind-induced pointing errors are a serious concern for large-aperture high-frequency radio telescopes. In this paper, we describe the implementation of an optical quadrant detector instrument that can detect and provide a correction signal for wind-induced pointing errors on the 100m diameter Green Bank Telescope (GBT). The instrument was calibrated using a combination of astronomical measurements and metrology. We find that the main wind-induced pointing errors on time scales of minutes are caused by the feedarm being blown along the direction of the wind vector. We also find that wind-induced structural excitation is virtually non-existent. We have implemented offline software to apply pointing corrections to the data from imaging instruments such as the MUSTANG 3.3 mm bolometer array, which can recover ~70% of sensitivity lost due to wind-induced pointing errors. We have also performed preliminary tests that show great promise for correcting these pointing errors in real-time using the telescope's subreflector servo system in combination with the quadrant detector signal.Comment: 17 pages, 11 figures; accepted for publication in PAS

RELACIÓN ENTRE EL RENDIMIENTO ACADÉMICO DE LOS INGRESANTES Y EL ABANDONO DE LOS ESTUDIOS UNIVERSITARIOS: COMPARACIÓN ENTRE CARRERAS DE INGENIERÍA Y ECONOMICAS

La preocupación por orientar adecuadamente los recursos que se afectan a los programas de apoyo a los estudiantes de primer año de las carreras, nos llevó a trabajar intentando generar un modelo que sea capaz de determinar, anticipadamente, que estudiantes se encontrarían en situación de abandonar sus estudios. En una primera aplicación del modelo, se analizó la correlación entre el rendimiento académico y el abandono para diez cohortes de ingresantes, de las dos carreras de Ingeniería que ofrece la Universidad Nacional de Luján, observándose una significativa correlación entre el rendimiento académico del estudiante en el primer cuatrimestre y el abandono de los estudios durante el segundo, tercero y cuarto cuatrimestre. En este trabajo, presentamos los resultados que se alcanzaron al aplicar el mismo modelo a las diez cohortes, equivalentes, de estudiantes de las dos carreras del campo de las Ciencias Económicas que se ofrecen en la misma Institución: Licenciatura en Administración y Licenciatura en Comercio Internacional. Las principales conclusiones a las que arribamos es que el modelo se valida positivamente al cambiar el origen disciplinar de las carreras en las que se aplica. Por otra parte, existe mayor correlación entre el rendimiento académico en el primer cuatrimestre y el momento en que se abandonan los estudios para los estudiantes de carreras de Ciencias Económicas que la observada en los de Ingeniería. Se repite el fenómeno observado para las carreras de Ingeniería, de disminuir la correlación entre el rendimiento académico y el abandono para la cohorte 2002. También se detecta una diferencia significativa respecto de la moda para la cantidad de asignaturas aprobadas durante el primer cuatrimestre para las cuatro carreras

SERCA pump activity is physiologically regulated by presenilin and regulates amyloid β production

In addition to disrupting the regulated intramembraneous proteolysis of key substrates, mutations in the presenilins also alter calcium homeostasis, but the mechanism linking presenilins and calcium regulation is unresolved. At rest, cytosolic Ca2+ is maintained at low levels by pumping Ca2+ into stores in the endoplasmic reticulum (ER) via the sarco ER Ca2+-ATPase (SERCA) pumps. We show that SERCA activity is diminished in fibroblasts lacking both PS1 and PS2 genes, despite elevated SERCA2b steady-state levels, and we show that presenilins and SERCA physically interact. Enhancing presenilin levels in Xenopus laevis oocytes accelerates clearance of cytosolic Ca2+, whereas higher levels of SERCA2b phenocopy PS1 overexpression, accelerating Ca2+ clearance and exaggerating inositol 1,4,5-trisphosphate–mediated Ca2+ liberation. The critical role that SERCA2b plays in the pathogenesis of Alzheimer's disease is underscored by our findings that modulating SERCA activity alters amyloid β production. Our results point to a physiological role for the presenilins in Ca2+ signaling via regulation of the SERCA pump

Non-invasive assessment of endothelial function in children with obesity and lipid disorders

BACKGROUND: Digital tonometry is designed to non-invasively screen for endothelial dysfunction by the detection of impaired flow-induced reactive hyperaemia in the fingertip. We determined whether digital reactive hyperaemia correlated with risk factors for atherosclerosis in two groups of children at increased risk for endothelial dysfunction. METHODS: A total of 15 obese children and 23 non-obese, dyslipidaemic children, 8-21 years of age, were enrolled, and their medical histories, anthropometric measurements, carotid wall thickness by means of ultrasonography, and fasting blood samples for cardiovascular risk factors were obtained. The standard endoPAT index of digital reactive hyperaemia was modified to reflect the true peak response or the integrated response of the entire post-occlusion period. In each group, age, sex, pubertal status, carotid wall thickness, and multiple cardiovascular risk factors were tested as predictors of endothelial dysfunction. RESULTS: In the non-obese, dyslipidaemic group, but not in the obese group, both indices strongly correlated with height (r=0.55, p=0.007, by peak response) followed by weight, waist circumference, and age. In both groups, neither index of reactive hyperaemia significantly correlated with any other cardiovascular risk factor. CONCLUSIONS: Contrary to the known age-related increase in atherosclerosis, digital reactive hyperaemia increased with age and its correlates in non-obese, dyslipidaemic children and was not related to other cardiovascular risk factors in either group. The reason for the lack of this relationship with age in obese children is unknown. The age-dependent physiology of digital microvascular reactivity and the endothelium-independent factors controlling the peak hyperaemic response need further study in children with a wide age range

Synthesis of the elements in stars: forty years of progress

Forty years ago Burbidge, Burbidge, Fowler, and Hoyle combined what we would now call fragmentary evidence from nuclear physics, stellar evolution and the abundances of elements and isotopes in the solar system as well as a few stars into a synthesis of remarkable ingenuity. Their review provided a foundation for forty years of research in all of the aspects of low energy nuclear experiments and theory, stellar modeling over a wide range of mass and composition, and abundance studies of many hundreds of stars, many of which have shown distinct evidence of the processes suggested by B2FH. In this review we summarize progress in each of these fields with emphasis on the most recent developments

Swing-Free Cranes via Input Shaping of Operator Commands

This paper presents an open-loop control method for suppressing payload oscillation or swing caused by operator commanded maneuvers in rotary boom cranes and the method is experimentally verified on a one-sixteenth scale model of a Hagglunds shipboard crane. The crane configuration consists of a payload mass that swings like a spherical pendulum on the end of a lift-line which is attached to a boom capable of hub rotation (slewing) and elevation (luffing). Positioning of the payload is accomplished through the hub and boom angles and the load-line length. Since the configuration of the crane affects the excitation and response of the payload, the swing control scheme must account for the varying geometry of the system. Adaptive forward path command filters are employed to remove components of the command signal which induce payload swing