CO line emission from clumpy molecular clouds : the case of Orion.

AstronomyDoctor of Philosophy (PhD

Moisture, a Vital but Neglected Factor in the Seasonal Ecology of Insects: Hypotheses and Tests of Mechanisms

Of the major physical factors that influence insect seasonal ecology, moisture is least understood and least appreciated. It is our premise that experimental probing of insects from diverse zones and various habitats would reveal general patterns of insect responses to moisture that are as striking as those for photoperiod and temperature. Using the paradigms of photoperiod and temperature as ecophysiological determinants of insect seasonality, we hypothesize that moisture influences insect life cycles via one or more of three mechanisms—as a token stimulus for diapause, modulator of developmental or reproductive rates, or behavioral cue for vital seasonal events. For heuristic purposes, we offer each of these hypotheses in close association with approaches for testing their validity in insects that undergo dry-season dormancy. The approaches appear appropriate for examining the role of moisture in the life histories of terrestrial invertebrates other than insects, as well as plants and microbes that have a seasonal resting stage. Elucidating moisture's role in insect seasonal cycles is critical to the development of comprehensive phenological models, improved insect management systems, and identification of novel evolutionary mechanisms for adaptation to wet-dry seasons, especially in tropical, subtropical, and Mediterranean region

Dust Polarization From Starlight Data

We present a statistical analysis of the interstellar medium (ISM) polarization from the largest compilation available of starlight data, which comprises ~ 5500 stars. The measured correlation between the mean polarization degree and extinction indicates that ISM dust grains are not fully aligned with the uniform component of the large-scale Galactic magnetic field. Moreover, we estimate the ratio of the uniform to the random plane-of-the-sky components of the magnetic field to be B_u/B_r = 0.8. From the analysis of starlight polarization degree and position angle we find that the magnetic field broadly follows Galactic structures on large-scales. On the other hand, the angular power spectrum C_l of the polarization degree for Galactic plane data is found to be consistent with a power-law, C_l ~ l^{-1.5} (where l = 180 deg/\theta is the multipole order), for angular scales \theta > 10 arcmin. We argue that this data set can be used to estimate diffuse polarized emission at microwave frequencies.Comment: 7 pages, 7 figures. To appear in proc. of the AIP conf. ``Astrophysical Polarized Backgrounds'', eds. S. Cecchini, S. Cortiglioni, R. Sault and C. Sbarr

Statistical Properties of Galactic Starlight Polarization

We present a statistical analysis of Galactic interstellar polarization from the largest compilation available of starlight data. The data comprises ~ 9300 stars of which we have selected ~ 5500 for our analysis. We find a nearly linear growth of mean polarization degree with extinction. The amplitude of this correlation shows that interstellar grains are not fully aligned with the Galactic magnetic field, which can be interpreted as the effect of a large random component of the field. In agreement with earlier studies of more limited scope, we estimate the ratio of the uniform to the random plane-of-the-sky components of the magnetic field to be B_u/B_r = 0.8. Moreover, a clear correlation exists between polarization degree and polarization angle what provides evidence that the magnetic field geometry follows Galactic structures on large-scales. The angular power spectrum C_l of the starlight polarization degree for Galactic plane data (|b| < 10 deg) is consistent with a power-law, C_l ~ l^{-1.5} (where l ~ 180 deg/\theta is the multipole order), for all angular scales \theta > 10 arcmin. An investigation of sparse and inhomogeneous sampling of the data shows that the starlight data analyzed traces an underlying polarized continuum that has the same power spectrum slope, C_l ~ l^{-1.5}. Our findings suggest that starlight data can be safely used for the modeling of Galactic polarized continuum emission at other wavelengths.Comment: 31 pages, 11 figures. Minor corrections and some clarifications included. Matches version accepted for publication by the Astrophysical Journa

Redox Signaling is Essential for Insulin Secretion

In this review, we place redox signaling in pancreatic β-cells to the context with signaling pathways leading to insulin secretion, acting for example upon the action of incretins (GLP-1, GIP) and the metabotropic receptor GPR40. Besides a brief description of ion channel participation in depolarization/repolarization of the plasma membrane, we emphasize a prominent role of the elevated glucose level in pancreatic β-cells during glucose-stimulated insulin secretion (GSIS). We focus on our recent findings, which revealed that for GSIS, not only elevated ATP synthesis is required, but also fundamental redox signaling originating from the NADPH oxidase 4- (NOX4-) mediated H2O2 production. We hypothesized that the closing of the ATP-sensitive K+ channel (KATP) is only possible when both ATP plus H2O2 are elevated in INS-1E cells. KATP alone or with synergic channels provides an element of logical sum, integrating both metabolic plus redox homeostasis. This is also valid for other secretagogues, such as branched chain ketoacids (BCKAs); and partly for fatty acids (FAs). Branched chain aminoacids, leucine, valine and isoleucine, after being converted to BCKAs are metabolized by a series of reactions resembling β-oxidation of FAs. This increases superoxide formation in mitochondria, including its portion elevated due to the function of electron transfer flavoprotein ubiquinone oxidoreductase (ETF:QOR). After superoxide conversion to H2O2 the oxidation of BCKAs provides the mitochondrial redox signaling extending up to the plasma membrane to induce its depolarization together with the elevated ATP. In contrast, experimental FA-stimulated insulin secretion in the presence of non-stimulating glucose concentrations is predominantly mediated by GPR40, for which intramitochondrial redox signaling activates phospholipase iPLA2γ, cleaving free FAs from mitochondrial membranes, which diffuse to the plasma membrane and largely amplify the GPR40 response. These events are concomitant to the insulin release due to the metabolic component. Hypothetically, redox signaling may proceed by simple H2O2 diffusion or via an SH-relay enabled by peroxiredoxins to target proteins. However, these aspects have yet to be elucidated

Estrategias y coordinación en el subsistema de agronegocios de cacao orgánico en la región de San Martín : el caso ACOPAGRO

Actualmente grandes cambios en las cadenas agroalimentarias causadas por los consumidores, han generado el desarrollo de productos diferenciados, que en su mayoría son producidos por pequeños productores, tal es el caso del cacao orgánico. Durante los últimos años el Perú se ha consolidado como un importante exportador de cacao fino, aromático y orgánico, siendo San Martín una de las principales regiones productoras. Este subsistema de agronegocios, presentaba serias perturbaciones, tales como, inacceso a créditos para productores, inexistencia de alianzas estratégicas, y una baja coordinación entre los actores del sistema, así mismo la existencia de intermediarios que generaban gran oportunismo e incertidumbre por el precio del cacao que percibían los productores; todo ello ocasionaba elevados costos en las transacciones. Es en este contexto que se crea la Cooperativa Agraria Cacaotera ACOPAGRO, que se ha desempeñado de manera exitosa en los últimos años, siendo líder en la exportación de cacao orgánico. De aquí parte el objetivo de esta investigación, la cual es conocer las nuevas estrategias y formas de coordinación en agronegocios, utilizando el caso ACOPAGRO. La metodología utilizada fue la epistemología fenomenológica a través de un estudio de caso. Sustentada teóricamente en la Nueva Economía Institucional aplicada a los Negocios Agroalimentarios, fundamentalmente la economía de los costos de transacción. Los resultados obtenidos definen a ACOPAGRO como subsistema estrictamente coordinado, producto de la acción colectiva, con objeto de abastecer al mercado internacional exigente. Pues esta cooperativa se ha desarrollado eficientemente, adaptándose a las distintas perturbaciones y oportunidades de mercado; estratégicamente con una innovación en su diseño organizacional que permitió implementar tecnología, crear incentivos y poder adecuar controles. Además de convertirse en el coordinador del subsistema, ACOPAGRO optó en nuevas formas de gobernancia en sus transacciones, alineándolas de tal forma que permitan salvaguardar los activos específicos invertidos por los productores y reducir la incertidumbre, bajando así los costos de transacción

In-flight calibration and verification of the Planck-LFI instrument

In this paper we discuss the Planck-LFI in-flight calibration campaign. After a brief overview of the ground test campaigns, we describe in detail the calibration and performance verification (CPV) phase, carried out in space during and just after the cool-down of LFI. We discuss in detail the functionality verification, the tuning of the front-end and warm electronics, the preliminary performance assessment and the thermal susceptibility tests. The logic, sequence, goals and results of the in-flight tests are discussed. All the calibration activities were successfully carried out and the instrument response was comparable to the one observed on ground. For some channels the in-flight tuning activity allowed us to improve significantly the noise performance.Comment: Long technical paper on Planck LFI in flight calibration campaign: 109 pages in this (not final) version, 100 page in the final JINST versio

Elevated ratio of acylated to unacylated ghrelin in children and young adults with Prader–Willi syndrome

Prader–Willi syndrome (PWS) is characterized by a switch from failure to thrive to excessive weight gain and hyperphagia in early childhood. Hyperghrelinemia may be involved in the underlying mechanisms of the switch. The purpose of this study is to evaluate acylated ghrelin (AG) and unacylated ghrelin (UAG) levels in PWS and investigate their associations with hyperphagia. This is a cross-sectional clinical study conducted in three PWS expert centers in the Netherlands and France. Levels of AG and UAG and the AG/UAG ratio were determined in 138 patients with PWS (0.2–29.4 years) and compared with 50 age-matched obese subjects (4.3–16.9 years) and 39 healthy controls (0.8–28.6 years). AEBSF was used to inhibit deacylation of AG. As a group, PWS patients had higher AG but similar UAG levels as healthy controls (AG 129.1 vs 82.4 pg/ml, p = 0.016; UAG 135.3 vs 157.3 pg/ml, resp.), resulting in a significantly higher AG/UAG ratio (1.00 vs 0.61, p = 0.001, resp.). Obese subjects had significantly lower AG and UAG levels than PWS and controls (40.3 and 35.3 pg/ml, resp.), but also a high AG/UAG ratio (1.16). The reason for the higher AG/UAG ratio in PWS and obese was, however, completely different, as PWS had a high AG and obese a very low UAG. PWS patients without weight gain or hyperphagia had a similar AG/UAG ratio as age-matched controls, in contrast to those with weight gain and/or hyperphagia who had an elevated AG/UAG ratio. The switch to excessive weight gain in PWS seems to coincide with an increase in the AG/UAG ratio, even prior to the start of hyperphagia

Attenuated cerebrospinal fluid leukocyte count and sepsis in adults with pneumococcal meningitis: a prospective cohort study

BACKGROUND: A low cerebrospinal fluid (CSF) white-blood cell count (WBC) has been identified as an independent risk factor for adverse outcome in adults with bacterial meningitis. Whereas a low CSF WBC indicates the presence of sepsis with early meningitis in patients with meningococcal infections, the relation between CSF WBC and outcome in patients with pneumococcal meningitis is not understood. METHODS: We examined the relation between CSF WBC, bacteraemia and sepsis in a prospective cohort study that included 352 episodes of pneumococcal meningitis, confirmed by CSF culture, occurring in patients aged >16 years. RESULTS: CSF WBC was recorded in 320 of 352 episodes (91%). Median CSF WBC was 2530 per mm(3 )(interquartile range 531–6983 per mm(3)) and 104 patients (33%) had a CSF WBC <1000/mm(3). Patients with a CSF WBC <1000/mm(3 )were more likely to have an unfavourable outcome (defined as a Glasgow Outcome Scale score of 1–4) than those with a higher WBC (74 of 104 [71%] vs. 87 of 216 [43%]; P < 0.001). CSF WBC was significantly associated with blood WBC (Spearman's test 0.29), CSF protein level (0.20), thrombocyte count (0.21), erythrocyte sedimentation rate (-0.15), and C-reactive protein levels (-0.18). Patients with a CSF WBC <1000/mm(3 )more often had a positive blood culture (72 of 84 [86%] vs. 138 of 196 [70%]; P = 0.01) and more often developed systemic complications (cardiorespiratory failure, sepsis) than those with a higher WBC (53 of 104 [51%] vs. 69 of 216 [32%]; P = 0.001). In a multivariate analysis, advanced age (Odds ratio per 10-year increments 1.22, 95%CI 1.02–1.45), a positive blood culture (Odds ratio 2.46, 95%CI 1.17–5.14), and a low thrombocyte count on admission (Odds ratio per 100,000/mm(3 )increments 0.67, 95% CI 0.47–0.97) were associated with a CSF WBC <1000/mm(3). CONCLUSION: A low CSF WBC in adults with pneumococcal meningitis is related to the presence of signs of sepsis and systemic complications. Invasive pneumococcal infections should possibly be regarded as a continuum from meningitis to sepsis