Permissive norms and young adults' alcohol and marijuana use: The role of online communities

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106614/1/Permissive norms and young adults' alcohol and marijuana use The role of online communities.pd

Innovative recruitment using online networks: Lessons learned from an online study of alcohol and other drug use utilizing a web-based Respondent Driven Sampling (webRDS) strategy

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106623/1/Innovative recruitment using online networks Lessons learned from an online study of alcohol and other drug use utilizing a web-based Respondent Driven Sampling webRDS strategy.pd

Use of high resolution 3D diffusion tensor imaging to study brain white matter development in live neonatal rats

High resolution diffusion tensor imaging (DTI) can provide important information on brain development, yet it is challenging in live neonatal rats due to the small size of neonatal brain and motion-sensitive nature of DTI. Imaging in live neonatal rats has clear advantages over fixed brain scans, as longitudinal and functional studies would be feasible to understand neuro-developmental abnormalities. In this study, we developed imaging strategies that can be used to obtain high resolution 3D DTI images in live neonatal rats at postnatal day 5 (PND5) and PND14, using only 3 h of imaging acquisition time. An optimized 3D DTI pulse sequence and appropriate animal setup to minimize physiological motion artifacts are the keys to successful high resolution 3D DTI imaging. Thus, a 3D rapid acquisition relaxation enhancement DTI sequence with twin navigator echoes was implemented to accelerate imaging acquisition time and minimize motion artifacts. It has been suggested that neonatal mammals possess a unique ability to tolerate mild-to-moderate hypothermia and hypoxia without long term impact. Thus, we additionally utilized this ability to minimize motion artifacts in magnetic resonance images by carefully suppressing the respiratory rate to around 15/min for PND5 and 30/min for PND14 using mild-to-moderate hypothermia. These imaging strategies have been successfully implemented to study how the effect of cocaine exposure in dams might affect brain development in their rat pups. Image quality resulting from this in vivo DTI study was comparable to ex vivo scans. fractional anisotropy values were also similar between the live and fixed brain scans. The capability of acquiring high quality in vivo DTI imaging offers a valuable opportunity to study many neurological disorders in brain development in an authentic living environment

A comparison of twice-daily exenatide and biphasic insulin aspart in patients with type 2 diabetes who were suboptimally controlled with sulfonylurea and metformin: a non-inferiority study

WSTĘP. Celem opisanego w niniejszym artykule, trwającego 52 tygodnie otwartego badania klinicznego typu non-inferiority (sprawdzenie, czy badany lek spełnia warunek nie mniejszej skuteczności) było porównanie bezpieczeństwa i skuteczności eksenatydu (leku stymulującego efekt inkretynowy) oraz dwufazowej insuliny aspart. MATERIAŁ I METODY. Pacjentów uprzednio leczonych metforminą i pochodnymi sulfonylomocznika losowo przydzielano do grupy, w której stosowano eksenatyd (n = 253; 5 &#956;g 2 x d. przez 4 tygodnie, następnie 10 &#956;g 2 x d.) lub do grupy leczonej dwufazową insuliną aspart (n = 248; 2 x d. w dawkach odpowiednich do uzyskania optymalnej kontroli glikemii). W czasie trwania badania wszyscy pacjenci kontynuowali przyjmowanie metforminy i pochodnych sulfonylomocznika. WYNIKI. Kontrola glikemii w trakcie leczenia eksenatydem nie była gorsza od wartości stwierdzanych w grupie otrzymującej dwufazową insulinę aspart [wartość średnia &#177; SEM; zmiana stężenia HbA1c: eksenatyd -1,04 &#177; 0,07%, dwufazowa insulina aspart -0,89 &#177; 0,06%: różnica -0,15% (95% CI: -0,32 do 0,01)]. U pacjentów przyjmujących eksenatyd stwier dzano spadek masy ciała, natomiast w grupie leczonej dwufazową insuliną aspart odnotowywano przyrosty masy ciała [różnica między grupami: -5,4 kg (95% CI: -5,9 do -5,0]. Oba schematy leczenia przyczyniły się do zmniejszenia wartości glikemii na czczo (eksenatyd: -1,8 &#177; 0,2 mmol/l, p < 0,002; dwufazowa insulina aspart: -1,7 &#177; 0,2 mmol/l, p < 0,001). Większą redukcję poposiłkowych wahań glikemii rano (p < 0,001), w południe (p < 0,001) i wieczorem (p < 0,001) odnotowano wśród pacjentów leczonych eksenatydem. Odsetek pacjentów, którzy wycofali się z leczenia, wyniósł w grupie eksenatydu 21,3% (54/253), a w grupie leczonej dwufazową insuliną aspart - 10,1% (25/248). W pierwszej z wymienionych grup najczęściej występującym działaniem niepożądanym leczenia były nudności (częstość występowania: 33%; była to przyczyna zaprzestania leczenia u 3,5% pacjentów). WNIOSKI/INTERPRETACJA. Leczenie eksenatydem powodowało obniżenie stężenia HbA1c w podobnym stopniu jak zastosowanie dwufazowej insuliny aspart, ale zapewniało lepszą kontrolę glikemii po posiłkach. Postępowanie takie może więc się stać alternatywą w leczeniu cukrzycy typu 2. Stosowanie dwufazowej insuliny aspart wiązało się w badanej grupie z przyrostem masy ciała, ale także z mniejszą częstością występowania działań niepożądanych ze strony przewodu pokarmowego. Wprawdzie dostępność leków hipoglikemicznych powodujących chudnięcie można uznać za istotną zaletę (w leczeniu cukrzycy typu 2), jednak odległe skutki postępującego spadku masy ciała, obserwowanego u osób leczonych eksenatydem, wymagają przeprowadzenia dalszych badań.AIMS/HYPOTHESIS. The aim of this 52-week, openlabel, noninferiority trial was to compare the safety and efficacy of exenatide (an incretin mimetic) with that of biphasic insulin aspart. MATERIALS AND METHODS. Patients on metformin and a sulfonylurea were randomised to exenatide (n = 253; 5 &#956;g twice daily for 4 weeks, 10 &#956;g thereafter) or biphasic insulin aspart (n = 248; twice-daily doses titrated for optimal glucose control), while continuing with metformin and sulfonylurea treatment. RESULTS. Glycaemic control achieved with exenatide exenatide was non-inferior to that achieved with biphasic insulin aspart [mean &#177; SEM, HbA1c change: exenatide -1.04 &#177; 0.07%, biphasic insulin aspart -0.89 &#177; 0.06%; difference -0.15% (95% CI -0.32 to 0.01)]. Exenatide-treated patients lost weight, while patients treated with biphasic insulin aspart gained weight [betweengroup difference -5.4 kg (95% CI -5.9 to -5.0)]. Both treatments reduced fasting serum glucose (exenatide -1.8 &#177; 0.2 mmol/l; p < 0.001; biphasic insulin aspart -1.7 &#177; 0.2 mmol/l; p < 0.001). Greater reductions in postprandial glucose excursions following morning (p < 0.001), midday (p = 0.002) and evening meals (p < 0.001) were observed with exenatide. The withdrawal rate was 21.3% (54/253) for exenatide and 10.1% (25/248) for biphasic insulin aspart. Nausea (33% incidence, 3.5% discontinuation) was the most common adverse event observed with exenatide. CONCLUSIONS/INTERPRETATION. Exenatide treatment resulted in HbA1c reduction similar to biphasic insulin aspart and provided better postprandial glycaemic control, making it a potential alternative for the treatment of type 2 diabetes. Treatment with biphasic insulin aspart was associated with weight gain and lower risk of adverse gastrointestinal events. Although the availability of glucose-lowering agents associated with weight reduction may be considered a therapeutic advance, the long-term implications of progressive weight reduction observed with exenatide have yet to be defined

New Insights into White-Light Flare Emission from Radiative-Hydrodynamic Modeling of a Chromospheric Condensation

(abridged) The heating mechanism at high densities during M dwarf flares is poorly understood. Spectra of M dwarf flares in the optical and near-ultraviolet wavelength regimes have revealed three continuum components during the impulsive phase: 1) an energetically dominant blackbody component with a color temperature of T $\sim$ 10,000 K in the blue-optical, 2) a smaller amount of Balmer continuum emission in the near-ultraviolet at lambda $<$ 3646 Angstroms and 3) an apparent pseudo-continuum of blended high-order Balmer lines. These properties are not reproduced by models that employ a typical "solar-type" flare heating level in nonthermal electrons, and therefore our understanding of these spectra is limited to a phenomenological interpretation. We present a new 1D radiative-hydrodynamic model of an M dwarf flare from precipitating nonthermal electrons with a large energy flux of $10^{13}$ erg cm$^{-2}$ s$^{-1}$. The simulation produces bright continuum emission from a dense, hot chromospheric condensation. For the first time, the observed color temperature and Balmer jump ratio are produced self-consistently in a radiative-hydrodynamic flare model. We find that a T $\sim$ 10,000 K blackbody-like continuum component and a small Balmer jump ratio result from optically thick Balmer and Paschen recombination radiation, and thus the properties of the flux spectrum are caused by blue light escaping over a larger physical depth range compared to red and near-ultraviolet light. To model the near-ultraviolet pseudo-continuum previously attributed to overlapping Balmer lines, we include the extra Balmer continuum opacity from Landau-Zener transitions that result from merged, high order energy levels of hydrogen in a dense, partially ionized atmosphere. This reveals a new diagnostic of ambient charge density in the densest regions of the atmosphere that are heated during dMe and solar flares.Comment: 50 pages, 2 tables, 13 figures. Accepted for publication in the Solar Physics Topical Issue, "Solar and Stellar Flares". Version 2 (June 22, 2015): updated to include comments by Guest Editor. The final publication is available at Springer via http://dx.doi.org/10.1007/s11207-015-0708-

Accretion, Outflows, and Winds of Magnetized Stars

Many types of stars have strong magnetic fields that can dynamically influence the flow of circumstellar matter. In stars with accretion disks, the stellar magnetic field can truncate the inner disk and determine the paths that matter can take to flow onto the star. These paths are different in stars with different magnetospheres and periods of rotation. External field lines of the magnetosphere may inflate and produce favorable conditions for outflows from the disk-magnetosphere boundary. Outflows can be particularly strong in the propeller regime, wherein a star rotates more rapidly than the inner disk. Outflows may also form at the disk-magnetosphere boundary of slowly rotating stars, if the magnetosphere is compressed by the accreting matter. In isolated, strongly magnetized stars, the magnetic field can influence formation and/or propagation of stellar wind outflows. Winds from low-mass, solar-type stars may be either thermally or magnetically driven, while winds from massive, luminous O and B type stars are radiatively driven. In all of these cases, the magnetic field influences matter flow from the stars and determines many observational properties. In this chapter we review recent studies of accretion, outflows, and winds of magnetized stars with a focus on three main topics: (1) accretion onto magnetized stars; (2) outflows from the disk-magnetosphere boundary; and (3) winds from isolated massive magnetized stars. We show results obtained from global magnetohydrodynamic simulations and, in a number of cases compare global simulations with observations.Comment: 60 pages, 44 figure

A measurement of lifetime differences in the neutral D-meson system

Using a high statistics sample of photoproduced charm particles from the FOCUS experiment at Fermilab, we compare the lifetimes of neutral D mesons decaying via D0 to K- pi+ and K- K+ to measure the lifetime differences between CP even and CP odd final states. These measurements bear on the phenomenology of D0 - D0bar mixing. If the D0 to K-pi+ is an equal mixture of CP even and CP odd eigenstates, we measure yCP = 0.0342 \pm 0.0139 \pm 0.0074.Comment: 15 pages, 5 figure

Seasonal phytoplankton blooms in the North Atlantic linked to the overwintering strategies of copepods

The North Atlantic Ocean contains diverse patterns of seasonal phytoplankton blooms with distinct internal dynamics. We analyzed blooms using remotely-sensed chlorophyll a concentration data and change point statistics. The first bloom of the year began during spring at low latitudes and later in summer at higher latitudes. In regions where spring blooms occurred at high frequency (i.e., proportion of years that a bloom was detected), there was a negative correlation between bloom timing and duration, indicating that early blooms last longer. In much of the Northeast Atlantic, bloom development extended over multiple seasons resulting in peak chlorophyll concentrations in summer. Spring bloom start day was found to be positively correlated with a spring phenology index and showed both positive and negative correlations to sea surface temperature and the North Atlantic Oscillation in different regions. Based on the characteristics of spring and summer blooms, the North Atlantic can be classified into two regions: a seasonal bloom region, with a well-defined bloom limited to a single season; and a multi-seasonal bloom region, with blooms extending over multiple seasons. These regions differed in the correlation between bloom start and duration with only the seasonal bloom region showing a significant, negative correlation. We tested the hypothesis that the nearsurface springtime distribution of copepods that undergo diapause (Calanus finmarchicus, C. helgolandicus, C. glacialis, and C. hyperboreus) may contribute to the contrast in bloom development between the two regions. Peak near-surface spring abundance of the late stages of these Calanoid copepods was generally associated with areas having a well-defined seasonal bloom, implying a link between bloom shape and their abundance. We suggest that either grazing is a factor in shaping the seasonal bloom or bloom shape determines whether a habitat is conducive to diapause, while recognizing that both factors can re-enforce each other