164 research outputs found
Optical spectroscopy of gan microcavities with thicknesses controlled using a plasma etch-back
The effect of an etch-back step to control the cavity length within GaN-based microcavities formed between two dielectric Bragg mirrors was investigated using photoluminescence and reflectivity. The structures are fabricated using a combination of a laser lift-off technique to separate epitaxial III-N layers from their sapphire substrates and electron-beam evaporation to deposit silica/zirconia multilayer mirrors. The photoluminescence measurements reveal cavity modes from both etched and nonetched microcavities. Similar cavity finesses are measured for 2.0 and 0.8 mm GaN cavities fabricated from the same wafer, indicating that the etchback has had little effect on the microcavity quality. For InGaN quantum well samples the etchback is shown to allow controllable reduction of the cavity length. Two etch steps of 100 nm are demonstrated with an accuracy of approximately 5%. The etchback, achieved using inductively coupled plasma and wet chemical etching, allows removal of the low-quality GaN nucleation layer, control of the cavity length, and modification of the surface resulting from lift-off
Cardiovascular risk management following gestational diabetes and hypertensive disorders of pregnancy: a narrative review
Gestational diabetes mellitus and hypertensive disorders of pregnancy (gestational hypertension and preeclampsia) are strong independent risk predictors for future cardiovascular disease (CVD) specific to women. Awareness of the relationship between pregnancy-related risk factors and CVD needs improvement among both women and clinicians. Education of patients and their health care providers is urgently needed to ensure preventive measures are implemented across a woman's lifespan to care for the health of women affected by these conditions. Few interventions have been developed or studied which are designed to lower CVD risk in women with pregnancy-related risk factors. Future work should focus on developing interventions that are tailored together with individual communities and integrated within health care systems, ensuring each health care provider's role is clearly outlined to effectively prevent and manage CVD in these high risk women.Simone Marschner, Anushriya Pant, Amanda Henry, Louise J Maple-Brown, Lisa Moran, N Wah Cheung, Clara K Chow, Sarah Zama
Resonant decay of gravitational waves into dark energy
We study the decay of gravitational waves into dark energy fluctuations \u3c0, taking into account the large occupation numbers. We describe dark energy using the effective field theory approach, in the context of generalized scalar-tensor theories. When the m33 (cubic Horndeski) and 3c m42 (beyond Horndeski) operators are present, the gravitational wave acts as a classical background for \u3c0 and modifies its dynamics. In particular, \u3c0 fluctuations are described by a Mathieu equation and feature instability bands that grow exponentially. Focusing on the regime of small gravitational-wave amplitude, corresponding to narrow resonance, we calculate analytically the produced \u3c0, its energy and the change of the gravitational-wave signal. The resonance is affected by \u3c0 self-interactions in a way that we cannot describe analytically. This effect is very relevant for the operator m33 and it limits the instability. In the case of the 3c m42 operator self-interactions can be neglected, at least in some regimes. The modification of the gravitational-wave signal is observable for 3
7 10-20 64 \u3b1H 64 10-17 with a LIGO/Virgo-like interferometer and for 10-16 64 \u3b1H 64 10-10 with a LISA-like one
Ablation plasma ion implantation using a dc power supply
Experiments are reported in which ablation plasma ion implantation (APII) has been demonstrated using a dc power supply. The ability to use a dc power supply for APII has been accomplished by using a perpendicular orientation between the target and the substrate. This perpendicular orientation significantly reduces the arcing between the target and the substrate, in contrast to previous experiments using a parallel targetâsubstrate orientation. With this new technique a KrF laser may be fired during the dc high voltage, accelerating full-energy ions. Initial experiments using dc APII have shown that Ti is deposited and implanted onto the Si substrate, with the highest concentration of Ti located beneath the surface of the film. The deposition/implantation of Ti ions onto Si was verified by X-ray photoelectron spectroscopy.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47038/1/339_2004_Article_2585.pd
On primordial trispectrum from exchanging scalar modes in general multiple field inflationary models
We make an complementary investigation of the primordial trispectrum from
exchanging intermediate scalar modes in multi-field inflation models with
generalized kinetic terms. Together with the calculation of irreducible
contributions to the primordial trispectrum in Ref.[103], we give the full
leading-order primordial trispectrum in generalized multi-field models.Comment: 15 pages, 1 figure; v2 references adde
The relationship between body mass index and sleep in women with risk factors for gestational diabetes mellitus
OnlinePublBackground: Both obesity and sleep disorders are common among women during pregnancy. Although prior research has identified a relationship between obesity and sleep disorders, those findings are from women later in pregnancy. Objective: To explore the relationships between selfâreported sleep duration, insufficient sleep and snoring with body mass index (BMI) among multiethnic women at risk of gestational diabetes mellitus (GDM)in early pregnancy.Methods: Crossâsectional study of baseline data from women at risk of GDM enrolled in the Treatment of BOoking Gestational diabetes Mellitus (TOBOGM) multicentre trial across 12 Australian/Austrian sites. Participants completed a questionnaire before 20 weeksâ gestation to evaluate sleep. BMI 5 days/ month was higher in class II and class III obesity (1.38 (1.03â1.85) and 1.34 (1.01â 1.80), respectively), and the risk of snoring increased as BMI increased (1.59 (1.25â 2.02), 2.68 (2.07â3.48), 4.35 (3.21â5.88) to 4.96 (3.65â6.74), respectively)). Conclusions: Obesity is associated with insufficient sleep among pregnant women at risk of GDM. Snoring is more prevalent with increasing BMI.Pamela Acosta Reyes, Jincy Immanuel, William M. Hague, Helena Teede, Emily Hibbert, Christopher J. Nolan, Michael J. Peek, Vincent Wong, Jeffrey R. Flack, Mark McLean, Raiyomand Dalal, JĂŒrgen Harreiter, Alexandra Kautzky, Willer, Rohit Rajagopal, Arianne Sweeting, Glynis P. Ross, Ngai Wah Cheung, David Simmon
Cosmological Constraints on Decaying Dark Matter
We present a complete analysis of the cosmological constraints on decaying
dark matter. Previous analyses have used the cosmic microwave background and
Type Ia supernova. We have updated them with the latest data as well as
extended the analysis with the inclusion of Lyman- forest, large scale
structure and weak lensing observations. Astrophysical constraints are not
considered in the present paper. The bounds on the lifetime of decaying dark
matter are dominated by either the late-time integrated Sachs-Wolfe effect for
the scenario with weak reionization, or CMB polarization observations when
there is significant reionization. For the respective scenarios, the lifetimes
for decaying dark matter are Gyr and Gyr (at 95.4% confidence level), where the
phenomenological parameter is the fraction of the decay energy deposited in
baryonic gas. This allows us to constrain particle physics models with dark
matter candidates through investigation of dark matter decays into Standard
Model particles via effective operators. For decaying dark matter of
GeV mass, we found that the size of the coupling constant in the effective
dimension-4 operators responsible for dark matter decay has to generically be . We have also explored the implications of our analysis for
representative models in theories of gauge-mediated supersymmetry breaking,
minimal supergravity and little Higgs.Comment: 29 pages, 6 figures. Added references and corrected typos as well as
grammatical oversight
Spectrum of pheochromocytoma in the 131 I-MIBG era
131 I-metaiodobenzylguanidine ( 131 I-MIBG) scintigraphy allows for both functional diagnosis and anatomical localization of pheochromocytoma. The spectrum of pheochromocytoma since the routine use of preoperative 131 I-MIBG scan was studied. From 1980 to 1986, a total of 34 patients were primarily diagnosed and treated at the University of Michigan Medical Center, Ann Arbor, Michigan, U.S.A. There were 16 males and 18 females. The mean age was 38 years and 4 patients (11.8%) were under 18 years of age. Six patients (17.6%) had family history of pheochromocytoma or multiple endocrine neoplasia (MEN) II syndrome. The presenting symptoms were hypertension in 29 patients (85.3%); attacks of headache, palpitation, sweating, and flushing in 4 (11.8%), and 1 patient presented with a neck mass. Plasma catecholamines were elevated in 97% of patients while urinary catecholamines and metabolites were elevated in 93.5%. 131 I-MIBG was accurate in 82.3%, partly positive in 11.8%, and false-negative in 5.9% of patients. CT scan was accurate in 80%, partly positive in 10%, but failed to show the tumor in another 10% of patients. At operation, extraadrenal lesions were found in 38.2% of the patients and among these, one-third were extraabdominal. Multiple tumors occurred in 5 (14.7%), and bilateral adrenal lesions occurred in 4 patients (11.8%). Malignancy was diagnosed in 3 patients (8.8%) after an average follow-up period of 2 years. We conclude that the use of routine preoperative 131 I-MIBG scanning improves localization of pheochromocytoma and earlier diagnosis is possible in patients with MEN II syndrome. Multiple tumors, extraadrenal and extraabdominal lesions occur more often than commonly believed. The low rate of confirmed malignancy is probably related to the short period of follow-up. La scintigraphie Ă l' 131 I-MIBG permet de diagnostiquer et de localiser les phĂ©ochromocytomes. Toute la gamme de types de phĂ©ochromocytomes reconnu depuis l'utilisation prĂ©opĂ©ratoire systĂ©matique de la scintigraphie Ă l' 131 I-MIBG est prĂ©sentĂ©e. Entre 1980 et 1986, 34 patients ont Ă©tĂ© explorĂ©s et traitĂ©s au Centre MĂ©dical de l'UniversitĂ© de Michigan, Ann Arbor, Michigan. Il y avait 16 hommes et 18 femmes. L'Ăąge moyen Ă©tait de 38 ans, et 4 patients (11.8%) avaient moins de 18 ans. Six patients (17.6%) avaient des antĂ©cĂ©dents familiaux de phĂ©ochromocytome ou de nĂ©oplasmes endocrines multiples (MEN) du type II. Les symptĂŽmes amenant Ă consulter Ă©taient l'hypertension chez 29 patients (85.3%), des crises de cĂ©phalĂ©es, des palpitations et un flush chez 4 patients (11.8%); un patient prĂ©sentait une masse cervicale. Les catĂ©cholamines plasmatiques Ă©taient Ă©levĂ©es chez 97% des patients alors que les catĂ©cholamines et leurs mĂ©tabolites Ă©taient en quantitĂ© Ă©levĂ©e chez 93.5% des patients. La scintigraphie Ă l' 131 I-MIBG Ă©tait positive chez 82.3%, partiellement positive chez 11.8%, et faussement nĂ©gative chez 5.9% des patients. La tomodensitomĂ©trie Ă©tait positive chez 80%, partiellement positive chez 10%, et faussement nĂ©gative chez 10% des patients. A l'intervention, des lĂ©sions extra-surrĂ©nales Ă©taient prĂ©sentes dans 38.2% des cas, et parmi celles-ci, un tiers Ă©taient extra-abdominales. Les tumeurs Ă©taient multiples dans 5 cas (14.7%), et bilatĂ©rales surrĂ©nales dans 4 cas (11.8%). Une tumeur maligne Ă©tait diagnostiquĂ©e chez 3 patients (8.8%), aprĂšs une pĂ©riode de suivi de 2 ans en moyenne. Nous concluons que l'utilisation systĂ©matique de la scintigraphie Ă l' 131 I-MIBG amĂ©liore la localisation des phĂ©ochromocytomes, permettant un diagnostic plus prĂ©coce chez les patients prĂ©sentant un syndrome MEN II. La multiplicitĂ© tumorale et les localisations extra-mĂ©dullosurrĂ©nales ou extra-abdominales se voient beaucoup plus frĂ©quemment qu'on le pensait auparavant. Le taux de malignitĂ© peu Ă©levĂ© Ă©tait probablement en rapport avec la courte pĂ©riode de suivi. La escintigrafĂa con 131 I-MIBG permite tanto la localizaciĂłn anatĂłmica como el diagnĂłstico funcional del feocromocitoma. Las caracterĂsticas o espectro del feocromocitoma a partir del uso rutinario de 131 I-MIBG han sido estudiadas.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/41282/1/268_2005_Article_BF01655447.pd
Dialysis initiation, modality choice, access, and prescription: conclusions from a Kidney Disease: Improving Global Outcomes (KDIGO) Controversies Conference
Globally, the number of patients undergoing maintenance dialysis is increasing, yet throughout the world there is significant variability in the practice of initiating dialysis. Factors such as availability of resources, reasons for starting dialysis, timing of dialysis initiation, patient education and preparedness, dialysis modality and access, as well as varied \u201ccountry-specific\u201d factors significantly affect patient experiences and outcomes. As the burden of end-stage kidney disease (ESKD) has increased globally, there has also been a growing recognition of the importance of patient involvement in determining the goals of care and decisions regarding treatment. In January 2018, KDIGO (Kidney Disease: Improving Global Outcomes) convened a Controversies Conference focused on dialysis initiation, including modality choice, access, and prescription. Here we present a summary of the conference discussions, including identified knowledge gaps, areas of controversy, and priorities for research. A major novel theme represented during the conference was the need to move away from a \u201cone-size-fits-all\u201d approach to dialysis and provide more individualized care that incorporates patient goals and preferences while still maintaining best practices for quality and safety. Identifying and including patient-centered goals that can be validated as quality indicators in the context of diverse health care systems to achieve equity of outcomes will require alignment of goals and incentives between patients, providers, regulators, and payers that will vary across health care jurisdictions
Search for dark matter produced in association with a hadronically decaying vector boson in pp collisions at sqrt (s) = 13 TeV with the ATLAS detector
A search is presented for dark matter produced in association with a hadronically decaying W or Z boson using 3.2 fbâ1 of pp collisions at View the MathML sources=13 TeV recorded by the ATLAS detector at the Large Hadron Collider. Events with a hadronic jet compatible with a W or Z boson and with large missing transverse momentum are analysed. The data are consistent with the Standard Model predictions and are interpreted in terms of both an effective field theory and a simplified model containing dark matter
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