3,028 research outputs found

    Effectiveness of acupoint hot compress on early puerperal rehabilitation of parturients after natural childbirth: study protocol for a prospective, multi-center, randomized controlled clinical trial

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    Early puerperal rehabilitation can interfere with a woman's ability to care for herself and her infant. Acupoint hot compress, with a combination of acupoints and natural physical agent heat, has significant potential to alleviate symptoms experienced during early puerperium. Current evidence regarding the effects of acupoint hot compress therapy on early puerperal rehabilitation is insufficient. The aim of this study is to address this with a multi-center design and large sample size. This is a prospective, multi-center, and randomized controlled clinical trial. A total of 1400 nulliparous women with a singleton pregnancy experiencing natural childbirth from 14 hospitals will be enrolled and randomly allocated to either an intervention group or a control group in a 1:1 ratio. Subjects in the control group will only receive routine postpartum care. In addition to routine postpartum care, the subjects in the intervention group will be administered a 4-hour acupoint hot compress with a constant temperature of 45±2°C respectively within 30 minutes after delivery, 24 hours and 48 hours after delivery. The primary outcome will be the time elapsed from delivery to the first urination. The secondary outcomes will be postpartum uterine contraction pain intensity, the Edinburgh Postnatal Depression Scale for screening postpartum depression and the assessment of lactation including recording the lactation initiation time, postpartum diet, appetite, weight, neonatal weight. These results will provide evidence for obstetricians and parturients on considering nonpharmacologic and noninvasive intervention in early puerperal rehabilitation

    Seroconversion to Pandemic (H1N1) 2009 Virus and Cross-Reactive Immunity to Other Swine Influenza Viruses

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    To assess herd immunity to swine influenza viruses, we determined antibodies in 28 paired serum samples from participants in a prospective serologic cohort study in Hong Kong who had seroconverted to pandemic (H1N1) 2009 virus. Results indicated that infection with pandemic (H1N1) 2009 broadens cross-reactive immunity to other recent subtype H1 swine viruses

    Evaluating airline delays : the role of airline networks, schedules, and passenger demands

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    Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2009.Includes bibliographical references (p. 141-143).In this thesis, we develop a framework for analyzing airlines' operational performances under different strategic decisions. A detailed study is conducted to compare differences between a major U.S. legacy carrier and a major U.S. low-cost carrier in terms of their scheduling practices, flight-based delays and on-time performances, network operations and mix of passengers, as well as passenger delays and disruptions. One major contribution of this thesis is that the framework we develop to evaluate airlines' performances is not restricted by the availability of proprietary airline data and can be adopted to estimate itinerary-based passenger demand for any U.S. airline included in the Bureau of Transportation Statistics database. Moreover, in this thesis, we compute delay for local and connecting passengers and provide a powerful tool for scenario analysis. Further, we: (1) identify root causes of delays as well as the impact throughout the network; (2) gain insights about how passenger delay can be reduced with different scheduling practices; and (3) guide the design of on-time performance metrics. Differences in scheduling practices, network operations, passenger mix, aircraft delays, and passenger delays between different airlines arise from carrier-specific characteristics. These characteristics should be considered when designing on-time performance metrics.(cont.) Characteristics specific to the legacy carrier are: (1) its hubs experience heavy traffic volume and are often subject to ground delay programs (GDPs) caused by poor weather conditions; and (2) it operates banked hubs where a set of arriving flight legs are scheduled closely with a set of departing flight legs to allow passenger connections between arriving and departing flight legs. Characteristics specific to the low-cost carrier are: (1) it tends to fly into locations that are less impacted by weather conditions and less frequently subjected to GDPs; (2) passenger traffic is distributed more evenly in the system, unlike the case of the legacy carrier in which a much larger portion of passengers connect through the major hubs; and (3) it has depeaked schedules at the major airports which allow the carrier to achieve higher efficiency in turning aircraft. Another important distinction between the two airlines that needs to be considered when designing on-time performance metrics is: the ratio of passenger delay (especially disrupted passenger delay) to operated flight delay for the low-cost carrier was higher than the corresponding value for the legacy carrier. This difference indicates that flight-specific on-time performance metrics that ignore airline heterogeneity can be an inaccurate measure of passenger experiences. In this thesis, scenario representations pertaining to various levels of airport traffic under different weather conditions are analyzed within our framework. We measure passenger delays (that is, the positive difference between the actual arrival time of the passenger at his/her destination and the scheduled arrival time) and passenger disruptions, with a passenger disruption defined as a passenger who is re-booked on an itinerary other than that planned due to a missed connection or flight cancellation.(cont.) Our results show that for the legacy carrier, an increase in flight operations of one percent on the "high-delay" day translates to an increase in the percentage of disrupted passengers (average disrupted passenger delay) of 22.2% (3.1%); for the low-cost carrier, an increase in flight operations of one percent only increases the percentage of disrupted passengers (average disrupted passenger delay) by 12.3% (2.7%). The above statistics suggest that under poor weather conditions, increasing flight operations at busy airports, compared to non-congested airports, can cause a much greater increase in passenger delay and disruptions when airport capacity is reduced by adverse weather condition.by Ying Zhu.S.M

    Roto-vibrational spectrum and Wigner crystallization in two-electron parabolic quantum dots

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    We provide a quantitative determination of the crystallization onset for two electrons in a parabolic two-dimensional confinement. This system is shown to be well described by a roto-vibrational model, Wigner crystallization occurring when the rotational motion gets decoupled from the vibrational one. The Wigner molecule thus formed is characterized by its moment of inertia and by the corresponding sequence of rotational excited states. The role of a vertical magnetic field is also considered. Additional support to the analysis is given by the Hartree-Fock phase diagram for the ground state and by the random-phase approximation for the moment of inertia and vibron excitations.Comment: 10 pages, 8 figures, replaced by the published versio

    Discovery and Observations of ASASSN-13db, an EX Lupi-Type Accretion Event on a Low-Mass T Tauri Star

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    We discuss ASASSN-13db, an EX Lupi-type ("EXor") accretion event on the young stellar object (YSO) SDSS J051011.01-032826.2 (hereafter SDSSJ0510) discovered by the All-Sky Automated Survey for SuperNovae (ASAS-SN). Using archival photometric data of SDSSJ0510 we construct a pre-outburst spectral energy distribution (SED) and find that it is consistent with a low-mass class II YSO near the Orion star forming region (d420d \sim 420 pc). We present follow-up photometric and spectroscopic observations of the source after the ΔV\Delta V \sim-5.4 magnitude outburst that began in September 2013 and ended in early 2014. These data indicate an increase in temperature and luminosity consistent with an accretion rate of 107\sim10^{-7} M\rm{M}_\odot yr1^{-1}, three or more orders of magnitude greater than in quiescence. Spectroscopic observations show a forest of narrow emission lines dominated by neutral metallic lines from Fe I and some low-ionization lines. The properties of ASASSN-13db are similar to those of the EXor prototype EX Lupi during its strongest observed outburst in late 2008.Comment: 14 pages, 4 figures, 1 table. Updated May 2014 to reflect changes in the final version published in ApJL. Photometric data presented in this submission are included as ancillary files. For a brief video explaining this paper, see http://youtu.be/yRCCrNJnvt

    Anisotropy of the superconducting state properties and phase diagram of MgB2 by torque magnetometry on single crystals

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    The angular and temperature dependence of the upper critical field Hc2 in MgB2 was determined from torque magnetometry measurements on single crystals. The Hc2 anisotropy gamma_H was found to decrease with increasing temperature, in disagreement with the anisotropic Ginzburg-Landau theory, which predicts that the gamma_H is temperature independent. This behaviour can be explained by the two band nature of superconductivity in MgB2. An analysis of measurements of the reversible torque in the mixed state yields a field dependent effective anisotropy gamma_eff, which can be at least partially explained by different anisotropies of the penetration depth and the upper critical field. It is shown that a peak effect in fields of about 0.85 Hc2 is a manifestation of an order-disorder phase transition of vortex matter. The H-T phase diagram of MgB2 for H//c correlates with the intermediate strength of thermal fluctuations in MgB2, as compared to those in high and low Tc superconductors.Comment: 12 pages, 8 figures, Physica C in print (invited paper for a special issue on MgB2

    Dynamics of the self-interacting chameleon cosmology

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    In this article we study the properties of the flat FRW chameleon cosmology in which the cosmic expansion of the Universe is affected by the chameleon field and dark energy. In particular, we perform a detailed examination of the model in the light of numerical analysis. The results illustrate that the interacting chameleon filed plays an important role in late time universe acceleration and phantom crossing.Comment: 13 pages, 8 figures, to appear in Astrophysics and Space Sc

    Quantum interference in the fluorescence of a molecular system

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    It has been observed experimentally [H.R. Xia, C.Y. Ye, and S.Y. Zhu, Phys. Rev. Lett. {\bf 77}, 1032 (1996)] that quantum interference between two molecular transitions can lead to a suppression or enhancement of spontaneous emission. This is manifested in the fluorescent intensity as a function of the detuning of the driving field from the two-photon resonance condition. Here we present a theory which explains the observed variation of the number of peaks with the mutual polarization of the molecular transition dipole moments. Using master equation techniques we calculate analytically as well as numerically the steady-state fluorescence, and find that the number of peaks depends on the excitation process. If the molecule is driven to the upper levels by a two-photon process, the fluorescent intensity consists of two peaks regardless of the mutual polarization of the transition dipole moments. If the excitation process is composed of both a two-step one-photon process and a one-step, two-photon process, then there are two peaks on transitions with parallel dipole moments and three peaks on transitions with antiparallel dipole moments. This latter case is in excellent agreement with the experiment.Comment: 11 pages, including 8 figure
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