1,911 research outputs found
Effects of human recombinant growth hormone on exercise capacity, cardiac structure, and cardiac function in patients with adult-onset growth hormone deficiency
Objective Epidemiological studies suggest that adult-onset growth hormone deficiency (AGHD) might increase the risk of death from cardiovascular causes. Methods This was a 6-month double-blind, placebo-controlled, randomised, cross-over trial followed by a 6-month open-label phase. Seventeen patients with AGHD received either recombinant human growth hormone (rGH) (0.4 mg injection daily) or placebo for 12 weeks, underwent washout for 2 weeks, and were then crossed over to the alternative treatment for a further 12 weeks. Cardiac magnetic resonance imaging, echocardiography, and cardiopulmonary exercise testing were performed at baseline, 12 weeks, 26 weeks, and the end of the open phase (12 months). The results were compared with those of 16 age- and sex-matched control subjects. Results At baseline, patients with AGHD had a significantly higher systolic blood pressure, ejection fraction, and left ventricular mass than the control group, even when corrected for body surface area. Treatment with rGH normalised the insulin-like growth factor 1 concentration without an effect on exercise capacity, cardiac structure, or cardiac function. Conclusion Administration of rGH therapy for 6 to 9 months failed to normalise the functional and structural cardiac differences observed in patients with AGHD when compared with a control group
A Hybrid Variational Iteration Method for Blasius Equation
The objective of this paper is to present the hybrid variational iteration method. The proposed algorithm is based on the combination of variational iteration and shooting methods. In the proposed algorithm the entire domain is divided into subintervals to establish the accuracy and convergence of the approximate solution. It is found that in each subinterval a three term approximate solution using variational iteration method is sufficient. The proposed hybrid variational iteration method offers not only numerical values, but also closed form analytic solutions in each subinterval. The method is implemented using an example of the Blasius equation. The results show that a hybrid variational iteration method is a powerful technique for solving nonlinear problems
Stretching a Surface Having a Layer of Porous Medium in a Viscous Fluid
The present analysis deals with the steady, incompressible flow of a viscous fluid over a stretching sheet having a layer of porous medium of uniform thickness. The two-dimensional flow equations are derived in a Cartesian coordinate system. The semi-infinite region filled with a viscous fluid is divided into two regions namely, a clear fluid region and a region having a uniform pores. Darcy\u27s law has been used for the flow of fluid in the porous medium region. An exact similar solution of the problem is obtained. The obtained solution is constrained by a relation between the porosity parameter and the parameter representing the viscosity ratios between the two regions. Our interest lies in determining the influence of porosity parameter, viscosities ratio parameter and thickness of the porous layer on the fluid velocity and the skin friction coefficient. The results for the Crane\u27s problem in a complete clear and a complete porous region are retrieved as special cases of the present solution
Performance Analysis of Cooperative V2V and V2I Communications under Correlated Fading
Cooperative vehicular networks will play a vital role in the coming years to
implement various intelligent transportation-related applications. Both
vehicle-to-vehicle (V2V) and vehicle-to-infrastructure (V2I) communications
will be needed to reliably disseminate information in a vehicular network. In
this regard, a roadside unit (RSU) equipped with multiple antennas can improve
the network capacity. While the traditional approaches assume antennas to
experience independent fading, we consider a more practical uplink scenario
where antennas at the RSU experience correlated fading. In particular, we
evaluate the packet error probability for two renowned antenna correlation
models, i.e., constant correlation (CC) and exponential correlation (EC). We
also consider intermediate cooperative vehicles for reliable communication
between the source vehicle and the RSU. Here, we derive closed-form expressions
for packet error probability which help quantify the performance variations due
to fading parameter, correlation coefficients and the number of intermediate
helper vehicles. To evaluate the optimal transmit power in this network
scenario, we formulate a Stackelberg game, wherein, the source vehicle is
treated as a buyer and the helper vehicles are the sellers. The optimal
solutions for the asking price and the transmit power are devised which
maximize the utility functions of helper vehicles and the source vehicle,
respectively. We verify our mathematical derivations by extensive simulations
in MATLAB.Comment: Internet of Vehicles (IoV), Vehicular communication, Antenna
correlation, Stackelberg game, Vehicle-to-infrastructure (V2I),
Vehicle-to-vehicle (V2V), Game theory, Cooperative vehicular network
Clear Experimental Signature of Charge-Orbital density wave in NdCaMnO
Single Crystals of NdCaMnO have been prepared by the
travelling floating-zone method, and possible evidence of a charge -orbital
density wave in this material presented earlier [PRB68,092405 (2003)] using
High Resolution Electron Microscopy [HRTEM] and Electron Diffraction [ED]. In
the current note we present direct evidence of charge-orbital ordering in this
material using heat capacity measurements. Our heat capacity measurements
indicate a clear transition consistent with prior observation. We find two main
transitions, one at temperature K, and other at
K. In addition, we may also conclude that there is a strong electron-phonon
coupling in this material.Comment: 7 pages, 8 figure
The role of guanxi networks in the performance of women-led firms in China
This exploratory paper examines how knowledge acquired via guanxi (networks and connections) have enabled women-led firms in China to overcome a number of significant barriers and challenges in order to start and grow a successful business. We draw upon two case studies, in order to illustrate how they have utilized guanxi as a means of overcoming these barriers. We investigate the way in which guanxi facilitates the business owner in engaging in a process of entrepreneurial learning (Harrison and Leitch 2005; Politis, 2008) – and making connections and contacts – by which she is able to improve the firm’s performance. Further research is necessary to build upon a small number of studies that have already cleared the ground in terms of guanxi. More reliable and country-wide, but disaggregated, statistics on small businesses would be a welcome start, including information on their owner-manager’s or owner-managers’ gender
Meteorological Drought Analysis and Return Periods over North and West Africa and Linkage with El Niño−Southern Oscillation (ENSO)
Droughts are one of the world’s most destructive natural disasters. In large regions of Africa, droughts can have strong environmental and socioeconomic impacts. Understanding the mechanism that drives drought and predicting its variability is important for enhancing early warning and disaster risk management. Taking North and West Africa as the study area, this study adopted multi-source data and various statistical analysis methods, such as the joint probability density function (JPDF), to study the meteorological drought and return years across a long term (1982−2018). The standardized precipitation index (SPI) was used to evaluate the large-scale spatiotemporal drought characteristics at 1−12-month timescales. The intensity, severity, and duration of drought in the study area were evaluated using SPI−12. At the same time, the JPDF was used to determine the return year and identify the intensity, duration, and severity of drought. The Mann-Kendall method was used to test the trend of SPI and annual precipitation at 1−12-month timescales. The pattern of drought occurrence and its correlation with climate factors were analyzed. The results showed that the drought magnitude (DM) of the study area was the highest in 2008−2010, 2000−2003, and 1984−1987, with the values of 5.361, 2.792, and 2.187, respectively, and the drought lasting for three years in each of the three periods. At the same time, the lowest DM was found in 1997−1998, 1993−1994, and 1991−1992, with DM values of 0.113, 0.658, and 0.727, respectively, with a duration of one year each time. It was confirmed that the probability of return to drought was higher when the duration of drought was shorter, with short droughts occurring more regularly, but not all severe droughts hit after longer time intervals. Beyond this, we discovered a direct connection between drought and the North Atlantic Oscillation Index (NAOI) over Morocco, Algeria, and the sub-Saharan countries, and some slight indications that drought is linked with the Southern Oscillation Index (SOI) over Guinea, Ghana, Sierra Leone, Mali, Cote d’Ivoire, Burkina Faso, Niger, and Nigeria
"Enter the dragoness": Firm growth, finance, guanxi, and gender in China
Purpose: The purpose of this exploratory paper is to theorise and examine gender differences in the impact of financial capital on Chinese firms' growth, and investigate the role of guanxi (connections and networks) in the process of obtaining finance. Design/methodology/approach: A structured questionnaire is used to collect comprehensive financial data from 18 women to 69 men, which is analysed empirically. Findings: Women appear to be no more disadvantaged from obtaining finance than men in China and in some respects appear to be in a better position. Both women- and men-led firms are significantly stronger in relation to having access to enough finance to grow than at the start-up phase. A majority of participants in this study used guanxi to access finance. Furthermore, the paper finds that guanxi is used equally by men and women, and that guanxi-sourced finance comprised a significant proportion of the overall capital obtained. Research limitations/implications: One major limitation of the study is that, of the 87 questionnaires returned, 21 per cent are women and 79 per cent are men and, although the findings are not representative or generalisable, the results do suggest a number of possible avenues for future research. Originality/value: The paper has illuminated the under-explored area of the financing of growth in women-led firms in China. This research agenda is particularly important because small- and medium-sized enterprise finance in China is a key need-to-know area, there is a paucity of specific research on financing women entrepreneurs in China and of the phenomenal rise of women's entrepreneurship in China. © Emerald Group Publishing Limited
CCL11 (eotaxin‐1): A new diagnostic serum marker for prostate cancer
BACKGROUND The recent recommendation of the U.S. Preventive Services Task Force against PSA‐based screening for prostate cancer was based, in part, on the lack of demonstrated diagnostic utility of serum PSA values in the low, but detectable range to successfully predict prostate cancer. Though controversial, this recommendation reinforced the critical need to develop, validate, and determine the utility of other serum and/or urine transcript and protein markers as diagnostic markers for PCa. The studies described here were intended to determine whether inflammatory cytokines might augment serum PSA as a diagnostic marker for prostate cancer. METHODS Multiplex ELISA assays were performed to quantify CCL1, CCL2, CCL5, CCL8, CCL11, CCL17, CXCL1, CXCL5, CXCL8, CXCL10, CXCL12, and IL‐6 protein levels in the serum of 272 men demonstrating serum PSA values of <10 ng/ml and undergoing a 12 core diagnostic needle biopsy for detection of prostate cancer. Logistic regression was used to identify the associations between specific chemokines and prostate cancer status adjusted for prostate volume, and baseline PSA. RESULTS Serum levels for CCL1 (I‐309) were significantly elevated among all men with enlarged prostates ( P < 0.04). Serum levels for CCL11 (Eotaxin‐1) were significantly elevated among men with prostate cancer regardless of prostate size ( P < 0.01). The remaining 10 cytokines examined in this study did not exhibit significant correlations with either prostate volume or cancer status. CONCLUSIONS Serum CCL11 values may provide a useful diagnostic tool to help distinguish between prostatic enlargement and prostate cancer among men demonstrating low, but detectable, serum PSA values. Prostate 73: 573–581, 2013. © 2012 Wiley Periodicals, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97458/1/22597_ftp.pd
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