705 research outputs found

    Discussion and Presentation of the Disability Test Results from the Current Population Survey

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    In accordance with Executive Order 13078, the Bureau of Labor Statistics, in cooperation with the Employment Rate Measurement Methodology interagency workgroup, identified the goal of placing a small set of questions within the Current Population Survey (CPS) to measure disability. A set of potential questions was drawn from existing surveys, cognitively tested, and placed in the National Comorbidity Survey (NCS) for testing. Based on an analysis of the NCS data, a set of seven questions was identified. These seven questions were then cognitively tested to ensure that they would work within the CPS context. This question set was placed in the February 2006 CPS for field testing. The two primary goals of the test were to compare the CPS disability rate to that obtained from the NCS, and to evaluate the effect on CPS response rates in the following month. Analysis of the test data revealed a lower overall disability rate as measured in the CPS than in the NCS, with lower positive response rates for each question. The data did not indicate that there was an adverse effect on the response rates for households that had received the disability questions.Disability, Current Population Survey

    Radiation Efficiency Improvement of Zeroth-Order Resonator Antenna

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    The radiation as well as antenna efficiency of very thin profile zeroth-order resonator (ZOR) antenna, implemented in negative phase velocity (NPV) microstrip transmission line (TL) structure, has been solved by the method of moment simulator IE3D. The radiation is investigated using individual portions of the ZOR antenna that shows significant values of the surface current density. Dominantly radiating parts have been identified, geometrically emphasized by means of the increase in the antenna height over the ground plane from 1/105 to 1/8 λ0. The measured parameters of the improved antenna prototype have been enhanced so they reached the following values (compared to original ones): gain 5.0 dBi (-3.0 dBi), antenna efficiency 97.7 % (9.5 %)

    Shielded Micro-Coplanar CRLH TL Zeroth-Order Resonator Antenna: Critical Performance Evaluation

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    The attention of this paper is focused on the four unit cell zeroth-order resonator antenna (ZORA), manufactured on a shielded micro-coplanar composite right/left-handed (CRLH) transmission line structure. The antenna was designed to achieve a broadside patch-type radiation pattern. The dimensions of the antenna element follow: 15.6 x 9.35 x 3.1 mm (i.e. 0.27 x 0.16 x 0.05 λ0 at the measured zeroth-order resonance f0 = 5.14 GHz) with the shielded plane of the size of 60 x 40 mm (approx. 1.0 x 0.7 λ0). The measured gain and the antenna efficiency are equal to 4.6 dBi and 48 %, respectively. The performance of the proposed ZORA is subject to critical evaluation based on the comparison with the reference quarter-wavelength patch antenna (QWPA) that has the same dimensions. It has been found that ZORA provides comparable or even better parameters to those of QWPA, except of the bandwidth, which is much narrower in case of ZORA. In comparison to QWPA, the main advantage of the proposed ZORA might be then seen in the possibility to produce the entire ZORA structure by means of the integrated microstrip technology with air bridges. In contrary to it, the fabrication of the QWPA requires the use of either the foam substrate or plastic support pins or the application of ridged self-supporting metal plates

    Collinear Microstrip Patch Antenna

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    The paper presents a brief overview of the development of so called collinear types of antenna arrays. A new type of this structure in microstrip technology is further introduced. The principle of the antenna operation is explained via surface current distribution of excited modes. Such distribution is reached via geometrical perturbation of a radiating element by slots introduced in such a way that they e liminate radiation from even half current wavelengths . The initial design and optimization of the prototype operating in RFID band (869 MHz) has been performed in planar simulator Zeland IE3D. A prototype has been realized and measured. The reached results show that the presented antenna has directional character as it can be expected due to the proposed technology and the presence of a planar ground plane

    Microwave Antennas and Circuits Modeling Using Electromagnetic Field Simulator

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    Electromagnetic field simulators have become a widely used tool in a design process of microwave circuits and systems. A proper usage of electromagnetic (EM) field simulators allows substantial reduction of the design time providing reliable results. In such case the required parameters of the designed circuit can be reached even at the first manufactured prototype in spite of high complexity of the structure. However, EM simulation as a numerical process suffers from systematic and random errors similar to measurement using real equipment. Thus the setting of the EM-field simulator such as a frequency range, mesh properties, usage of PEC and PMC walls etc. has to be done with the highest attention and the simulation results have to be always verified using well-established techniques. The aim of the paper is to demonstrate the selected capability of EM-field simulators with a few examples of antenna and circuit modeling. Also an issue of reliability and simulation errors will be discussed

    State-space average modelling of converters with parasitics and storage-time modulation

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    The State-Space Averaging approach to modelling switching converter power stages is used to extend the analytical descriptions of the buck, boost, buck-boost, and Cuk converters to included the effects of all parasitic resistances and transistor storage-time modulation. The analysis reveals for the first time a new and unexpected term in the line to ouput response of the Cuk converter. The new term contains a right half-plane zero produced by the energy transfer capacitance in combination with the duty-ratio-weighted sum of the on-resistances of the transistor and diode plus a non-dissipative ac resistance term due to transistor storage-time modulation. The conventional circuit model of the converter is modified to include the effects of the new term. The improved model permits an eas physical interpretation of the new zero, which has been observed only the in Cuk converter. An extended analysis of storage-time modulation in bipolar transistor switches shows that the ac small-signal performance of a switching converter is highly dependent on the nature of the base drive. It is demonstrated that storage-time modulation in conjunction with a proportional base drive can produce instability in switching converters, even open-loop. The results of these analyses are verified experimentally and their impacts on practical converters are discussed

    A Comparison between Lynch Syndrome and Sporadic Colorectal Cancer Survivors’ Satisfaction with their Healthcare Providers

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    This study evaluated provider satisfaction in a sample of colorectal cancer (CRC) survivors with and without Lynch syndrome (LS). Participants were case–case-matched CRC survivors with (n=75) or without (n=75) LS (mean age of 55; range: 27–93). Participants completed a mailed questionnaire assessing demographics, clinical characteristics, healthcare utilization, psychosocial variables, and provider satisfaction. LS CRC survivors reported lower provider satisfaction scores on three subscales of the Primary Care Assessment Survey: communication (78.14 vs. 83.96; P\u3c0.05), interpersonal treatment (78.58 vs. 85.30; P\u3c0.05), and knowledge of the patient (60.34 vs. 69.86; P\u3c0.01). Among LS CRC survivors, predictors for mean communication and trust subscale scores were location of treatment and socioeconomic status. Higher mean depression scores also were associated with trust, while social support predicted higher satisfaction with communication. Sporadic CRC survivor satisfaction is driven largely by age (communication, interpersonal treatment) and patient anxiety (communication), while seeing a provider more often was associated with increased satisfaction with knowledge of the patient. LS CRC survivors reported lower levels of provider satisfaction than sporadic CRC survivors. LS survivors who received care at The University of Texas MD Anderson Cancer Center, a comprehensive cancer center (CCC), reported higher satisfaction than those receiving care at other institutions. Depressive symptoms and socioeconomic status may impact provider satisfaction ratings. Exploration of other potential predictors of provider satisfaction should be examined in this population. Additionally, further research is needed to examine the potential impact of provider satisfaction on adherence to medical recommendations in LS CRC survivors, particularly those being treated outside of CCCs

    Dynamics of the dispersion interaction in an energy transfer system

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    On the propagation of resonant radiation through an optically dense system, photon capture is commonly followed by one or more near-field transfers of the resulting optical excitation. The process invokes secondary changes to the local electronic environment, shifting the electromagnetic interactions between participant chromophores and producing modified intermolecular forces. From the theory it emerges that energy transfer, when it occurs between chromophores with electronically dissimilar properties, can itself generate significant changes in the intermolecular potentials. This report highlights specific effects that can be anticipated when laser light propagates across an interface between differentially absorbing components in a model energy transfer system
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