1,292 research outputs found
Fluorescence from a few electrons
Systems containing few Fermions (e.g., electrons) are of great current
interest. Fluorescence occurs when electrons drop from one level to another
without changing spin. Only electron gases in a state of equilibrium are
considered. When the system may exchange electrons with a large reservoir, the
electron-gas fluorescence is easily obtained from the well-known Fermi-Dirac
distribution. But this is not so when the number of electrons in the system is
prevented from varying, as is the case for isolated systems and for systems
that are in thermal contact with electrical insulators such as diamond. Our
accurate expressions rest on the assumption that single-electron energy levels
are evenly spaced, and that energy coupling and spin coupling between electrons
are small. These assumptions are shown to be realistic for many systems.
Fluorescence from short, nearly isolated, quantum wires is predicted to drop
abruptly in the visible, a result not predicted by the Fermi-Dirac
distribution. Our exact formulas are based on restricted and unrestricted
partitions of integers. The method is considerably simpler than the ones
proposed earlier, which are based on second quantization and contour
integration.Comment: 10 pages, 3 figures, RevTe
Experimental study of the effect of paint on embedded automotive antennas
In years have seen the advent of new types of automotive antennas, such as blade or 'shark-fin' antennas and conformal planar roof mounted antennas. In many cases it is desirable to paint these antennas to improve the appearance of the vehicle. In this communication we present an investigation of the effect that both metallic and non-metallic two-pack polyurethane paint has on a structure radiating at approximately 1.5 GHz (GPS Ll-band), with a particular emphasis on the impedance bandwidth and radiation performance
The design and realization of uniplanar CPW fed PICA slot antennas
In modern wireless communication system design, antennas with wide impedance bandwidth are desirable for numerous reasons. An antenna with a wide impedance bandwidth may be used for transmission and reception of multiple narrowband services in a multi-purpose platform. Alternatively a single wideband service may be of interest for various radar and imaging applications, or for impulse based radio communications in the FCC ultra-wideband (UWB) regime from 3.1 GHz to 10.6 GHz
Cognitive function and lifetime features of depression and bipolar disorder in a large population sample: Cross-sectional study of 143,828 UK Biobank participants
Background: This study investigated differences in cognitive performance between middle-aged adults with and without a lifetime history of mood disorder features, adjusting for a range of potential confounders.
Methods: Cross-sectional analysis of baseline data from the UK Biobank cohort. Adults aged 40–69 (n = 143,828) were assessed using measures of reasoning, reaction time and memory. Self-reported data on lifetime features of major depression and bipolar disorder were used to construct groups for comparison against controls. Regression models examined the association between mood disorder classification and cognitive performance, adjusting for sociodemographic, lifestyle and clinical confounders.
Results: Inverse associations between lifetime history of bipolar or severe recurrent depression features and cognitive performance were attenuated or reversed after adjusting for confounders, including psychotropic medication use and current depressive symptoms. Participants with a lifetime history of single episode or moderate recurrent depression features outperformed controls to a small (but statistically significant) degree, independent of adjustment for confounders. There was a significant interaction between use of psychotropic medication and lifetime mood disorder features, with reduced cognitive performance observed in participants taking psychotropic medication.
Conclusions: In this general population sample of adults in middle age, lifetime features of recurrent depression or bipolar disorder were only associated with cognitive impairment within unadjusted analyses. These findings underscore the importance of adjusting for potential confounders when investigating mood disorder-related cognitive function
Recognizing Emotions in a Foreign Language
Expressions of basic emotions (joy, sadness, anger, fear, disgust) can be recognized pan-culturally from the face and it is assumed that these emotions can be recognized from a speaker's voice, regardless of an individual's culture or linguistic ability. Here, we compared how monolingual speakers of Argentine Spanish recognize basic emotions from pseudo-utterances ("nonsense speech") produced in their native language and in three foreign languages (English, German, Arabic). Results indicated that vocal expressions of basic emotions could be decoded in each language condition at accuracy levels exceeding chance, although Spanish listeners performed significantly better overall in their native language ("in-group advantage"). Our findings argue that the ability to understand vocally-expressed emotions in speech is partly independent of linguistic ability and involves universal principles, although this ability is also shaped by linguistic and cultural variables
Effect of photoperiod and host distribution on the horizontal transmission of Isaria fumosorosea (Hypocreales: Cordycipitaceae) in greenhouse whitefly assessed using a novel model bioassay
A model bioassay was used to evaluate the epizootic potential and determine the horizontal transmission efficiency of Isaria fumosorosea Trinidadian strains against Trialeurodes vaporariorum pharate adults under optimum conditions (25±0.5°C, ~100% RH) at two different photoperiods. Untreated pharate adults were arranged on laminated graph paper at different distributions to simulate varying infestation levels on a leaf surface. Four potential hosts were located 7, 14 and 21 mm away from a central sporulating cadaver simulating high, medium and low infestation levels, respectively. Percent hosts colonized were recorded 7, 12, 14 and 21 days post-treatment during a 16- and 24-h photophase. After 21 days, mean percent hosts colonized at the highest, middle and lowest infestation levels were 93 and 100%, 22 and 58%, 25 and 39% under a 16- and 24-h photophase, respectively. From the results, it was concluded that the longer the photophase, the greater the percentage of hosts colonized, and as host distance increased from the central sporulating cadaver, colonization decreased. The use of this novel model bioassay technique is the first attempt to evaluate the epizootic potential and determine the horizontal transmission efficiency of I. fumosorosea Trinidadian strains under optimal environmental conditions at different photoperiods. This bioassay can be used to assess horizontal transmission efficiency for the selection of fungi being considered for commercial biopesticide development
The VIMOS VLT Deep Survey - First epoch VVDS-Deep survey: 11564 spectra with 17.5<=IAB<=24, and the redshift distribution over 0< z <=5
This paper presents the ``First Epoch'' sample from the VIMOS VLT Deep Survey
(VVDS). The VVDS goals, observations, data reduction with VIPGI, and redshift
measurement with KBRED are discussed. Data have been obtained with the VIsible
Multi Object Spectrograph (VIMOS) on the ESO-VLT UT3, allowing to observe ~600
slits simultaneously at R~230. A total of 11564 objects have been observed in
the VVDS-02h and VVDS-CDFS Deep fields over a total area of 0.61deg^2, selected
solely on the basis of apparent magnitude 17.5 <=I_{AB} <=24. The VVDS covers
the redshift range 0 < z <= 5. It is successfully going through the ``redshift
desert'' 1.5<z<2.2, while the range 2.2<z<2.7 remains of difficult access
because of the VVDS wavelength coverage.A total of 9677 galaxies have a
redshift measurement, 836 are stars, 90 are AGNs, and a redshift could not be
measured for 961 objects. There are 1065 galaxies with a measured redshift
z>1.4. The survey reaches a redshift measurement completeness of 78% overall
(93% including less reliable objects), with a spatial sampling of the
population of galaxies of 25% and ~30% in the VVDS-02h and VVDS-CDFS. The
redshift accuracy measured from repeated observations with VIMOS and comparison
to other surveys is ~276km/s. From this sample we present for the first time
the redshift distribution of a magnitude limited spectroscopic sample down to
IAB=24. The redshift distribution has a median of z=0.62, z=0.65, z=0.70, and
z=0.76, for magnitude limited samples with IAB<=22.5, 23, 23.5, and 24. A high
redshift tail above redshift 2 and up to redshift 5 becomes readily apparent
for IAB>23.5, probing the bright star forming population of galaxies. This
sample provides an unprecedented dataset to study galaxy evolution over 90% of
the life of the universeComment: 30 pages, accepted 22-Feb-05 in A&
Parametric Evaluation of Communication Devices in Smart Composite Structures
This paper reports on some of the rheological results of the selected composite materials. The base material components comprise unsaturated polyester (uPE) reinforced with randomly distributed short strands of fibreglass (E type). This material is commonly known as sheet moulding compound (SMC) and is currently used in the automotive industry for different applications. This work will further look into t he parameters involved in the processing of the SMC with respect to its visco-elastic behaviour. These parameters involve viscosity, elastic and viscous modulus with respect to the processing temperature. This paper reports on some preliminary results of material processing parameters such as pressures, temperatures, cure times and volume fractions of resins, fillers and reinforcing materials. Also included is an evaluation of the electrical properties of different grades of SMC as a precursor to the encapsulation of a microstrip antenna within the material
The War Power After 200 Years: Congress and the President at a Constitutional Impasse: Hearings before the Subcommittee on War Powers of the Committee on Foreign Relations, United States Senate, One Hundredth Congress, First Session
Feasibility and Coverage of Implementing Intermittent Preventive Treatment of Malaria in Pregnant women Contacting Private or Public Clinics in Tanzania: Experience-based Viewpoints of Health Managers in Mkuranga and Mufindi districts.
Evidence on healthcare managers' experience on operational feasibility of malaria intermittent preventive treatment for malaria during pregnancy (IPTp) using sulphadoxine-pyrimethamine (SP) in Africa is systematically inadequate. This paper elucidates the perspectives of District Council Health Management Team (CHMT)s regarding the feasibility of IPTp with SP strategy, including its acceptability and ability of district health care systems to cope with the contemporary and potential challenges. The study was conducted in Mkuranga and Mufindi districts. Data were collected between November 2005 and December 2007, involving focus group discussion (FGD) with Mufindi CHMT and in-depth interviews were conducted with few CHMT members in Mkuranga where it was difficult to summon all members for FGD. Participants in both districts acknowledged the IPTp strategy, considering the seriousness of malaria in pregnancy problem; government allocation of funds to support healthcare staff training programmes in focused antenatal care (fANC) issues, procuring essential drugs distributed to districts, staff remuneration, distribution of fANC guidelines, and administrative activities performed by CHMTs. The identified weaknesses include late arrival of funds from central level weakening CHMT's performance in health supervision, organising outreach clinics, distributing essential supplies, and delivery of IPTp services. Participants anticipated the public losing confidence in SP for IPTp after government announced artemither-lumefantrine (ALu) as the new first-line drug for uncomplicated malaria replacing SP. Role of private healthcare staff in IPTp services was acknowledged cautiously because CHMTs rarely supplied private clinics with SP for free delivery in fear that clients would be required to pay for the SP contrary to government policy. In Mufindi, the District Council showed a strong political support by supplementing ANC clinics with bottled water; in Mkuranga such support was not experienced. A combination of health facility understaffing, water scarcity and staff non-adherence to directly observed therapy instructions forced healthcare staff to allow clients to take SP at home. Need for investigating in improving adherence to IPTp administration was emphasised. High acceptability of the IPTp strategy at district level is meaningless unless necessary support is assured in terms of number, skills and motivation of caregivers and availability of essential supplies
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