2,678 research outputs found

    Photometric binary content in intermediate/old open clusters

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    The stellar evolutionary models by Bertelli et al. (1994) have been used to generate synthetic colour-magnitude diagrams (CMDs) of open clusters. A comparison of the synthetic integrated luminosity function (ILF) and synthetic colour distribution with the corresponding observed distributions is used to estimate the photometric binary content in three intermediate age open clusters, which is found to be about 30% in these clusters

    High sensitivity and multifunctional micro-Hall sensors fabricated using InAlSb/InAsSb/InAlSb heterostructures

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    Further diversification of Hall sensor technology requires development of materials with high electron mobility and an ultrathin conducting layer very close to the material's surface. Here, we describe the magnetoresistive properties of micro-Hall devices fabricated using InAlSb/InAsSb/InAlSb heterostructures where electrical conduction was confined to a 30 nm-InAsSb two-dimensional electron gas layer. The 300 K electron mobility and sheet carrier concentration were 36 500 cm(2) V-1 s(-1) and 2.5 x 10(11) cm(-2), respectively. The maximum current-related sensitivity was 2 750 V A(-1) T-1, which was about an order of magnitude greater than AlGaAs/InGaAs pseudomorphic heterostructures devices. Photolithography was used to fabricate 1 mu m x 1 mu m Hall probes, which were installed into a scanning Hall probe microscope and used to image the surface of a hard disk

    Clinical Thermoradiotherapy

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    A clinical trial is currently in progress to determine the efficacy of combined fractions of hyperthermia and radiation. The protocol consists of two parts. First, four fractions of microwave-induced hyperthermia (45.0° ± 0.5°C) are applied for 1 1/2 hours to the volume encompassing the tumor, each separated by 72 hours. After a one-week rest, a second series of four fractions is administered again at 72- hour intervals. Each fraction consists of a 400 rad dose of radiation followed within 20 minutes by hyperthermia (42.5 ± 0.5°C) for 1 1/2 hours. Currently, we have treated 62 patients with 82 fields with a mean follow-up time of six months to date. Total regression was observed in 60% of all cases, and partial regression in 33%; no response was seen in only 6% of all those treated. Five local and three marginal recurrences have been observed. This paper discusses details of response based on site, histology, and classification

    Stellar contents of two intermediate age clusters: NGC 1912 and NGC 1907

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    We present CCD photometry in a wide field around two open clusters, NGC 1912 and NGC 1907. The stellar surface density profiles indicate that the radii of the clusters NGC 1912 and NGC 1907 are ~14' and ~6' and respectively. The core of the cluster NGC 1907 is found to be 1'.6۪'3, whereas the core of the cluster NGC 1912 could not be defined due to its significant variation with the limiting magnitude. The clusters are situated at distances of 1400±100 pc (NGC 1912) and 1760±100pc (NGC 1907), indicating that in spite of their close locations on the sky they may be formed in different parts of the Galaxy. Although the mass functions for the clusters are quite noisy, in the given mass range the slopes of the mass functions for clusters NGC 1912 and NGC 1907 turn out to be -1.12 ±0.30 and -1.23 ± 0.21, respectively, which are in agreement with the Salpeter value. Because the ages of the clusters are much higher than the estimated relaxation time-scales, dynamical relaxation may be one of the reasons for the observed mass segregation in the clusters. A comparison of the observed CMDs of the clusters with the synthetic CMDs gives a photometric binary content as 30± 10% (mass range 1.0 ≤M⊙ ≤3.1) and 20±10% (mass range 1.2 ≤M⊙ ≤3.2 ) in the case of NGC 1912 and NGC 1907, respectively

    Integrated parameters of star clusters: A comparison of theory and observations

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    (Abridged) This paper presents integrated magnitude and colours for synthetic clusters. The integrated parameters have been obtained for the whole cluster population as well as for the main-sequence (MS) population of star clusters. We have also estimated observed integrated magnitudes and colours of MS population of galactic open clusters, LMC and SMC star clusters. It is found that the colour evolution of MS population of star clusters is not affected by the stochastic fluctuations, however these fluctuations significantly affect the colour evolution of the whole cluster population. The fluctuations are maximum in (VI)(V-I) colour in the age range 6.7 << log (age) << 7.5. Evolution of integrated colours of MS population of the clusters in the Milky Way, LMC and SMC, obtained in the present study are well explained by the present synthetic cluster model. The observed integrated (BV)(B-V) colours of MS population of LMC star clusters having age \geq 500 Myr seem to be distributed around Z=Z= 0.004 model, whereas (VI)(V-I) colours are found to be more bluer than those predicted by the Z=Z= 0.004 model. (VI)(V-I) vs (BV)(B-V) two-colour diagram for the MS population of the Milky Way star clusters shows a fair agreement between the observations and present model, however the diagrams for LMC and SMC clusters indicate that observed (VI)(V-I) colours are relatively bluer. Possible reasons for this anomaly have been discussed.Comment: 35 pages, 20 figs, accepted for publication in MNRA

    The Changing Eigenfrequency Continuum during Geomagnetic Storms:Implications for Plasma Mass Dynamics and ULF Wave Coupling

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    Geomagnetic storms are one of the most energetic space weather phenomena. Previous studies have shown that the eigenfrequencies of ultralow frequency (ULF) waves on closed magnetic field lines in the inner magnetosphere decrease during storm times. This change suggests either a reduction in the magnetic field strength and/or an increase in its plasma mass density distribution. We investigate the changes in local eigenfrequencies by applying a superposed multiple‐epoch analysis to cross‐phase spectra from 132 geomagnetic storms. Six ground magnetometer pairs are used to investigate variations from approximately 3 4, the eigenfrequencies decrease by as much as 50% relative to their quiet time values. Both a decrease in magnetic field strength and an increase in plasma mass density, in some locations by more than a factor of 2, are responsible for this reduction. The enhancement of the ring current and an increase in oxygen ion density could explain these observations. At L < 4, the eigenfrequencies increase due to the decrease in plasma mass density caused by plasmaspheric erosion

    Visitor Access Control Scheme Utilizing Social Relationship in the Real World

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    L 552 : A new bold seeded variety of kabuli gram

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    Chickpea (Cicer arietinum L.) is an important pulse crop grown during rabi season in Punjab state. Major objective in breeding of kabuli gram is development of high yielding and bold seeded varieties as they fetch higher price in the market. The efforts lead to the development of a new variety of kabuli gram L 552 from the cross GLK 95091 x PBG 68 through pedigree method of selection. This new variety has been recommended during 2011 for general cultivation in irrigated areas of Punjab state except submountainous regions

    Feasibility of vocal fold abduction and adduction assessment using cine-MRI

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    OBJECTIVE: Determine feasibility of vocal fold (VF) abduction and adduction assessment by cine magnetic resonance imaging (cine-MRI) METHODS: Cine-MRI of the VF was performed on five healthy and nine unilateral VF paralysis (UVFP) participants using an axial gradient echo acquisition with temporal resolution of 0.7 s. VFs were continuously imaged with cine-MRI during a 10-s period of quiet respiration and phonation. Scanning was repeated twice within an individual session and then once again at a 1-week interval. Asymmetry of VF position during phonation (VF phonation asymmetry, VFPa) and respiration (VF respiration asymmetry, VFRa) was determined. Percentage reduction in total glottal area between respiration and phonation (VF abduction potential, VFAP) was derived to measure overall mobility. An un-paired t-test was used to compare differences between groups. Intra-session, inter-session and inter-reader repeatability of the quantitative metrics was evaluated using intraclass correlation coefficient (ICC). RESULTS: VF position asymmetry (VFPa and VFRa) was greater (p=0.012; p=0.001) and overall mobility (VFAP) was lower (p=0.008) in UVFP patients compared with healthy participants. ICC of repeatability of all metrics was good, ranged from 0.82 to 0.95 except for the inter-session VFPa (0.44). CONCLUSION: Cine-MRI is feasible for assessing VF abduction and adduction. Derived quantitative metrics have good repeatability. KEY POINTS: • Cine-MRI is used to assess vocal folds (VFs) mobility: abduction and adduction. • New quantitative metrics are derived from VF position and abduction potential. • Cine-MRI able to depict the difference between normal and abnormal VF mobility. • Cine-MRI derived quantitative metrics have good repeatability

    A test of general relativity from the three-dimensional orbital geometry of a binary pulsar

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    Binary pulsars provide an excellent system for testing general relativity because of their intrinsic rotational stability and the precision with which radio observations can be used to determine their orbital dynamics. Measurements of the rate of orbital decay of two pulsars have been shown to be consistent with the emission of gravitational waves as predicted by general relativity, providing the most convincing evidence for the self-consistency of the theory to date. However, independent verification of the orbital geometry in these systems was not possible. Such verification may be obtained by determining the orientation of a binary pulsar system using only classical geometric constraints, permitting an independent prediction of general relativistic effects. Here we report high-precision timing of the nearby binary millisecond pulsar PSR J0437-4715, which establish the three-dimensional structure of its orbit. We see the expected retardation of the pulse signal arising from the curvature of space-time in the vicinity of the companion object (the `Shapiro delay'), and we determine the mass of the pulsar and its white dwarf companion. Such mass determinations contribute to our understanding of the origin and evolution of neutron stars.Comment: 5 pages, 2 figure
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