141 research outputs found
Telecommunications Act of 1996: 704 of the Act and Protections Afforded the Telecommunications Provider in the Facilities Sitting Context, The
The Telecommunications Act of 1996, signed into law by President Clinton in February, addresses, among many other important subjects, some of the technical problems that have arisen from the increasing popularity of mobile communications. This article will provide an overview of the Act and will focus specifically on the protections afforded a telecommunications provider in § 704 of the Act
Telecommunications Act of 1996: 704 of the Act and Protections Afforded the Telecommunications Provider in the Facilities Sitting Context, The
The Telecommunications Act of 1996, signed into law by President Clinton in February, addresses, among many other important subjects, some of the technical problems that have arisen from the increasing popularity of mobile communications. This article will provide an overview of the Act and will focus specifically on the protections afforded a telecommunications provider in § 704 of the Act
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Retroactive skill of multi-tiered forecasts of summer rainfall over southern Africa
Seaâsurface temperature (SST) variations of the oceans surrounding southern Africa are associated with seasonal rainfall variability, especially during austral summer when the tropical atmospheric circulation is dominant over the region. Because of instabilities in the linear association between summer rainfall over southern Africa and SSTs of the tropical Indian Ocean, the skilful prediction of seasonal rainfall may best be achieved using physically based models. A twoâtiered retroâactive forecast procedure for the DecemberâFebruary (DJF) season is employed over a 10âyear period starting from 1987/1988. Rainfall forecasts are produced for a number of homogeneous regions over part of southern Africa. Categorized (belowânormal, nearânormal and aboveânormal) statistical DJF rainfall predictions are made for the region to form the baseline skill level that has to be outscored by more elaborate methods involving general circulation models (GCMs). The GCM used here is the Centre for OceanâLandâAtmosphere Studies (COLA) T30, with predicted global SST fields as boundary forcing and initial conditions derived from the National Centres for Environmental Prediction (NCEP) reanalysis data. Biasâcorrected GCM simulations of circulation and moisture at certain standard pressure levels are downscaled to produce rainfall forecasts at the regional level using the perfect prognosis approach.
In the twoâtiered forecasting system, SST predictions for the global oceans are made first. SST anomalies of the equatorial Pacific (NIĂO3.4) and Indian oceans are predicted skilfully at 1â and 3âmonth leadâtimes using a statistical model. These retroâactive SST forecasts are accurate for preâ1990 conditions, but predictability seems to have weakened during the 1990s. Skilful multiâtiered rainfall forecasts are obtained when the amplitudes of large events in the global oceans (such as El Niño and La Niña episodes) are described adequately by the predicted SST fields. GCM simulations using persisted August SST anomalies instead of forecast SSTs produce skill levels similar to those of the baseline for longer leadâtimes. Given highâskill SST forecasts, the scheme has the potential to provide climate forecasts that outscore the baseline skill level substantially
Fingerprints of spin-orbital physics in cubic Mott insulators: Magnetic exchange interactions and optical spectral weights
The temperature dependence and anisotropy of optical spectral weights
associated with different multiplet transitions is determined by the spin and
orbital correlations. To provide a systematic basis to exploit this close
relationship between magnetism and optical spectra, we present and analyze the
spin-orbital superexchange models for a series of representative
orbital-degenerate transition metal oxides with different multiplet structure.
For each case we derive the magnetic exchange constants, which determine the
spin wave dispersions, as well as the partial optical sum rules. The magnetic
and optical properties of early transition metal oxides with degenerate
orbitals (titanates and vanadates with perovskite structure) are shown
to depend only on two parameters, viz. the superexchange energy and the
ratio of Hund's exchange to the intraorbital Coulomb interaction, and on
the actual orbital state. In systems important corrections follow from
charge transfer excitations, and we show that KCuF can be classified as a
charge transfer insulator, while LaMnO is a Mott insulator with moderate
charge transfer contributions. In some cases orbital fluctuations are quenched
and decoupling of spin and orbital degrees of freedom with static orbital order
gives satisfactory results for the optical weights. On the example of cubic
vanadates we describe a case where the full quantum spin-orbital physics must
be considered. Thus information on optical excitations, their energies,
temperature dependence and anisotropy, combined with the results of magnetic
neutron scattering experiments, provides an important consistency test of the
spin-orbital models, and indicates whether orbital and/or spin fluctuations are
important in a given compound.Comment: 34 pages, 16 figure
Centriolar satellites expedite mother centriole remodeling to promote ciliogenesis
Centrosomes are orbited by centriolar satellites, dynamic multiprotein assemblies nucleated by Pericentriolar material 1 (PCM1). To study the requirement for centriolar satellites, we generated mice lacking PCM1, a crucial component of satellites. Pcm1â/â mice display partially penetrant perinatal lethality with survivors exhibiting hydrocephalus, oligospermia, and cerebellar hypoplasia, and variably expressive phenotypes such as hydronephrosis. As many of these phenotypes have been observed in human ciliopathies and satellites are implicated in cilia biology, we investigated whether cilia were affected. PCM1 was dispensable for ciliogenesis in many cell types, whereas Pcm1â/â multiciliated ependymal cells and human PCM1â/â retinal pigmented epithelial 1 (RPE1) cells showed reduced ciliogenesis. PCM1â/â RPE1 cells displayed reduced docking of the mother centriole to the ciliary vesicle and removal of CP110 and CEP97 from the distal mother centriole, indicating compromised early ciliogenesis. Similarly, Pcm1â/â ependymal cells exhibited reduced removal of CP110 from basal bodies in vivo. We propose that PCM1 and centriolar satellites facilitate efficient trafficking of proteins to and from centrioles, including the departure of CP110 and CEP97 to initiate ciliogenesis, and that the threshold to trigger ciliogenesis differs between cell types
Chandra Observations of the Anomalous X-ray Pulsar 4U 0142+61
We present X-ray imaging, timing, and phase resolved spectroscopy of the
anomalous X-ray pulsar 4U 0142+61 using the Chandra X-ray Observatory. The
spectrum is well described by a power law plus blackbody model with power law
index = 3.35(2), kT_BB=0.458(3) keV, and N_H=0.91(2) x 10^{22} cm^{-2}$; we
find no significant evidence for spectral features (0.5-7.0 keV). Time resolved
X-ray spectroscopy shows evidence for evolution in phase in either index, or
KT_BB, or some combination thereof as a function of pulse phase. We derive a
precise X-ray position for the source and determine its spin period,
P=8.68866(30) s. We have detected emission beyond 4 arcsec from the central
source and extending beyond 100 arcsec, likely due to dust scattering in the
interstellar medium.Comment: 15 pages, accepted for publication in Ap
A comparison of the measurement properties of the Juvenile Arthritis Functional Assessment Scale with the childhood health assessment questionnaire in daily practice
We compared the measurement properties of a performance test (Juvenile Arthritis Functional Assessment Scale; JAFAS) with a questionnaire-based instrument (Childhood Health Assessment Questionnaire; CHAQ) to measure functional ability in patients with juvenile idiopathic arthritis on the level of individual items. In 28 consecutive children visiting an outpatient paediatrics clinic, the JAFAS (range 0â20) and CHAQ (range 0â3) were applied, and measures of disease activity and joint range of motion (ROM) were determined. Twenty-eight children with a median age of 10Â years and median disease duration of 3.2Â years were included. The median JAFAS score was 0, and the median CHAQ score was 0.125. Cronbachâs alpha was 0.92 for the JAFAS and 0.96 for the CHAQ. The Spearman correlation coefficient between the JAFAS and the CHAQ was 0.55 (Pâ<â0.01). With six out of ten items, the JAFAS classified the child as less disabled than with corresponding CHAQ activities. Overall, associations with measures of disease activity and ROM were higher for the CHAQ than for the JAFAS. A performance test (JAFAS) does not appear to have an added benefit over the questionnaire-based assessment (CHAQ) of physical function in a cross-sectional study
A Rasch and factor analysis of the Functional Assessment of Cancer Therapy-General (FACT-G)
BACKGROUND: Although the Functional Assessment of Cancer Therapy â General questionnaire (FACT-G) has been validated few studies have explored the factor structure of the instrument, in particular using non-sample dependent measurement techniques, such as Rasch Models. Furthermore, few studies have explored the relationship between item fit to the Rasch Model and clinical utility. The aim of this study was to investigate the dimensionality and measurement properties of the FACT-G with Rasch Models and Factor analysis. METHODS: A factor analysis and Rasch analysis (Partial Credit Model) was carried out on the FACT-G completed by a heterogeneous sample of cancer patients (n = 465). For the Rasch analysis item fit (infit mean squares â„ 1.30), dimensionality and item invariance were assessed. The impact of removing misfitting items on the clinical utility of the subscales and FACT-G total scale was also assessed. RESULTS: The factor analysis demonstrated a four factor structure of the FACT-G which broadly corresponded to the four subscales of the instrument. Internal consistency for these four scales was very good (Cronbach's alpha 0.72 â 0.85). The Rasch analysis demonstrated that each of the subscales and the FACT-G total scale had misfitting items (infit means square â„ 1.30). All these scales with the exception of the Social & Family Well-being Scale (SFWB) were unidimensional. When misfitting items were removed, the effect sizes and the clinical utility of the instrument were maintained for the subscales and the total FACT-G scores. CONCLUSION: The results of the traditional factor analysis and Rasch analysis of the FACT-G broadly agreed. Caution should be exercised when utilising the Social & Family Well-being scale and further work is required to determine whether this scale is best represented by two factors. Additionally, removing misfitting items from scales should be performed alongside an assessment of the impact on clinical utility
Risk estimates of recurrent congenital anomalies in the UK: a population-based register study
BACKGROUND: Recurrence risks for familial congenital anomalies in successive pregnancies are known, but this information for major structural anomalies is lacking. We estimated the absolute and relative risks of recurrent congenital anomaly in the second pregnancy for women with a history of a congenital anomaly in the first pregnancy; for all major anomaly groups and subtypes.
METHODS: Population-based register data on 18,605 singleton pregnancies affected by major congenital anomaly occurring in 872,493 singleton stillbirths, live births and terminations of pregnancy for fetal anomaly were obtained from the Northern Congenital Abnormality Survey, North of England, UK, for 1985-2010. Absolute risks (ARs) and relative risks (RRs) for recurrent congenital anomaly (overall, from a similar group, from a dissimilar group) in the second pregnancy were estimated by history of congenital anomaly (overall, by group, by subtype) in the first pregnancy.
RESULTS: The estimated prevalences of congenital anomaly in first and second pregnancies were 276 (95% CI 270-281) and 163 (95% CI 159-168) per 10,000 respectively. For women whose first pregnancy was affected by congenital anomaly, the AR of recurrent congenital anomaly in the second pregnancy was 408 (95% CI 365-456) per 10,000; 2.5 (95% CI 2.3-2.8, p<0.0001) times higher than for those with unaffected first pregnancies. For similar anomalies, the recurrence risk was considerably elevated (RR=23.8, 95% CI 19.6-27.9, P<0.0001) while for dissimilar anomalies the increase was more modest (RR=1.4, 95% CI 1.2-1.6, P=0.001), although the ARs for both were 2%.
CONCLUSIONS: Absolute recurrence risks varied between 1 in 20 and 1 in 30 for most major anomaly groups. At pre-conception and antenatal counselling, women whose first pregnancy was affected by a congenital anomaly and who are planning a further pregnancy may find it reassuring that despite high relative risks, the absolute recurrence risk is relatively low
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