1,619 research outputs found
WIDE-ANGLE LIQUID CRYSTAL POLARIZATION SWITCH
A polarization switch includes a pair of liquid crystal cells operating in counter-phase such that the thickness-direction retardation of the polarization switch is substantially independent on the switching state, and thus may be passively compensated by a fixed retarder. A passive compensation structure is provided to convert the input polarization state to the first polarization state together with the first LC cell in the undriven state, and to convert the input polarization state to the second polarization state together with the second LC cell in the undriven state
Chronological records of climate-related events and societal consequences [abstract]
EXTRACT (SEE PDF FOR FULL ABSTRACT):
A chronology of documented regional and global warm and cold event records is collated along with documented ecosystem response records and health threat/sequellae records for the historical period. Patterns of societal response to cold periods punctuated by warm periods have been associated with considerable human health impacts, stimulated by blooms in disease vectors such as rodents and insects
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A Brief Overview of the History of Fish Culture and its Relation to Fisheries Sciences
The brief historical occurrence of aquaculture introduces the science that evolved from the early studies on cod propagation in 1864, and the export of these concepts about stock enhancement through protection of early life history stages through what has always been considered the âcritical periodsâ during which the majority of natural mortality takes place. The next most important issues discussed are the whyâs and howâs of fish culture, and where the habitat and feed comes from, and the related social and ecological enigmas
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Climate and Fisheries: Costs and Benefits of Change
Many records provide the bases for a clearer understanding of the roles of climate regime shifts and short-term perturbations in ecosystem dynamics, hence fisheries responses. Too few have taken the long view of the role of humans in this "Grand Fugue". As one of many predators, it is imperative that humans begin to understand that our various activities are subject to basic ecological principles, such as the concepts of growth limitations imposed by scarcities and habitat debilitations. Most of human history (evolution, growth, colonizations, displacements, resource scarcity, competition for resources) are direct consequences of normal, natural climate fluctuations, and local, regional and global ecological responses. Early fisheries were subsistence levels, with some situations where fishing communities bartered or traded for goods from adjacent highlands or forest cultures. We have also become extremely vulnerable to any persistent climate changes. Following the Medieval Warm period (~900-1180), the onset of the Little Ice Age (LIA) brought changes in regional productivity, disease, and death that began the global transition from Feudal society to the "pay as you go" economics that now dominate the world's major economies. Over the recent two to three centuries humans have swarmed over the remaining terrain, and spread out onto the seas. Modern history relates the continuous growth, expansion and generalized superposition of industrial fisheries onto older coastal subsistence communities, initiating extensive competition, overexploitation, and with resultant dwindling resources and habitat destruction. I have started a Timeline of Fisheries Development that provides a framework of information upon which these facts are derived: I will continue to develop the Timeline, so that others might learn how humans resolve the issues of complex aquatic ecosystems, limited resource sharing, or not.KEYWORDS: Climate, Fisheries, History, Cultures, Economics, Ecosystems, Environment
Racial and Ethnic Differences in Serum Cotinine Levels of Cigarette Smokers Third National Health and Nutrition Examination Survey, 1988-1991
Context.â Cotinine, a metabolite of nicotine, is a marker of exposure to tobacco smoke. Previous studies suggest that non-Hispanic blacks have higher levels of serum cotinine than non-Hispanic whites who report similar levels of cigarette smoking.
Objective.â To investigate differences in levels of serum cotinine in black, white, and Mexican American cigarette smokers in the US adult population.
Design.â Third National Health and Nutrition Examination Survey, 1988-1991.
Participants.â A nationally representative sample of persons aged 17 years or older who participated in the survey.
Outcome Measures.â Serum cotinine levels by reported number of cigarettes smoked per day and by race and ethnicity.
Results.â A total of 7182 subjects were involved in the study; 2136 subjects reported smoking at least 1 cigarette in the last 5 days. Black smokers had cotinine concentrations substantially higher at all levels of cigarette smoking than did white or Mexican American smokers (P\u3c.001). Serum cotinine levels for blacks were 125 nmol/L (22 ng/mL) (95% confidence interval [CI], 79-176 nmol/L [14-31 ng/mL]) to 539 nmol/L (95 ng/mL) (95% CI, 289-630 nmol/L [51-111 ng/mL]) higher than for whites and 136 nmol/L (24 ng/mL) (95% CI, 85-182 nmol/L [15-32 ng/mL]) to 641 nmol/L (113 ng/mL) (95% CI, 386-897 nmol/L [68-158 ng/mL]) higher than for Mexican Americans. These differences do not appear to be attributable to differences in environmental tobacco smoke exposure or in number of cigarettes smoked.
Conclusions.â To our knowledge, this study provides the first evidence from a national study that serum cotinine levels are higher among black smokers than among white or Mexican American smokers. If higher cotinine levels among blacks indicate higher nicotine intake or differential pharmacokinetics and possibly serve as a marker of higher exposure to cigarette carcinogenic components, they may help explain why blacks find it harder to quit and are more likely to experience higher rates of lung cancer than white smokers
Redesigning the Warren Animal Shelter
The new shelter should incorporate improved natural lighting and ventilation, adequate space for laundry facilities and more space for the animals\u27 living and bathing needs. The design should consider how to prevent dogs from barking and disturbing one another while in the kennels. Increased storage is necessary for the animal shelter to contain the food and living amenities for the incoming animals
Search for New Physics with Jets and Missing Transverse Momentum in pp collisions at sqrt(s) = 7 TeV
A search for new physics is presented based on an event signature of at least
three jets accompanied by large missing transverse momentum, using a data
sample corresponding to an integrated luminosity of 36 inverse picobarns
collected in proton--proton collisions at sqrt(s)=7 TeV with the CMS detector
at the LHC. No excess of events is observed above the expected standard model
backgrounds, which are all estimated from the data. Exclusion limits are
presented for the constrained minimal supersymmetric extension of the standard
model. Cross section limits are also presented using simplified models with new
particles decaying to an undetected particle and one or two jets
X-ray emission from the Sombrero galaxy: discrete sources
We present a study of discrete X-ray sources in and around the
bulge-dominated, massive Sa galaxy, Sombrero (M104), based on new and archival
Chandra observations with a total exposure of ~200 ks. With a detection limit
of L_X = 1E37 erg/s and a field of view covering a galactocentric radius of ~30
kpc (11.5 arcminute), 383 sources are detected. Cross-correlation with Spitler
et al.'s catalogue of Sombrero globular clusters (GCs) identified from HST/ACS
observations reveals 41 X-rays sources in GCs, presumably low-mass X-ray
binaries (LMXBs). We quantify the differential luminosity functions (LFs) for
both the detected GC and field LMXBs, whose power-low indices (~1.1 for the
GC-LF and ~1.6 for field-LF) are consistent with previous studies for
elliptical galaxies. With precise sky positions of the GCs without a detected
X-ray source, we further quantify, through a fluctuation analysis, the GC LF at
fainter luminosities down to 1E35 erg/s. The derived index rules out a
faint-end slope flatter than 1.1 at a 2 sigma significance, contrary to recent
findings in several elliptical galaxies and the bulge of M31. On the other
hand, the 2-6 keV unresolved emission places a tight constraint on the field
LF, implying a flattened index of ~1.0 below 1E37 erg/s. We also detect 101
sources in the halo of Sombrero. The presence of these sources cannot be
interpreted as galactic LMXBs whose spatial distribution empirically follows
the starlight. Their number is also higher than the expected number of cosmic
AGNs (52+/-11 [1 sigma]) whose surface density is constrained by deep X-ray
surveys. We suggest that either the cosmic X-ray background is unusually high
in the direction of Sombrero, or a distinct population of X-ray sources is
present in the halo of Sombrero.Comment: 11 figures, 5 tables, ApJ in pres
Combined search for the quarks of a sequential fourth generation
Results are presented from a search for a fourth generation of quarks
produced singly or in pairs in a data set corresponding to an integrated
luminosity of 5 inverse femtobarns recorded by the CMS experiment at the LHC in
2011. A novel strategy has been developed for a combined search for quarks of
the up and down type in decay channels with at least one isolated muon or
electron. Limits on the mass of the fourth-generation quarks and the relevant
Cabibbo-Kobayashi-Maskawa matrix elements are derived in the context of a
simple extension of the standard model with a sequential fourth generation of
fermions. The existence of mass-degenerate fourth-generation quarks with masses
below 685 GeV is excluded at 95% confidence level for minimal off-diagonal
mixing between the third- and the fourth-generation quarks. With a mass
difference of 25 GeV between the quark masses, the obtained limit on the masses
of the fourth-generation quarks shifts by about +/- 20 GeV. These results
significantly reduce the allowed parameter space for a fourth generation of
fermions.Comment: Replaced with published version. Added journal reference and DO
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