480 research outputs found
Is Cosmic Parity Violation Responsible for the Anomalies in the WMAP Data?
This research demonstrates that parity violation in general relativity can
simultaneously explain the observed loss in power and alignment at a preferred
axis ('Axis of Evil')in the low multipole moments of the WMAP data. This
observational possibility also provides an experimental window for an
inflationary leptogenesis mechanism arising from large-scale parity violation.
A velocity dependent potential is induced from gravitational backreaction,
which modifies the primordial scalar angular power spectrum of density
perturbations in the CMB. This modification suppresses power of odd parity
multipoles on large scales which can be associated with the scale of a massive
right-handed neutrino.Comment: 5 pages, included new references, expanded on some calculation
Detection of a Dipole in the Handedness of Spiral Galaxies with Redshifts z ~ 0.04
A preference for spiral galaxies in one sector of the sky to be left-handed
or right-handed spirals would indicate a parity violating asymmetry in the
overall universe and a preferred axis. This study uses 15158 spiral galaxies
with redshifts <0.085 from the Sloan Digital Sky Survey. An unbinned analysis
for a dipole component that made no prior assumptions for the dipole axis gives
a dipole asymmetry of -0.0408\pm0.011 with a probability of occurring by chance
of 7.9 x 10-4. A similar asymmetry is seen in the Southern Galaxy spin catalog
of Iye and Sugai. The axis of the dipole asymmetry lies at approx. (l, b)
=(52{\deg}, 68.5{\deg}), roughly along that of our Galaxy and close to
alignments observed in the WMAP cosmic microwave background distributions. The
observed spin correlation extends out to separations ~210 Mpc/h, while spirals
with separations < 20 Mpc/h have smaller spin correlations.Comment: To be published in Physics Letters
A stable -category for equivariant -theory
For a countable group we construct a small, idempotent complete,
symmetric monoidal, stable -category
whose homotopy category recovers the triangulated equivariant Kasparov category
of separable --algebras, and exhibit its universal property. Likewise,
we consider an associated presentably symmetric monoidal, stable
-category which receives a symmetric monoidal functor
from possibly non-separable --algebras and discuss
its universal property. In addition to the symmetric monoidal structures, we
construct various change-of-group functors relating these KK-categories for
varying . We use this to define and establish key properties of a (spectrum
valued) equivariant, locally finite -homology theory on proper and locally
compact -topological spaces, allowing for coefficients in arbitrary
--algebras. Finally, we extend the functor from
--algebras to --categories. These constructions are key in a
companion paper about a form of equivariant Paschke duality and assembly maps.Comment: 108 pages. Minor corrections, References update
Hypogenic Speleogenesis within Seven Rivers Evaporites: Coffee Cave, Eddy County, New Mexico
Coffee Cave, located in the lower Pecos region of southeastern New Mexico, illustrates processes of hypogenic speleogenesis in the middle Permian Seven Rivers Formation. Coffee Cave is a rectilinear gypsum maze cave with at least four stratigraphically-distinct horizons of development. Morphological features throughout the cave provide unequivocal evidence of hypogenic ascending speleogenesis in a confined aquifer system driven by mixed (forced and free) convection. Morphologic features in individual cave levels include a complete suite that defines original rising flow paths, ranging from inlets for hypogenic fluids (feeders) through transitional forms (rising wall channels) to ceiling half-tube flow features and fluid outlets (cupolas and exposed overlying beds). Passage morphology does not support origins based on epigenic processes and lateral development, although the presence of fine-grained sediments in the cave suggests minimal overprinting by backflooding. Feeder distributions show a lateral shift in ascending fluids, with decreasing dissolutional development in upper levels. It is likely that additional hypogenic karst phenomena are present in the vicinity of Coffee Cave because regional hydrologic conditions are optimum for confined speleogenesis, with artesian discharge still active in the region
New electron-rich diketiminate ligands : an experimental and computational investigation on the isolation of reactive species
1 online resource (ix, 72 p.) : ill. (some col.)Includes abstract and appendix.Includes bibliographical references (p. 61-68).Boron analogues of NHCs have long eluded detection, likely due to their predicted low singlet-to-triplet energy gap. Two new N,N’-chelating ligands have been prepared and investigations into their reactivity and coordinative properties have started. A boron carbenoid that incorporates one of the new ligands has been probed computationally using both DFT and second-order Møller-Plesset methods. It has been found that the singlet state of this carbenoid is between 13.98 and 36.85 kJ mol[superscript -1] more stable than its triplet state. To date, this is the only computationally investigated ligand system that stabilizes a neutral, six-membered heterocyclic, ground state singlet boron carbenoid. Attempts to prepare, and isolate, this compound have been unsuccessful, however, experimental evidence suggests further investigations should be made.
Organometallic complexes of the two new ligands have also been prepared and present interesting structural features. Rhodium carbonyl compounds have been synthesized with each ligand and these were studied to determine the ligands’ electronic features, in comparison to each other and to the common 1,3-diketiminate (nacnac) ligand. It was found that one was experimentally identical to nacnac and the other had increased donor capabilities. A dimethylaluminum complex has also been prepared and both X-ray and DSC studies suggest that it assumes different solid state morphologies at various temperatures. Additionally, a long, Zn⋯C [pi]type interaction was observed in the corresponding ethylzinc complex
The Pecos River Hypogene Speleogenetic Province: a Basin-Scale Karst Paradigm for Eastern New Mexico and West Texas, USA
Since the mid-Tertiary, lateral migration and entrenchment of the Pecos River Valley in eastern New Mexico and west Texas, USA, has significantly influenced regional groundwater flow paths, providing a focus for ascending flow in multi-storey artesian systems and a powerful potentiometric driving force for hypogene speleogenesis. Individual occurrences of hypogene karst phenomena associated with the central Pecos River Valley are widespread throughout the greater Delaware Basin region, including development in a wide range of Permian carbonate and evaporate fades. Hypogene occurrences are well-documented as far north as Santa Rosa, New Mexico and as far south as Lake Amistad, Texas. Throughout the northern shelf, intrastratal dissolution and brecciation of the San Andres formation is widespread as a result of eastward migration of the Pecos River. Proximal to the current river, hypogene dissolution in interbedded carbonate/evaporite facies of the Seven Rivers Formation has produced three-dimensional network caves and vertical collapse structures. In the carbonate reeffacies of the Guadalupe Mountains, complex three dimensional caves are common, as well as stepped terraces associated with eastward migration of thePecos River. Although these caves have been attributed to sulfuric acid dissolution, they are the result of hypogene speleogenesis in which solutional aggressivity was increased by the addition of both thermal and sulfuric-acid components. Within the interior of the Delaware Basin, hypogene karst in basin-filling evaporite facies of the Castile and Salado Formations is widespread, including development of large solution subsidence troughs associated with the lateral migration of the Pecos River. On the far eastern margin of the Delaware Basin, at the southeastern tip of the Central Basin Platform, persistent down cutting of the Pecos River Valley contributed to the development of hypogene karst within the Yates Petroleum Field, providing cavernous reservoir porosity for the largest individual oil field known within the Permian Basin region. Immediately below the confluence of the Pecos River and the Rio Grande, the large first order magnitude spring, Goodenough Spring, flows from a deep phreatic cave under extreme artesian conditions, even as 45 meters of pressure head has been added over the spring from Amistad Reservoir
Undiscovered Karst Country: A New Paradigm for the Pecos Region of Eastern New Mexico and West Texas as a Basin-Scale, Hypogene Speleogenetic Province [Abstract]
Reduced oxygen concentration during human IVF culture improves embryo utilization and cumulative pregnancy rates per cycle
STUDY QUESTION: Do different oxygen levels during human IVF embryo culture affect embryo utilization, cumulative IVF success rates per cycle and neonatal birthweight?SUMMARY ANSWER: After 2 days of culture, a lower oxygen level (5%) leads to more good-quality embryos and more embryos that can be cryopreserved, and thereby to a higher cumulative live birth rate per cycle when compared to embryo culture in 20% oxygen, while birthweights are similar.WHAT IS KNOWN ALREADY: Several studies have compared IVF outcome parameters after embryo culture in a more physiological level of 5% oxygen and the atmospheric level of 20%. Although there is consensus that embryo development improves in 5% oxygen, effects on pregnancy and live birth rates are mainly seen in blastocyst, but not cleavage-stage transfers. A major drawback of these studies is that only fresh embryo transfers were included, not taking additional frozen-thawed transfers from these cycles into account. This might have underestimated the effects of oxygen level, especially in cleavage-stage embryo transfers. Furthermore, little is known about the effect of oxygen level during culture on birthweight.STUDY DESIGN, SIZE, DURATION: This is a cohort study in 871 consecutive patients who had an IVF cycle between January 2012 and December 2013, and 5-7 years follow-up to allow transfer of frozen-thawed embryos. Based on daily availability of positions in the incubators, all oocytes and embryos of one cycle were allocated to one of the three incubators with traditional ambient oxygen levels (6% CO2 and 20% O2 in air), or to a fourth incubator that was adjusted to have low oxygen levels of 5% (6% CO2, 5% O2 and 89% N2). Embryos were cultured under 5 or 20% oxygen until Day 2 or 3, when embryos were transferred or cryopreserved, respectively. Clinical and other laboratory procedures were similar in both groups.PARTICIPANTS/MATERIALS, SETTING, METHODS: To compare embryo characteristics and (cumulative) pregnancy outcomes between the two oxygen groups, for each patient only the first cycle in the study period was included in the analysis, resulting in 195 cycles in the 5% group (1627 oocytes) and 676 in the 20% oxygen group (5448 oocytes). Embryo characteristics were analysed per cycle and per embryo and were corrected for maternal age, cycle rank order, fertilization method (IVF or ICSI) and cause of subfertility. Perinatal data from the resulting singletons (n = 124 after fresh and 45 after frozen-thawed embryo transfer) were collected from delivery reports from the hospitals or midwife practices.MAIN RESULTS AND THE ROLE OF CHANCE: In the 5% oxygen group, there were significantly more embryos of good quality (45.8 versus 30.9% in the 20% group, adjusted odds ratio (OR) [95% CI] = 1.9 [1.6-2.4]). This did not result in higher live birth rates per cycle, but after fresh transfers more good-quality spare embryos could be cryopreserved (46.1 versus 29.7%, adjusted OR [95% CI] = 2.0 [1.7-2.5]). After a follow-up period of 5-7 years, in which 82.4% of the cryopreserved embryos from the 5% oxygen group and 85.4% from the 20% oxygen group were thawed, the percentage of patients with at least one live birth resulting from the study cycle was significantly higher in the low oxygen group (adjusted OR [95% CI] = 1.5 [1.01-2.2]). In 124 live born singletons from fresh embryo transfers and in 45 from transfers of cryopreserved embryos, birthweight was similar in both oxygen groups after correction for confounding factors.LIMITATIONS, REASONS FOR CAUTION: This is a retrospective study, and treatment allocation was not randomised. The study was not powered for a predefined birthweight difference. With the number of live births in our study, small differences in birthweight might not have been detected. The selection of embryos to be cryopreserved was based on embryo morphology criteria that might be different in other clinics.WIDER IMPLICATIONS OF THE FINDINGS: Improved embryo utilization by more cryopreservation leading to higher cumulative live birth rates per cycle favours the use of 5% instead of 20% oxygen during human IVF embryo culture. This study also demonstrates that for comparison of different IVF treatment regimens, the cumulative outcome, including transfers of fresh and frozen-thawed embryos, is to be preferred instead of analysis of fresh embryo transfers only.STUDY FUNDING/COMPETING INTEREST(S): No external funding was received for this study. None of the authors has a conflict of interest to declare.</p
Opioid overdose deaths and potentially inappropriate opioid prescribing practices (PIP): A spatial epidemiological study
INTRODUCTION: Opioid overdose deaths quintupled in Massachusetts between 2000 and 2016. Potentially inappropriate opioid prescribing practices (PIP) are associated with increases in overdoses. The purpose of this study was to conduct spatial epidemiological analyses of novel comprehensively linked data to identify overdose and PIP hotspots.
METHODS: Sixteen administrative datasets, including prescription monitoring, medical claims, vital statistics, and medical examiner data, covering \u3e98% of Massachusetts residents between 2011-2015, were linked in 2017 to better investigate the opioid epidemic. PIP was defined by six measures: \u3e /=100 morphine milligram equivalents (MMEs), co-prescription of benzodiazepines and opioids, cash purchases of opioid prescriptions, opioid prescriptions without a recorded pain diagnosis, and opioid prescriptions through multiple prescribers or pharmacies. Using spatial autocorrelation and cluster analyses, overdose and PIP hotspots were identified among 538 ZIP codes.
RESULTS: More than half of the adult population (n = 3,143,817, ages 18 and older) were prescribed opioids. Nearly all ZIP codes showed increasing rates of overdose over time. Overdose clusters were identified in Worcester, Northampton, Lee/Tyringham, Wareham/Bourne, Lynn, and Revere/Chelsea (Getis-Ord Gi*; p \u3c 0.05). Large PIP clusters for \u3e /=100 MMEs and prescription without pain diagnosis were identified in Western Massachusetts; and smaller clusters for multiple prescribers in Nantucket, Berkshire, and Hampden Counties (p \u3c 0.05). Co-prescriptions and cash payment clusters were localized and nearly identical (p \u3c 0.05). Overlap in PIP and overdose clusters was identified in Cape Cod and Berkshire County. However, we also found contradictory patterns in overdose and PIP hotspots.
CONCLUSIONS: Overdose and PIP hotspots were identified, as well as regions where the two overlapped, and where they diverged. Results indicate that PIP clustering alone does not explain overdose clustering patterns. Our findings can inform public health policy decisions at the local level, which include a focus on PIP and misuse of heroin and fentanyl that aim to curb opioid overdoses
Galaxy Zoo: Dust in Spirals
We investigate the effect of dust on spiral galaxies by measuring the
inclination-dependence of optical colours for 24,276 well-resolved SDSS
galaxies visually classified in Galaxy Zoo. We find clear trends of reddening
with inclination which imply a total extinction from face-on to edge-on of 0.7,
0.6, 0.5 and 0.4 magnitudes for the ugri passbands. We split the sample into
"bulgy" (early-type) and "disky" (late-type) spirals using the SDSS fracdeV (or
f_DeV) parameter and show that the average face-on colour of "bulgy" spirals is
redder than the average edge-on colour of "disky" spirals. This shows that the
observed optical colour of a spiral galaxy is determined almost equally by the
spiral type (via the bulge-disk ratio and stellar populations), and reddening
due to dust. We find that both luminosity and spiral type affect the total
amount of extinction, with "disky" spirals at M_r ~ -21.5 mags having the most
reddening. This decrease of reddening for the most luminous spirals has not
been observed before and may be related to their lower levels of recent star
formation. We compare our results with the latest dust attenuation models of
Tuffs et al. We find that the model reproduces the observed trends reasonably
well but overpredicts the amount of u-band attenuation in edge-on galaxies. We
end by discussing the effects of dust on large galaxy surveys and emphasize
that these effects will become important as we push to higher precision
measurements of galaxy properties and their clustering.Comment: MNRAS in press. 25 pages, 22 figures (including an abstract comparing
GZ classifications with common automated methods for selecting disk/early
type galaxies in SDSS data). v2 corrects typos found in proof
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