1,076 research outputs found
Modelling the effects of sediment compaction on salt marsh reconstructions of recent sea-level rise
This paper quantifies the potential influence of sediment compaction on the magnitude of nineteenth and twentieth century sea-level rise, as reconstructed from salt marsh sediments. We firstly develop a database of the physical and compression properties of low energy intertidal and salt marsh sediments. Key compression parameters are controlled by organic content (loss on ignition), though compressibility is modulated by local-scale processes, notably the potential for desiccation of sediments. Using this database and standard geotechnical theory, we use a numerical modelling approach to generate and subsequently ‘decompact’ a range of idealised intertidal stratigraphies. We find that compression can significantly contribute to reconstructed accelerations in recent sea level, notably in transgressive stratigraphies. The magnitude of this effect can be sufficient to add between 0.1 and 0.4 mm yr−1 of local sea-level rise, depending on the thickness of the stratigraphic column. In contrast, records from shallow (<0.5 m) uniform-lithology stratigraphies, or shallow near-surface salt marsh deposits in regressive successions, experience negligible compaction. Spatial variations in compression could be interpreted as ‘sea-level fingerprints’ that might, in turn, be wrongly attributed to oceanic or cryospheric processes. However, consideration of existing sea-level records suggests that this is not the case and that compaction cannot be invoked as the sole cause of recent accelerations in sea level inferred from salt marsh sediments
Eimeria species occurrence varies between geographic regions and poultry production systems and may influence parasite genetic diversity
Coccidiosis is one of the biggest challenges faced by the global poultry industry. Recent studies have highlighted the ubiquitous distribution of all Eimeria species which can cause this disease in chickens, but intriguingly revealed a regional divide in genetic diversity and population structure for at least one species, Eimeria tenella. The drivers associated with such distinct geographic variation are unclear, but may impact on the occurrence and extent of resistance to anticoccidial drugs and future subunit vaccines. India is one of the largest poultry producers in the world and includes a transition between E. tenella populations defined by high and low genetic diversity. The aim of this study was to identify risk factors associated with the prevalence of Eimeria species defined by high and low pathogenicity in northern and southern states of India, and seek to understand factors which vary between the regions as possible drivers for differential genetic variation. Faecal samples and data relating to farm characteristics and management were collected from 107 farms from northern India and 133 farms from southern India. Faecal samples were analysed using microscopy and PCR to identify Eimeria occurrence. Multiple correspondence analysis was applied to transform correlated putative risk factors into a smaller number of synthetic uncorrelated factors. Hierarchical cluster analysis was used to identify poultry farm typologies, revealing three distinct clusters in the studied regions. The association between clusters and presence of Eimeria species was assessed by logistic regression. The study found that large-scale broiler farms in the north were at greatest risk of harbouring any Eimeria species and a larger proportion of such farms were positive for E. necatrix, the most pathogenic species. Comparison revealed a more even distribution for E. tenella across production systems in south India, but with a lower overall occurrence. Such a polarised region- and system-specific distribution may contribute to the different levels of genetic diversity observed previously in India and may influence parasite population structure across much of Asia and Africa. The findings of the study can be used to prioritise target farms to launch and optimise appropriate anticoccidial strategies for long-term control
The Landau Pole and decays in the 331 bilepton model
We calculate the decay widths and branching ratios of the extra neutral boson
predicted by the 331 bilepton model in the framework of two
different particle contents. These calculations are performed taken into
account oblique radiative corrections, and Flavor Changing Neutral Currents
(FCNC) under the ansatz of Matsuda as a texture for the quark mass matrices.
Contributions of the order of are obtained in the branching
ratios, and partial widths about one order of magnitude bigger in relation with
other non- and bilepton models are also obtained. A Landau-like pole arise at
3.5 TeV considering the full particle content of the minimal model (MM), where
the exotic sector is considered as a degenerated spectrum at 3 TeV scale. The
Landau pole problem can be avoid at the TeV scales if a new leptonic content
running below the threshold at TeV is implemented as suggested by other
authors.Comment: 20 pages, 5 figures, LaTeX2
Does routine uniportal thoracoscopy during rib fixation identify more injuries and impact outcomes?
Background: Flail chest and severely displaced rib fractures due to blunt trauma can be associated with intrathoracic injuries. At our institution, two thoracic surgeons perform all surgical stabilization of rib fractures (SSRF): one performs routine uniportal thoracoscopy (R-VATS) at the time of SSRF and the other for only select cases (S-VATS). In this pilot study, we hypothesized that R-VATS at the time of SSRF identifies and addresses intrathoracic injuries not seen on imaging and may impact patient outcomes. Methods: A retrospective review of all patients who underwent SSRF from 2013-2019 at our institution was performed for severely displaced rib fractures or flail chest. Data collected included demographics, imaging results, treatment strategy, and operative findings. Results: Ninety-nine patients underwent SSRF. Uniportal thoracoscopy was performed on 69% of these patients. When thoracoscopy was performed, 31 additional injuries were identified. R-VATS identified 23 additional intrathoracic findings at time of thoracoscopy not seen on CT scan compared to 8 findings in the S-VATS group (P=0.367). At 3 months follow-up, one empyema and one diaphragmatic hernia required reoperation-neither of which underwent thoracoscopy at time of SSRF. There were no differences in LOS, operative times, and overall mortality between the SSRF/thoracoscopy and SSRF only groups. Conclusions: R-VATS at the time of SSRF did not identify a statistically significant greater number of occult intrathoracic injuries compared to S-VATS. R-VATS was not associated with increased operative time, LOS, and mortality. Further study is needed to determine if there is benefit to R-VATS in patients meeting requirements for rib fracture repair
Novel sources of Flavor Changed Neutral Currents in the model
Sources of Flavor Changed Neutral Currents (FCNC) naturally emerge from a
well motivated framework called 3-3-1 with right-handed neutrinos model,
for short, mediated by an extra neutral gauge boson .
Following previous works we calculate these sources and in addition we derive
new ones coming from CP-even and -odd neutral scalars which appear due to their
non-diagonal interactions with the physical standard quarks. Furthermore we
show that bounds related to the neutral mesons systems and may be significantly strengthened in the presence of these new
interactions allowing us to infer stronger constraints on the parameter space
of the model.Comment: Published version. 10 pages, 6 figure
Responding to a Community's Concern: A Comparison of Breast Cancer Characteristics and Initial Treatment in Three Selected North Carolina Counties
BACKGROUND A 2007 national report identified North Carolina's Edgecombe County as having among the highest breast cancer incidence and mortality rates nationally, motivating the initiation of a task force and other local efforts to address the problem. The goal of this study is to examine county breast cancer characteristics before and after the report, including whether geographic variation may mask racial disparities in this majority African American community. METHOD With guidance from community partners, breast cancer cases from 2000 to 2012 in Edgecombe, Nash, and Orange Counties (N = 2,641) were obtained from the North Carolina Central Cancer Registry. Bivariate and trend analyses of tumor and treatment characteristics were examined by county and race. RESULTS Women in Edgecombe and Nash Counties were diagnosed with more advanced stage, higher grade tumors. African Americans in Edgecombe and Nash Counties were diagnosed with advanced disease more often than African Americans in Orange County. Average time-to-treatment was well within guideline recommendations. Incidence and mortality rates appear to have declined, with variation in measures of racial differences over time. LIMITATIONS Changes in coding standards across the observation period required reliance on coarse measures that may partially mute useful findings. CONCLUSIONS Racial disparities remain a concern in North Carolina; however, they appear to be less profound than in the 2007 national report. The portentous statistics in the report represent an all-time high, after which some, but not all, measures reflect positive change amidst ongoing local efforts to improve breast cancer knowledge and care
The 3-3-1 model with S_4 flavor symmetry
We construct a 3-3-1 model based on family symmetry S_4 responsible for the
neutrino and quark masses. The tribimaximal neutrino mixing and the diagonal
quark mixing have been obtained. The new lepton charge \mathcal{L} related to
the ordinary lepton charge L and a SU(3) charge by L=2/\sqrt{3} T_8+\mathcal{L}
and the lepton parity P_l=(-)^L known as a residual symmetry of L have been
introduced which provide insights in this kind of model. The expected vacuum
alignments resulting in potential minimization can origin from appropriate
violation terms of S_4 and \mathcal{L}. The smallness of seesaw contributions
can be explained from the existence of such terms too. If P_l is not broken by
the vacuum values of the scalar fields, there is no mixing between the exotic
and the ordinary quarks at the tree level.Comment: 20 pages, revised versio
A measurement of the tau mass and the first CPT test with tau leptons
We measure the mass of the tau lepton to be 1775.1+-1.6(stat)+-1.0(syst.) MeV
using tau pairs from Z0 decays. To test CPT invariance we compare the masses of
the positively and negatively charged tau leptons. The relative mass difference
is found to be smaller than 3.0 10^-3 at the 90% confidence level.Comment: 10 pages, 4 figures, Submitted to Phys. Letts.
- …