2,183 research outputs found
Observing The Hidden Sector
We study the effects of renormalization due to hidden-sector dynamics on
observable soft supersymmetry-breaking parameters in the minimal supersymmetric
extension of the Standard Model (MSSM), under various hypotheses about their
universality at a high input scale. We show that hidden-sector renormalization
effects may induce the spurious appearance of unification of the scalar masses
at some lower scale, as in mirage unification scenarios. We demonstrate in
simple two-parameter models of the hidden-sector dynamics that the parameters
may in principle be extracted from experimental measurements, rendering the
hidden sector observable. We also discuss the ingredients that would be
necessary to carry this programme out in practice.Comment: 38 pages, 13 figures, uses UApreprint.cls and subfigure.sty
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Triviality and the (Supersymmetric) See-Saw
For the D=5 Majorana neutrino mass operator to have a see-saw ultraviolet
completion that is viable up to the Planck scale, the see-saw scale is bounded
above due to triviality limits on the see-saw couplings. For supersymmetric
see-saw models, with realistic neutrino mass textures, we compare constraints
on the see-saw scale from triviality bounds, with those arising from
experimental limits on induced charged-lepton flavour violation, for both the
CMSSM and for models with split supersymmetry.Comment: 27 pages, 7 figures, references adde
Preferences for endovascular (EVAR) or open surgical repair among patients with abdominal aortic aneurysms under surveillance
ObjectivesThere is no evidence about patient preferences for treatment of abdominal aortic aneurysms (AAA) by endovascular aneurysm repair (EVAR) or open surgical repair (OSR). This study examined patient preferences for elective future aneurysm repair and factors that may influence such preferences.MethodsPatients with small AAAs under ultrasound scan surveillance at two United Kingdom (UK) hospitals participated in a semi-structured telephone interview. Features of the two techniques were assessed with regard to their influence on the preferences of participants for EVAR or OSR, using a Likert scale. In addition, participants ranked the relative importance of 14 features against each other.ResultsFifty-six out of 100 eligible participants (56%) completed the semi-structured telephone interview. Of those, 84% (47 patients) said they would prefer a future EVAR repair. Patients who expressed a preference for OSR were significantly younger. Risks of major organ failure and death were most commonly judged as important features in influencing patient preference (Likert scale score 5/5). Risk of death was also most frequently ranked above all other features. Postoperative morbidity and mortality were regarded by patients as more important than the need for surveillance and risk of long-term problems with EVAR. Type of incision and radiation exposure were both given low Likert scale scores of 1/5, and the risk of sexual dysfunction was most frequently ranked as the least important feature of either operation, out of 14 other features.ConclusionWhen presented with detailed information about EVAR and OSR, most patients with small aneurysms would prefer EVAR
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Beyond Crossing Fibers: Bootstrap Probabilistic Tractography Using Complex Subvoxel Fiber Geometries
Diffusion magnetic resonance imaging fiber tractography is a powerful tool for investigating human white matter connectivity in vivo. However, it is prone to false positive and false negative results, making interpretation of the tractography result difficult. Optimal tractography must begin with an accurate description of the subvoxel white matter fiber structure, includes quantification of the uncertainty in the fiber directions obtained, and quantifies the confidence in each reconstructed fiber tract. This paper presents a novel and comprehensive pipeline for fiber tractography that meets the above requirements. The subvoxel fiber geometry is described in detail using a technique that allows not only for straight crossing fibers but for fibers that curve and splay. This technique is repeatedly performed within a residual bootstrap statistical process in order to efficiently quantify the uncertainty in the subvoxel geometries obtained. A robust connectivity index is defined to quantify the confidence in the reconstructed connections. The tractography pipeline is demonstrated in the human brain
Food and earth systems: Priorities for climate change adaptation and mitigation for agriculture and food systems
Human activities and their relation with land, through agriculture and forestry, are significantly impacting Earth system functioning. Specifically, agriculture has increasingly become a key sector for adaptation and mitigation initiatives that address climate change and help ensure food security for a growing global population. Climate change and agricultural outcomes influence our ability to reach targets for at least seven of the 17 Sustainable Development Goals. By 2015, 103 nations had committed themselves to reduce greenhouse gas emissions from agriculture, while 102 countries had prioritized agriculture in their adaptation agenda. Adaptation and mitigation actions within agriculture still receive insufficient support across scales, from local to international level. This paper reviews a series of climate change adaptation and mitigation options that can support increased production, production efficiency and greater food security for 9 billion people by 2050. Climate-smart agriculture can help foster synergies between productivity, adaptation, and mitigation, although trade-offs may be equally apparent. This study highlights the importance of identifying and exploiting those synergies in the context of Nationally Determined Contributions. Finally, the paper points out that keeping global warming to 2 °C above pre-industrial levels by 2100 requires going beyond the agriculture sector and exploring possibilities with respect to reduced emissions from deforestation, food loss, and waste, as well as from rethinking human diets
Prevention of an additional surgery for regional lymphadenectomy in melanoma: rapid intraoperative immunostaining of sentinel lymph node imprint smears
BACKGROUND: Sentinel lymph node (SLN) biopsy is performed at many institutions and is considered a standard of care in the management of cutaneous melanoma. The discriminatory immunostaining pattern with the 'MCW Melanoma Cocktail' (a mixture of MART-1 {1:500}, Melan- A {1:100}, and Tyrosinase {1:50} monoclonal antibodies) allows intraoperative immunocytochemical evaluation of imprint smears of SLNs for melanoma metastases. Cohesive cells of benign capsular melanocytic nevi that were also immunoreactive with the cocktail do not exfoliate easily for imprint smear detection. METHODS: We prospectively evaluated 73 lymph nodes (70 SLN & 3 non-SLN) from 41 cases (mean 1.8, 1 to 4 SLNs/case) of cutaneous melanoma using a rapid 17-minute immunostaining previously published protocol. The results were compared with permanent sections also immunostained with 'the cocktail'. RESULTS: 19.5%, 8/41 cases (12%, 9/73 lymph nodes) were positive for melanoma metastases on permanent sections immunostained with the 'MCW melanoma cocktail'. Melanoma metastases in 87.5% (7/8) of these cases were also detected in rapidly immunostained imprint smears, with 100% specificity and 90% sensitivity. None of the 7 SLNs from 7 cases with capsular nevi showed false positive results. CONCLUSION: Melanoma metastases could be detected in imprint smears immunostained with 'MCW Melanoma Cocktail' utilizing a rapid intraoperative protocol. The cohesive cells of the capsular nevi do not readily exfoliate and do not lead to false positive interpretation. In a majority of positive cases, a regional lymphadenectomy could have been completed during the same surgery for SLN biopsy and wide excision of primary melanoma site, potentially eliminating the need for an additional surgery
Correcting for T1 bias in Magnetization Transfer Saturation (MTsat) Maps Using Sparse-MP2RAGE
Purpose: Magnetization transfer saturation (MTsat) mapping is commonly used
to examine the macromolecular content of brain tissue. This study compared
variable flip angle (VFA) T1 mapping against compressed sensing (cs)MP2RAGE T1
mapping for accelerating MTsat imaging. Methods: VFA, MP2RAGE and csMP2RAGE
were compared against inversion recovery (IR) T1 in a phantom at 3 Tesla. The
same 1 mm VFA, MP2RAGE and csMP2RAGE protocols were acquired in four healthy
subjects to compare the resulting T1 and MTsat. Bloch-McConnell simulations
were used to investigate differences between the phantom and in vivo T1
results. Finally, ten healthy controls were imaged twice with the csMP2RAGE
MTsat protocol to quantify repeatability. Results: The MP2RAGE and csMP2RAGE
protocols were 13.7% and 32.4% faster than the VFA protocol, respectively. All
approaches provided accurate T1 values (<5% difference) in the phantom, but the
accuracy of the T1 times was more impacted by differences in T2 for VFA than
for MP2RAGE. In vivo, VFA generated longer T1 times than MP2RAGE and csMP2RAGE.
Simulations suggest that the bias in the T1 values between VFA and IR-based
approaches (MP2RAGE and IR) could be explained by the MT-effects from the
inversion pulse. In the test-retest experiment, we found that the csMP2RAGE has
a minimum detectable change of 3% for T1 mapping and 7.9% for MTsat imaging.
Conclusions: We demonstrated that csMP2RAGE can be used in place of VFA T1
mapping in an MTsat protocol. Furthermore, a shorter scan time and high
repeatability can be achieved using the csMP2RAGE sequence.Comment: 23 pages, 7 figures, 2 table
Evidence for a Long-period Planet Orbiting Epsilon Eridani
High precision radial velocity (RV) measurements spanning the years
1980.8--2000.0 are presented for the nearby (3.22 pc) K2 V star Eri.
These data, which represent a combination of six independent data sets taken
with four different telescopes, show convincing variations with a period of
7 yrs. A least squares orbital solution using robust estimation
yields orbital parameters of period, = 6.9 yrs, velocity -amplitude
19 {\ms}, eccentricity 0.6, projected companion mass sin = 0.86
, and semi-major axis 3.3 AU. Ca II H&K S-index
measurements spanning the same time interval show significant variations with
periods of 3 and 20 yrs, yet none at the RV period. If magnetic activity were
responsible for the RV variations then it produces a significantly different
period than is seen in the Ca II data. Given the lack of Ca II variation with
the same period as that found in the RV measurements, the long-lived and
coherent nature of these variations, and the high eccentricity of the implied
orbit, Keplerian motion due to a planetary companion seems to be the most
likely explanation for the observed RV variations. The wide angular separation
of the planet from the star (approximately 1 arc-second) and the long orbital
period make this planet a prime candidate for both direct imaging and
space-based astrometric measurements.Comment: To appear in Astrophysical Journal Letters. 9 pages, 2 figure
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