A
bstract
A search for pair-produced third generation scalar leptoquarks is presented, using proton-proton collisions at
TeV at the LHC. The data were recorded with the ATLAS detector and correspond ...to an integrated luminosity of 4.7 fb
−1
. Each leptoquark is assumed to decay to a tau lepton and a
b
-quark with a branching fraction equal to 100%. No statistically significant excess above the Standard Model expectation is observed. Third generation leptoquarks are therefore excluded at 95% confidence level for masses less than 534GeV.
We computationally investigate coupling of a nonlinear rotational dissipative element to a sprung circular cylinder allowed to undergo transverse vortex-induced vibration (VIV) in an incompressible ...flow. The dissipative element is a ‘nonlinear energy sink’ (NES), consisting of a mass rotating at fixed radius about the cylinder axis and a linear viscous damper that dissipates energy from the motion of the rotating mass. We consider the Reynolds number range
$20\leqslant Re\leqslant 120$
, with
$Re$
based on cylinder diameter and free-stream velocity, and the cylinder restricted to rectilinear motion transverse to the mean flow. Interaction of this NES with the flow is mediated by the cylinder, whose rectilinear motion is mechanically linked to rotational motion of the NES mass through nonlinear inertial coupling. The rotational NES provides significant ‘passive’ suppression of VIV. Beyond suppression however, the rotational NES gives rise to a range of qualitatively new behaviours not found in transverse VIV of a sprung cylinder without an NES, or one with a ‘rectilinear NES’, considered previously. Specifically, the NES can either stabilize or destabilize the steady, symmetric, motionless-cylinder solution and can induce conditions under which suppression of VIV (and concomitant reduction in lift and drag) is accompanied by a greatly elongated region of attached vorticity in the wake, as well as conditions in which the cylinder motion and flow are temporally chaotic at relatively low
$Re$
.
A general framework for combining ecosystem models Spence, Michael A.; Blanchard, Julia L.; Rossberg, Axel G. ...
Fish and fisheries,
November 2018, 2018-11-00, 20181101, Letnik:
19, Številka:
6
Journal Article
Recenzirano
Odprti dostop
When making predictions about ecosystems, we often have available a number of different ecosystem models that attempt to represent their dynamics in a detailed mechanistic way. Each of these can be ...used as a simulator of large‐scale experiments and make projections about the fate of ecosystems under different scenarios to support the development of appropriate management strategies. However, structural differences, systematic discrepancies and uncertainties lead to different models giving different predictions. This is further complicated by the fact that the models may not be run with the same functional groups, spatial structure or time scale. Rather than simply trying to select a “best” model, or taking some weighted average, it is important to exploit the strengths of each of the models, while learning from the differences between them. To achieve this, we construct a flexible statistical model of the relationships between a collection of mechanistic models and their biases, allowing for structural and parameter uncertainty and for different ways of representing reality. Using this statistical meta‐model, we can combine prior beliefs, model estimates and direct observations using Bayesian methods and make coherent predictions of future outcomes under different scenarios with robust measures of uncertainty. In this study, we take a diverse ensemble of existing North Sea ecosystem models and demonstrate the utility of our framework by applying it to answer the question what would have happened to demersal fish if fishing was to stop.
A
bstract
In several extensions of the Standard Model, the top quark can decay into a bottom quark and a light charged Higgs boson
H
+
,
t
→
bH
+
, in addition to the Standard Model decay
t
→
bW
.... Since
W
bosons decay to the three lepton generations equally, while
H
+
maypredominantlydecayinto
τν
, charged Higgs bosons can be searched for using the violation of lepton universality in top quark decays. The analysis in this paper is based on 4.6 fb
−1
of proton-proton collision data at
TeV collected by the ATLAS experiment at the Large Hadron Collider. Signatures containing leptons (
e
or
μ
) and/or a hadronically decaying
τ
(
τ
had
) are used. Event yield ratios between
e
+
τ
had
and
e
+
μ
, as well as between
μ
+
τ
had
and
μ
+
e
, final states are measured in the data and compared to predictions from simulations. This ratio-based method reduces the impact of systematic uncertainties in the analysis. No significant deviation from the Standard Model predictions is observed. With the assumption that the branching fraction
(
H
+
→
τν
) is 100%, upper limits in the range 3.2%–4.4% can be placed on the branching fraction
(
t
→
bH
+
) for charged Higgs boson masses
m
H
+
in the range 90–140 GeV. After combination with results from a search for charged Higgs bosons in
decays using the
τ
had
+ jets final state, upper limits on
(
t
→
bH
+
) can be set in the range 0.8%–3.4%, for
m
H
+
in the range 90-160 GeV.
Stress in socially subordinate male rats, associated with aggressive attacks by dominant males, was studied in a group-housing
context called the visible burrow system (VBS). It has been established ...that subordinate males have reduced serum testosterone
(T) and higher corticosterone (CORT) relative to dominant and singly housed control males. The relationship of the decreased
circulating T levels in subordinate males to changes in serum LH concentrations has not been evaluated previously. Since decreases
in LH during stress may cause reductions in Leydig cell steroidogenic activity, the present study defined the temporal profiles
of serum LH, T, and CORT in dominant and subordinate males on Days 4, 7, and 14 of a 14-day housing period in the VBS. The
same parameters were followed in serum samples from single-housed control males. Leydig cells express glucocorticoid receptors
and may also be targeted for direct inhibition of steroidogenesis by glucocorticoid. We hypothesize that Leydig cells are
protected from inhibition by CORT at basal concentrations through oxidative inactivation of glucocorticoid by 11β-hydroxysteroid
dehydrogenase (11βHSD). However, Leydig cell steroidogenesis is inhibited when 11βHSD metabolizing capacity is exceeded. Therefore,
11βHSD enzyme activity levels were measured in Leydig cells of VBS-housed males at the same time points. Significant increases
in LH and T relative to control were observed in the dominant animals on Day 4, which were associated with the overt establishment
of behavioral dominance as evidenced by victorious agonistic encounters. Serum LH and T were lower in subordinate males on
Day 7, but T alone was lower on Day 14, suggesting that lowered LH secretion in subordinates may gradually be reversed by
declines in androgen-negative feedback. Serum CORT levels were higher in subordinate males compared to control at all three
time points. In contrast, oxidative 11βHSD activity in Leydig cells of dominant males was higher relative to control and unchanged
in subordinates. These results suggest the following: 1) failure of Leydig cells of subordinate males to compensate for increased
glucocorticoid action during stress, by increasing 11βHSD oxidative activity, potentiates stress-mediated reductions in T
secretion; and 2) an inhibition of the reproductive axis in subordinate males at the level of the pituitary.
Lifestyle interventions are the first-line treatment for obesity, but participant weight loss is typically low.
We evaluated the efficacy of an alternative lifestyle intervention Healthy Weight for ...Living (HWL) compared with a modified Diabetes Prevention Program (m-DPP). HWL was based on a revised health behavior change model emphasizing hunger management and the development of healthy food preferences. m-DPP was a standard Diabetes Prevention Program implemented with counselor time matched to HWL. Participants were adult dependents of military personnel and had overweight or obesity.
Participants were randomly assigned to HWL (n = 121) or m-DPP (n = 117), delivered primarily by group videoconference with additional midweek emails. The primary outcome was 12-mo weight change. Secondary outcomes included 6-mo changes in cardiometabolic risk factors and diet. Intention-to-treat (ITT) and complete case (CC) analyses were performed using linear mixed models.
Retention did not differ between groups (72% and 66% for HWL and m-DPP at 12 mo, respectively; P = 0.30). Mean ± SE adjusted 12-mo weight loss in the ITT cohort was 7.46 ± 0.85 kg for HWL and 7.32 ± 0.87 kg for m-DPP (P = 0.91); in the CC cohort, it was 7.83 ± 0.82 kg for HWL and 6.86 ± 0.88 kg for m-DPP (P = 0.43). Thirty-eight percent of HWL and 30% of m-DPP completers achieved ≥10% weight loss (P = 0.32). Improvements in systolic blood pressure, LDL cholesterol, triglycerides, fasting glucose, general health, sleep, and mood were similar across groups; improvements in diastolic blood pressure were greater in m-DPP. Adjusted group mean reductions in energy intake were not significantly different between groups, but HWL participants were more adherent to their dietary prescription for lower glycemic index and high fiber and protein (P = 0.05 to <0.001 for ITT).
HWL and m-DPP showed equivalent and clinically impactful mean weight loss with cardiometabolic benefits. These results identify an alternative approach for behavioral treatment of overweight and obesity. This trial was registered at clinicaltrials.gov as NCT02348853.
The peroxisome proliferator-activated receptors (PPARs) are nuclear hormone receptors that regulate glucose and lipid homeostasis. The PPARγ subtype plays a central role in the regulation of ...adipogenesis and is the molecular target for the 2,4-thiazolidinedione class of antidiabetic drugs. Structural studies have revealed that agonist ligands activate the PPARs through direct interactions with the C-terminal region of the ligand-binding domain, which includes the activation function 2 helix. GW0072 was identified as a high-affinity PPARγ ligand that was a weak partial agonist of PPARγ transactivation. X-ray crystallography revealed that GW0072 occupied the ligand-binding pocket by using different epitopes than the known PPAR agonists and did not interact with the activation function 2 helix. In cell culture, GW0072 was a potent antagonist of adipocyte differentiation. These results establish an approach to the design of PPAR ligands with modified biological activities.
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