Origins of Hidden Sector Dark Matter I: Cosmology

We present a systematic cosmological study of a universe in which the visible sector is coupled, albeit very weakly, to a hidden sector comprised of its own set of particles and interactions. Assuming that dark matter (DM) resides in the hidden sector and is charged under a stabilizing symmetry shared by both sectors, we determine all possible origins of weak-scale DM allowed within this broad framework. We show that DM can arise only through a handful of mechanisms, lending particular focus to Freeze-Out and Decay and Freeze-In, as well as their variations involving late time re-annihilations of DM and DM particle anti-particle asymmetries. Much like standard Freeze-Out, where the abundance of DM depends only on the annihilation cross-section of the DM particle, these mechanisms depend only on a very small subset of physical parameters, many of which may be measured directly at the LHC. In particular, we show that each DM production mechanism is associated with a distinctive window in lifetimes and cross-sections for particles which may be produced in the near future. We evaluate prospects for employing the LHC to definitively reconstruct the origin of DM in a companion paper.Comment: 32 pages, 19 figures; v2: references added, published versio

Experiences of adolescents and young adults with ADHD in Hong Kong: treatment services and clinical management

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Continuation of dabigatran therapy in "real-world" practice in Hong Kong

Background: Dabigatran, an oral direct thrombin inhibitor, possesses several advantages over warfarin that can in principle simplify the management of stroke prevention in atrial fibrillation (AF). Nonetheless it remains unclear whether these advantages can translate to clinical practice and encourage long-term therapy. The objective was to describe long-term dabigatran therapy for stroke prevention in AF and to identify risk factors for discontinuation of therapy. Methods and Results: We studied 467 consecutive Chinese patients (72±11 years, male: 53.8%) with a mean CHA2DS2-VASc score of 3.6 prescribed dabigatran for stroke prevention in AF from March 2010 to September 2013. Over a mean follow-up of 16 months, 101 patients (21.6%) permanently discontinued dabigatran. The mean time-to-discontinuation was 8 months. The most common reason for discontinuation was dyspepsia (30.7%), followed by other adverse events (17.8%) such as minor bleeding (8.9%), major gastrointestinal bleeding (7.9%), and intracranial hemorrhage (1%). Other reasons included dosing frequency (5.9%), fear of side effects (4.0%), lack of laboratory monitoring (1.0%), and cost (1.0%). Multivariable analysis revealed that low baseline estimated glomerular filtration rate (p = 0.02), absence of hypertension (p= 0.01), and prior use of a proton-pump inhibitor (p = 0.02) and H2-receptor blocker (p = 0.01) were independent predictors of drug discontinuation. In addition, there were altogether 9 ischemic strokes (1.5%/years), 3 intracranial hemorrhages (0.5%/year), and 24 major gastrointestinal bleedings (4.1%/year). Conclusion: Dabigatran discontinuation is very common amongst Chinese AF patients. This reveals a management gap in the prevention of stroke in AF. © 2014 Ho et al.published_or_final_versio

On BCFW shifts of integrands and integrals

In this article a first step is made towards the extension of Britto-Cachazo-Feng-Witten (BCFW) tree level on-shell recursion relations to integrands and integrals of scattering amplitudes to arbitrary loop order. Surprisingly, it is shown that the large BCFW shift limit of the integrands has the same structure as the corresponding tree level amplitude in any minimally coupled Yang-Mills theory in four or more dimensions. This implies that these integrands can be reconstructed from a subset of their `single cuts'. The main tool is powercounting Feynman graphs in a special lightcone gauge choice employed earlier at tree level by Arkani-Hamed and Kaplan. The relation between shifts of integrands and shifts of its integrals is investigated explicitly at one loop. Two particular sources of discrepancy between the integral and integrand are identified related to UV and IR divergences. This is cross-checked with known results for helicity equal amplitudes at one loop. The nature of the on-shell residue at each of the single-cut singularities of the integrand is commented upon. Several natural conjectures and opportunities for further research present themselves.Comment: 43 pages, 6 figures, v2: minor improvement in exposition, typos fixed, bibliography update

Overexpression of Forkhead Box Protein M1 (FOXM1) in Ovarian Cancer Correlates with Poor Patient Survival and Contributes to Paclitaxel Resistance

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Burden of upper gastrointestinal symptoms in patients prescribed dabigatran for stroke prevention

BACKGROUND: Dabigatran, a non-vitamin K antagonist oral anticoagulant, has been shown to prevent stroke in patients with non-valvular atrial fibrillation. Nonetheless, studies show that 10%-30% of those prescribed dabigatran experience dyspepsia that may eventually lead to discontinuation of therapy and loss of clinical benefit. AIM: To evaluate the gastrointestinal tolerability of dabigatran utilizing a validated questionnaire, as well as determining subsequent non-compliance and drug discontinuation. METHOD: This is an observational study. All patients were assessed by a validated questionnaire, Hong Kong dyspepsia index, prior to drug prescription and again 4 weeks later. RESULTS: In this study, 115 patients with non-valvular atrial fibrillation (mean age: 74.6 ± 11.4 years; mean CHA2DS2-VASc score was 3.39 ± 1.59) were prescribed dabigatran. At baseline, the mean Hong Kong dyspepsia index was 12.9 ± 1.6 and nine patients had significant dyspepsia (Hong Kong dyspepsia index ⩾ 16). After 4 weeks, the mean Hong Kong dyspepsia index was similar at 12.6 ± 1.9 (p = 0.23). There was no change in Hong Kong dyspepsia index after initiation of dabigatran in 59 (51.3%) patients, and improvement in 37 (32.2%). Only 19 (16.5%) patients had worsening of Hong Kong dyspepsia index, and among these 19 patients, only 1 patient (0.9%) discontinued dabigatran due to significant dyspepsia. CONCLUSION: Worsening of dyspepsia with dabigatran 110 mg twice daily was uncommon with correct drug administration and clear instructions provided. Systematic assessment of dyspeptic symptoms using a validated questionnaire (i.e. Hong Kong dyspepsia index) before and after treatment initiation allows a more objective comparison of dyspeptic symptoms

Binary orbits as the driver of γ-ray emission and mass ejection in classical novae

Classical novae are the most common astrophysical thermonuclear explosions, occurring on the surfaces of white dwarf stars accreting gas from companions in binary star systems. Novae typically expel �10,000 solar masses of material at velocities exceeding 1,000 km/s. However, the mechanism of mass ejection in novae is poorly understood, and could be dominated by the impulsive flash of the thermonuclear runaway, prolonged optically thick winds, or binary interaction with the nova envelope. Classical novae are now routinely detected in GeV gamma-rays, suggesting that relativistic particles are accelerated by strong shocks in nova ejecta. Here we present high-resolution imaging of the gamma-ray-emitting nova V959 Mon at radio wavelengths, showing that its ejecta were shaped by binary motion: some gas was expelled rapidly along the poles as a wind from the white dwarf, while denser material drifted out along the equatorial plane, propelled by orbital motion. At the interface between the equatorial and polar regions, we observe synchrotron emission indicative of shocks and relativistic particle acceleration, thereby pinpointing the location of gamma-ray production. Binary shaping of the nova ejecta and associated internal shocks are expected to be widespread among novae, explaining why many novae are gamma-ray emitters

Electroweak Baryogenesis and Dark Matter with an approximate R-symmetry

It is well known that R-symmetric models dramatically alleviate the SUSY flavor and CP problems. We study particular modifications of existing R-symmetric models which share the solution to the above problems, and have interesting consequences for electroweak baryogenesis and the Dark Matter (DM) content of the universe. In particular, we find that it is naturally possible to have a strongly first-order electroweak phase transition while simultaneously relaxing the tension with EDM experiments. The R-symmetry (and its small breaking) implies that the gauginos (and the neutralino LSP) are pseudo-Dirac fermions, which is relevant for both baryogenesis and DM. The singlet superpartner of the U(1)_Y pseudo-Dirac gaugino plays a prominent role in making the electroweak phase transition strongly first-order. The pseudo-Dirac nature of the LSP allows it to behave similarly to a Dirac particle during freeze-out, but like a Majorana particle for annihilation today and in scattering against nuclei, thus being consistent with current constraints. Assuming a standard cosmology, it is possible to simultaneously have a strongly first-order phase transition conducive to baryogenesis and have the LSP provide the full DM relic abundance, in part of the allowed parameter space. However, other possibilities for DM also exist, which are discussed. It is expected that upcoming direct DM searches as well as neutrino signals from DM annihilation in the Sun will be sensitive to this class of models. Interesting collider and Gravity-wave signals are also briefly discussed.Comment: 50 pages, 10 figure

ACE (Angiotensin-Converting Enzyme) Inhibitors/Angiotensin Receptor Blockers Are Associated With Lower Colorectal Cancer Risk: A Territory-Wide Study With Propensity Score Analysis

Whether ACE (angiotensin-converting enzyme) inhibitors and angiotensin receptor blockers modify colorectal cancer risk remains controversial. We aimed to determine association between their use and colorectal cancer risk after a negative baseline colonoscopy. This is a territory-wide retrospective cohort study recruiting patients aged ≥40 who had undergone colonoscopy between 2005 and 2013. Exclusion criteria included colorectal cancer detected 3years (adjusted hazard ratio, 1.18 [95% CI, 0.88-1.57]); every single year increase in the drug use was associated with 5% reduction in adjusted hazard ratio risk. ACE inhibitors/angiotensin receptor blocker were associated with a lower colorectal cancer risk in a duration-response manner

A Study of D0 --> K0(S) K0(S) X Decay Channels

Using data from the FOCUS experiment (FNAL-E831), we report on the decay of $D^0$ mesons into final states containing more than one $K^0_S$. We present evidence for two Cabibbo favored decay modes, $D^0\to K^0_SK^0_S K^- \pi^+$ and $D^0\to K^0_SK^0_S K^+ \pi^-$, and measure their combined branching fraction relative to $D^0\to \bar{K} ^0\pi^+\pi^-$ to be $\frac{\Gamma(D^0\to K^0_SK^0_SK^{\pm}\pi^{\mp})}{\Gamma(D^0\to \bar{K} ^0\pi^+\pi^-)}$ = 0.0106 $\pm$ 0.0019 $\pm$ 0.0010. Further, we report new measurements of $\frac{\Gamma(D^0\to K^0_SK^0_SK^0_S)}{\Gamma(D^0\to \bar{K} ^0\pi^+\pi^-)}$ = 0.0179 $\pm$ 0.0027 $\pm$ 0.0026, $\frac{\Gamma(D^0\to K^0\bar{K} ^0)}{\Gamma(D^0\to \bar{K} ^0\pi^+\pi^-)}$ = 0.0144 $\pm$ 0.0032 $\pm$ 0.0016, and $\frac{\Gamma(D^0\to K^0_SK^0_S\pi^+\pi^-)}{\Gamma(D^0\to \bar{K} ^0\pi^+\pi^-)}$ = 0.0208 $\pm$ 0.0035 $\pm$ 0.0021 where the first error is statistical and the second is systematic.Comment: 11 pages, 3 figures, typos correcte