A perturbative approach to BB decays into two π\pi mesons

The modified perturbative approach in which transverse degrees of freedom as well as Sudakov suppressions are taken into account, is applied to $B$ decays into two $\pi$ mesons. The influence of various model parameters (CKM matrix elements, $B$ decay constant, mesonic wave functions) on the results as well as short distance corrections to the weak Hamiltonian are discussed in some detail. The perturbative contributions to the $B$ decays yield branching ratios of the order of $10^{-7}\;-\;10^{-6}$ which values are well below the upper limit for the $\bar{B}^0\to\pi^+\pi^-$ branching ratio as measured by CLEO.Comment: 26 pages, RevTex, 6 figures appended (compressed and uuencode using 'uufiles'

Digital Cognitive Behavioral Therapy for Insomnia in Women With Chronic Migraines

Objective/Background: Insomnia commonly co-occurs with chronic migraines (CM). Non-pharmacological treatments for insomnia in CM patients remain understudied. This is a proof-of-concept study, which aims to evaluate the feasibility, acceptability, and preliminary efficacy of a digital cognitive behavioral therapy for insomnia (dCBT-I) for individuals with CM and insomnia (CM-I) in the United States. Methods: We recruited 42 females with CM-I symptoms from a U.S.-based observational cohort and from the general population via advertisements. Within a multiple baseline design, participants were randomized to receive dCBT-I after 2, 4, or 6 weeks of completing baseline sleep diaries. DCBT-I was scrutinized against benchmarks for completion rates (≥90% to complete dCBT-I), acceptability (≥80% to find dCBT-I acceptable), and posttreatment changes in insomnia symptoms (≥50% indicating a clinically relevant improvement in their insomnia symptoms). As a secondary measure, we also reported percentage of individuals reverting to episodic migraines. Results: Out of 42 randomized, 35 (83.3%) completed dCBT-I within the 12 weeks provided. Of these completers, 33 (94.3%) reported being satisfied (n = 16) or very satisfied (n = 17) with treatment. Additionally, 65.7% of completers responded to treatment as per universally accepted criteria for insomnia. Lastly, 34% of completers reverted from CM to episodic migraine. Conclusion: This study provides evidence for the feasibility and acceptability of dCBT-I in patients with CM-I complaints. Effects of improving insomnia and migraines were suggested. These results indicate that a randomized controlled trial is needed to determine the efficacy of dCBT-I in CM patients

Formation of two-dimensional weak localization in conducting Langmuir-Blodgett films

We report the magnetotransport properties up to 7 T in the organic highly conducting Langmuir-Blodgett(LB) films formed by a molecular association of the electroactive donor molecule bis(ethylendioxy)tetrathiafulvalene (BEDO-TTF) and stearic acid CH$_3$(CH$_2$)$_{16}$COOH. We show the logarithmic decrease of dc conductivity and the negative transverse magnetoresistance at low temperature. They are interpreted in the weak localization of two-dimensional (2D) electronic system based on the homogeneous conducting layer with the molecular size thickness of BEDO-TTF. The electronic length with phase memory is given at the mesoscopic scale, which provides for the first time evidence of the 2D coherent charge transport in the conducting LB films.Comment: 5 pages, 1 Table and 5 figure

Family Unification from Universality

A direct consequence of the occurrence of fermion families is the invariance of currents under certain groups of (universality) transformations. We show how these universality groups can themselves be used to find and study grand family unification models. Identifying two independent - weak and strong - universality groups and assuming that the grand unification group is SU(8N), its subgroup respecting either weak or strong universality is shown to be G = SU(2)xU(1)xSU(3). The fundamental representation of SU(8N) decomposes as N families of leptons and quarks. In the G-invariant limit, all fermions are left-handed. A mechanism for generating the correct number of right-handed fermions with the correct couplings so as to give pure vector colour and electromagnetic currents is exhibited. Universality is shown to result most naturally from a preonic structure of fermions. In such a preonic picture there are no ultraheavy gauge bosons and no anomaly or hierarchy problem.Comment: 30 page

Perturbative QCD Analysis of BB Meson Decays

Resummation of large QCD radiative corrections, including leading and next-to-leading logarithms, in pion electromagnetic form factor is reviewed. Similar formalism is applied to exclusive processes involving heavy mesons, and leads to Sudakov suppression for the semi-leptonic decay $B\to\pi l\nu$. It is found that, with the inclusion of Sudakov effects, perturbative QCD analysis of this decay is possible for the energy fraction of the pion above 0.3. By combining predictions from the soft pion theorems, we estimate that the upper limit of the KM matrix element $|V_{ub}|$ is roughly 0.003.Comment: 26 pages in latex, figures are available for reques

Hall Effect and Resistivity in High-Tc Superconductors: The Conserving Approximation

The Hall coefficient (R_H) of high-Tc cuprates in the normal state shows the striking non-Fermi liquid behavior: R_H follows a Curie-Weiss type temperature dependence, and |R_H|>>1/|ne| at low temperatures in the under-doped compounds. Moreover, R_H is positive for hole-doped compounds and is negative for electron-doped ones, although each of them has a similar hole-like Fermi surface. In this paper, we give the explanation of this long-standing problem from the standpoint of the nearly antiferromagnetic (AF) Fermi liquid. We consider seriously the vertex corrections for the current which are indispensable to satisfy the conservation laws, which are violated within the conventional Boltzmann transport approximation. The obtained total current J_k takes an enhanced value and is no more perpendicular to the Fermi surface due to the strong AF fluctuations. By virtue of this mechanism, the anomalous behavior of R_H in high-Tc cuprates is neutrally explained. We find that both the temperature and the (electron, or hole) doping dependences of R_H in high-T_c cuprates are reproduced well by numerical calculations based on the fluctuation-exchange (FLEX) approximation, applied to the single-band Hubbard model. We also discuss the temperature dependence of R_H in other nearly AF metals, e.g., V_2O_3, kappa-BEDT-TTF organic superconductors, and heavy fermion systems close to the AF phase boundary.Comment: 19 pages, to appear in Phys. Rev. B, No.59, Vol.22, 199

A High Statistics Search for Ultra-High Energy Gamma-Ray Emission from Cygnus X-3 and Hercules X-1

We have carried out a high statistics (2 Billion events) search for ultra-high energy gamma-ray emission from the X-ray binary sources Cygnus X-3 and Hercules X-1. Using data taken with the CASA-MIA detector over a five year period (1990-1995), we find no evidence for steady emission from either source at energies above 115 TeV. The derived upper limits on such emission are more than two orders of magnitude lower than earlier claimed detections. We also find no evidence for neutral particle or gamma-ray emission from either source on time scales of one day and 0.5 hr. For Cygnus X-3, there is no evidence for emission correlated with the 4.8 hr X-ray periodicity or with the occurrence of large radio flares. Unless one postulates that these sources were very active earlier and are now dormant, the limits presented here put into question the earlier results, and highlight the difficulties that possible future experiments will have in detecting gamma-ray signals at ultra-high energies.Comment: 26 LaTeX pages, 16 PostScript figures, uses psfig.sty to be published in Physical Review

Identifying patient-important outcomes in polycystic kidney disease: An international nominal group technique study

AIM: Patients with autosomal dominant polycystic kidney disease (ADPKD) are at increased risk of premature mortality, morbidities and complications, which severely impair quality of life. However, patient-centered outcomes are not consistently reported in trials in ADPKD, which can limit shared decision-making. We aimed to identify outcomes important to patients and caregivers and the reasons for their priorities. METHODS: Nominal group technique was adopted involving patients with ADPKD and caregivers who were purposively selected from eight centres across Australia, France and the Republic of Korea. Participants identified, ranked and discussed outcomes for trials in ADPKD. We calculated an importance score (0-1) for each outcome and conducted thematic analyses. RESULTS: Across 17 groups, 154 participants (121 patients, 33 caregivers) aged 19 to 78 (mean 54.5 years) identified 55 outcomes. The 10 highest ranked outcomes were: kidney function (importance score 0.36), end-stage kidney disease (0.32), survival (0.21), cyst size/growth (0.20), cyst pain/bleeding (0.18), blood pressure (0.17), ability to work (0.16), cerebral aneurysm/stroke (0.14), mobility/physical function (0.12), and fatigue (0.12). Three themes were identified: threatening semblance of normality, inability to control and making sense of diverse risks. CONCLUSION: For patients with ADPKD and their caregivers, kidney function, delayed progression to end-stage kidney disease and survival were the highest priorities, and were focused on achieving normality, and maintaining control over health and lifestyle. Implementing these patient-important outcomes may improve the meaning and relevance of trials to inform clinical care in ADPKD

Charge density wave ordering in NbSe3: possible models and the experimental evidence

Charge density wave (CDW) ordering in the prototypical low-dimensional compound NbSe3 is reconsidered. We show that the widely accepted CDW model with two incommensurate modulations, q1 = (0,0.241,0) and q2 = (0.5,0.260,0.5), localized on type-III and type-I bi-capped trigonal prismatic (BCTP) columns, does not explain some details, revealed by various microscopic methods. The suggested alternative explanation is in a better accord with the entire experimental evidence, including low-temperature (LT) scanning tunneling microscopy (STM) results. It is based on the existence of modulated layered nano-domains formed below both CDW onset temperatures. According to this model, two of the three slightly different BCTP types of columns are modulated by the same wave vector, either q1 or q2, which can easily switch over in a domain as a whole. This approach explains the presence of the q2 modulation in the STM images recorded above the T2 CDW transition and the absence of the q2 satellites in the corresponding diffraction patterns. The long periodic modulation, detected by LT STM is attributed to a beating between the two CDWs, centered on adjacent columns of the same type. These pairs of columns, both either of type-III or type-I, modulated by the two alternative CDWs, represent the basic modulation units, ordered into nano-domains