Comment on The Evidence for a Pentaquark and Kinematic Reflections

The Regge exchange model used by Dzierba et al. is shown to be questionable, since the pion pole term is not allowed. Hence the Regge amplitudes in their calculation are exaggerated. The amount of kinematic reflection in the mass spectrum of the (nK+) system, which is one decay channel of a possible pentaquark, is not well justified in the fitting procedure used by Dzierba et al., as shown by comparison with the (K+K-) invariant mass spectrum, which is one decay channel of the a_2 and f_2 tensor mesons. While kinematic reflections are still a concern in some papers that have presented evidence for the pentaquark, better quantitative calculations are needed to demonstrate the significance of this effect.Comment: Comment submitted to Phys. Rev. D (no figures

Energy Calibration of the JLab Bremsstrahlung Tagging System

In this report, we present the energy calibration of the Hall B bremsstrahlung tagging system at the Thomas Jefferson National Accelerator Facility. The calibration was performed using a magnetic pair spectrometer. The tagged photon energy spectrum was measured in coincidence with $e^+e^-$ pairs as a function of the pair spectrometer magnetic field. Taking advantage of the internal linearity of the pair spectrometer, the energy of the tagging system was calibrated at the level of $\pm 0.1$. The absolute energy scale was determined using the $e^+e^-$ rate measurements close to the end-point of the photon spectrum. The energy variations across the full tagging range were found to be $<3$ MeV.Comment: 15 pages, 12 figure

Splenic morphometric characteristics in infectious mononucleosis (ultrasonic study)

The spleen is a secondary immune and the largest organ of the reticuloendothelial system, actively involved during infectious mononucleosis. Clinically, assessing a degree of organ involvement in the pathological process seems unlikely. As a rule, only palpation and percussion are used to determine the size of the spleen, which represents a late and subjective sign of potential splenomegaly. Ultrasound examination provides ample opportunities to estimate the spleen size during infectious mononucleosis. Our study was aimed at identifying morphometric and Doppler ultrasound changes in the spleen in patients with infectious mononucleosis. Materials and methods. There were enrolled 24 patients with infectious mononucleosis to be compared with 30 healthy medical institute students in control group. All participants underwent splenic ultrasound examination. Spleen echotexture and contour clarity together with measuring linear dimensions: length, width, and thickness were analyzed. Splenic artery and vein velocity parameters were measured at the gates of the spleen. Elastographic window for fibroelastometry was positioned within the window for standard grayscale examination. Measurements were performed at 5 or more points of the spleen parenchyma at least 4—5 mm away from the capsular zone and the zone of large vessels. Based on the morphometric measurements obtained, the mass, spleen mass coefficient (SMC), as well as the spleen mass/body height ratio and spleen mass/body surface area ratio were calculated. Results. We found that patients with infectious mononucleosis had the length, thickness and weight of the spleen significantly greater than those observed in control group. However, the mass of the spleen varies widely and justified to calculate the CMS as an objective criterion to assess the size of the spleen. It was revealed that infectious mononucleosis may proceed in one of the three variants of the splenic response: decreased size, CMR &lt; 1.5; normal size, CMR ranged from 1.5 to 4; splenomegaly, CMR &gt; 4. Splenomegaly is associated with increased organ stiffness, peak blood flow velocity and pressure in v. lienalis, as well as periportal lymphadenopathy. Identified changes are characteristics of young patients. Conclusion. Ultrasound examination of the spleen is of high diagnostic value for patients with infectious mononucleosis allowing highly accurate assessment state of the immune organs in the acute disease period. At the preclinical stage, gradation of splenomegaly is possible depending on its intensity, assessed hemodynamics and organ stiffness

Search for Higher Flavor Multiplets in Partial Wave Analyses

The possible existence of higher multi-quark flavor multiplets of baryons is investigated. We argue that the S-matrix should have poles with any quantum numbers, including those which are exotic. This argument provides a novel justification for the existence of hadrons with arbitrary exotic structure. Though it does not constitute a proof, there are still no theoretical arguments against exotics. We then consider KN and piN scattering. Conventional and modified partial-wave analyses provide several sets of candidates for correlated pairs (Theta1, Delta), each of which could label a related 27-plet. Properties of the pairs (masses, mass orderings, spin-parity quantum numbers) do not quite correspond to the current theoretical expectations. Decay widths of the candidates are either wider or narrower than expected. Possible reasons for such disagreements are briefly discussed.Comment: 12 pages, 1 figure; v2: references corrected; v3: minor changes, to appear in Eur.Phys.J.

ВНУТРИ- И МЕЖИССЛЕДОВАТЕЛЬСКАЯ ВОСПРОИЗВОДИМОСТЬ ПОКАЗАТЕЛЕЙ ЛИНЕЙНЫХ РАЗМЕРОВ ПЕЧЕНИ ПРИ УЛЬТРАЗВУКОВОМ ИССЛЕДОВАНИИ

Introduction. Hepatomegaly is the most frequent and easily detectable, sometimes the only chronic liver disease symptom. An objective assessment of liver size with ultrasound is complex.Aim. To assess the intra- and inter-research reproducibility of ultrasound liver linear measurements.Materials and methods. To study the reproducibility of liver measurements, each patient was examined by two specialists of ultrasound diagnostics performing 24 liver measurements twice.Results. The average errors for all left lobe measurements for more experienced doctor vary from 4 to 13,5% and  for less experienced — from 5 to 22%. When examining the right lobe, the average errors for both sonographers  don’t exceed 10%.Conclusion. The anteroposterior size of the left lobe and maximum craniocaudal size of the right lobe are the most reproducible. We recommend obtain liver measurements of the right lobe at the anterior axillary line due to the lower bulge of the chest, which allows the transducer to be installed parallel to the sagittal plane.Введение. Гепатомегалия представляет собой наиболее частое и легко определяемое, порой единственное проявление хронических заболеваний печени. Однако объективная оценка размеров печени при ультразвуковом исследовании является сложной задачей.Цель: дать оценку внутри- и межисследовательской воспроизводимости линейных измерений печени при ультразвуковом исследовании.Материалы и методы. Для изучения воспроизводимости измерений печени каждый пациент был обследован двумя врачами ультразвуковой диагностики. Каждым врачом проводилось 24 измерения печени по два раза.Результаты. Показатели средних погрешностей по всем измерениям левой доли для врача, имеющего больший опыт работы, колеблются от 4 до 13,5%, а для врача с меньшим опытом работы — от 5 до 22%. При исследовании правой доли показатели средних погрешностей для обоих врачей не превышают 10%. Заключение. При измерении линейных размеров левой доли печени наиболее воспроизводимым является переднезадний размер, а при измерении линейных размеров правой доли — максимальный краниокаудальный размер. Мы рекомендуем проводить измерения правой доли печени по передней подмышечной линии из-за меньшей выпуклости грудной клетки, что позволяет установить датчик параллельно сагиттальной плоскости.

Polynomiality of unpolarized off-forward distribution functions and the D-term in the chiral quark-soliton model

Mellin moments of off-forward distribution functions are even polynomials of the skewedness parameter. This constraint, called polynomiality property, follows from Lorentz- and time-reversal invariance. We prove that the unpolarized off-forward distribution functions in the chiral quark-soliton model satisfy the polynomiality property. The proof is an important contribution to the demonstration that the description of off-forward distribution functions in the model is consistent. As a byproduct of the proof we derive explicit model expressions for moments of the D-term and compute the first coefficient in the Gegenbauer expansion for this term.Comment: 18 pages, no figures. Corrections and improvements in section 6. To appear in Phys.Rev.

Molecular Remodeling of Tip Links Underlies Mechanosensory Regeneration in Auditory Hair Cells

Sound detection by inner ear hair cells requires tip links that interconnect mechanosensory stereocilia and convey force to yet unidentified transduction channels. Current models postulate a static composition of the tip link, with protocadherin 15 (PCDH15) at the lower and cadherin 23 (CDH23) at the upper end of the link. In terminally differentiated mammalian auditory hair cells, tip links are subjected to sound-induced forces throughout an organism\u27s life. Although hair cells can regenerate disrupted tip links and restore hearing, the molecular details of this process are unknown. We developed a novel implementation of backscatter electron scanning microscopy to visualize simultaneously immuno-gold particles and stereocilia links, both of only a few nanometers in diameter. We show that functional, mechanotransduction-mediating tip links have at least two molecular compositions, containing either PCDH15/CDH23 or PCDH15/PCDH15. During regeneration, shorter tip links containing nearly equal amounts of PCDH15 at both ends appear first. Whole-cell patch-clamp recordings demonstrate that these transient PCDH15/PCDH15 links mediate mechanotransduction currents of normal amplitude but abnormal Ca(2+)-dependent decay (adaptation). The mature PCDH15/CDH23 tip link composition is re-established later, concomitant with complete recovery of adaptation. Thus, our findings provide a molecular mechanism for regeneration and maintenance of mechanosensory function in postmitotic auditory hair cells and could help identify elusive components of the mechanotransduction machinery

Hadrons in the Nuclear Medium

Quantum Chromodynamics, the microscopic theory of strong interactions, has not yet been applied to the calculation of nuclear wave functions. However, it certainly provokes a number of specific questions and suggests the existence of novel phenomena in nuclear physics which are not part of the the traditional framework of the meson-nucleon description of nuclei. Many of these phenomena are related to high nuclear densities and the role of color in nucleonic interactions. Quantum fluctuations in the spatial separation between nucleons may lead to local high density configurations of cold nuclear matter in nuclei, up to four times larger than typical nuclear densities. We argue here that experiments utilizing the higher energies available upon completion of the Jefferson Laboratory energy upgrade will be able to probe the quark-gluon structure of such high density configurations and therefore elucidate the fundamental nature of nuclear matter. We review three key experimental programs: quasi-elastic electro-disintegration of light nuclei, deep inelastic scattering from nuclei at $x>1$, and the measurement of tagged structure functions. These interrelated programs are all aimed at the exploration of the quark structure of high density nuclear configurations. The study of the QCD dynamics of elementary hard processes is another important research direction and nuclei provide a unique avenue to explore these dynamics. We argue that the use of nuclear targets and large values of momentum transfer at would allow us to determine whether the physics of the nucleon form factors is dominated by spatially small configurations of three quarks.Comment: 52 pages IOP style LaTex file and 20 eps figure

Correlated Strength in Nuclear Spectral Function

We have carried out an (e,e'p) experiment at high momentum transfer and in parallel kinematics to measure the strength of the nuclear spectral function S(k,E) at high nucleon momenta k and large removal energies E. This strength is related to the presence of short-range and tensor correlations, and was known hitherto only indirectly and with considerable uncertainty from the lack of strength in the independent-particle region. This experiment confirms by direct measurement the correlated strength predicted by theory.Comment: 4 pages, 2 figures, accepted by Phys. Rev. Let

The proton and deuteron F_2 structure function at low Q^2

Measurements of the proton and deuteron $F_2$ structure functions are presented. The data, taken at Jefferson Lab Hall C, span the four-momentum transfer range $0.06 < Q^2 < 2.8$ GeV$^2$, and Bjorken $x$ values from 0.009 to 0.45, thus extending the knowledge of $F_2$ to low values of $Q^2$ at low $x$. Next-to-next-to-leading order calculations using recent parton distribution functions start to deviate from the data for $Q^2<2$ GeV$^2$ at the low and high $x$-values. Down to the lowest value of $Q^2$, the structure function is in good agreement with a parameterization of $F_2$ based on data that have been taken at much higher values of $Q^2$ or much lower values of $x$, and which is constrained by data at the photon point. The ratio of the deuteron and proton structure functions at low $x$ remains well described by a logarithmic dependence on $Q^2$ at low $Q^2$.Comment: 3 figures, submitted pape