An experiment for the measurement of the bound-beta decay of the free neutron

The hyperfine-state population of hydrogen after the bound-beta decay of the neutron directly yields the neutrino left-handedness or a possible right-handed admixture and possible small scalar and tensor contributions to the weak force. Using the through-going beam tube of a high-flux reactor, a background free hydrogen rate of ca. 3 s$^{-1}$ can be obtained. The detection of the neutral hydrogen atoms and the analysis of the hyperfine states is accomplished by Lamb shift source type quenching and subsequent ionization. The constraints on the neutrino helicity and the scalar and tensor coupling constants of weak interaction can be improved by a factor of ten.Comment: 9 pages, 5 figures. Submitted to EPJ

Production of para-- and orthopositronium at relativistic heavy ion colliders

We consider the ortho-- and parapositronium production in the process $AA \to AA+$ Ps where A is a nucleus with the charge number Z. The inclusive cross section and the energy distribution of the relativistic Ps are calculated which are of primary interest from the experimental point of view. The accuracy of the corresponding cross sections is given by omitting terms $\sim (Z\alpha )^2/L^2$ for the para--Ps and $\sim (Z\alpha)^2/L$ for the ortho--Ps production where $L=\ln{\gamma^2} \approx 9$ and 16 for the RHIC and the LHC. Within this accuracy the multiphoton (Coulomb) corrections are taken into account. We show that the RHIC and the LHC will be Ps factories with a productions rate of about $10^5 \div 10^8$ relativistic Ps per day. The fraction of the ortho--Ps is expected to be of the same order as that of the para--Ps for Au--Au and Pb--Pb collisions.Comment: 22 pages, 5 figures, RevTeX, misprint correcte

Production of the Smallest QED Atom: True Muonium (mu^+ mu^-)

The "true muonium" (mu^+ mu-) and "true tauonium" (tau^+ tau^-) bound states are not only the heaviest, but also the most compact pure QED systems. The rapid weak decay of the tau makes the observation of true tauonium difficult. However, as we show, the production and study of true muonium is possible at modern electron-positron colliders.Comment: 4 pages, ReVTeX, 4 eps figures; minor wording changes and reordering of a reference. Version accepted by Phys. Rev. Let

The Influence of Strong Interaction on the Pionium Wave Functions at Small Distances

The influence of strong $\pi^+\pi^-$ interaction of the behaviour of pionium nS-state wave functions at small distance are investigated both analytically (perturbatively) and so numerically. It is shown that in the whole the accounting of strong interaction results in multiplying of pure Coulomb pionium wave functions by some function practically independent on value of principal quantum number n. Due to this reason the n-independence of probability of $\pi^+\pi^-$ atom production in nS-state remains the same as in case of pure Coulomb $\pi^+\pi^-$ interactionComment: 4 pages, 2 figure

Bound-state beta-decay of a neutron in a strong magnetic field

The beta-decay of a neutron into a bound $(pe^-)$ state and an antineutrino in the presence of a strong uniform magnetic field ($B \gtrsim 10^{13}$ G) is considered. The beta-decay process is treated within the framework of the standard model of weak interactions. A Bethe-Salpeter formalism is employed for description of the bound $(pe^-)$ system in a strong magnetic field. For the field strengths $10^{13}$ G$\lesssim B \lesssim10^{18}$ G the estimate for the ratio of the bound-state decay rate $w_b$ and the usual (continuum-state) decay rate $w_c$ is derived. It is found that in such strong magnetic fields $w_b/w_c \sim 0.1-0.4$. This is in contrast to the field-free case, where $w_b/w_c \simeq 4.2 \times 10^{-6}$ [J. N. Bahcall, Phys. Rev. {\bf 124}, 495 (1961); L. L. Nemenov, Sov. J. Nucl. Phys. {\bf 15}, 582 (1972); X. Song, J. Phys. G: Nucl. Phys. {\bf 13}, 1023 (1987)]. The dependence of the ratio $w_b/w_c$ on the magnetic field strength $B$ exhibits a logarithmic-like behavior. The obtained results can be important for applications in astrophysics and cosmology.Comment: 22 pages (revtex4), 1 figure; v2: more detailed discussion on astrophysical applications in conclusion section, accepted for publication in Phys. Rev.

Production of relativistic positronium in collisions of photons and electrons with nuclei and atoms

We consider the production of ultrarelativistic positronium (Ps) in $\gamma A \to Ps + A$ and $e A \to Ps + e A$ processes where $A$ is an atom or a nucleus with charge $Ze$. For the photoproduction of para- and ortho-Ps and the electroproduction of para-Ps we obtain the most complete description compared with previous works. It includes high order $Z \alpha$ corrections and polarization effects. The accuracy of the obtained cross sections is determined by omitted terms of the order of the inverse Ps Lorentz factor squared. The studied high order multi-photon electroproduction of ortho-Ps dominates for the collision of electrons with heavy atoms over the bremsstrahlung production from the electron via a virtual photon proposed by Holvik and Olsen. Our results complete and correct the studies of those authors.Comment: 19 pages, 9 figures, RevTex; v2: minor corrections for the accuracy of the results, a discussion of the literature added in a footnote, one additional reference; v3: diagram of Fig.2 correcte

Dynamics of the Pionium with the Density Matrix Formalism

The evolution of pionium, the $\pi^+ \pi^-$ hydrogen-like atom, while passing through matter is solved within the density matrix formalism in the first Born approximation. We compare the influence on the pionium break-up probability between the standard probabilistic calculations and the more precise picture of the density matrix formalism accounting for interference effects. We focus our general result in the particular conditions of the DIRAC experiment at CERN.Comment: 14 pages, 2 figures, submitted to J. Phys. B: At. Mol. Phy

Thermal nociceptive properties of trigeminal afferent neurons in rats

<p>Abstract</p> <p>Background</p> <p>Although nociceptive afferents innervating the body have been heavily studied form many years, much less attention has been paid to trigeminal afferent biology. In particular, very little is known concerning trigeminal nociceptor responses to heat, and almost nothing in the rat. This study uses a highly controlled and reproducible diode laser stimulator to investigate the activation of trigeminal afferents to noxious skin heating.</p> <p>Results</p> <p>The results of this experiment demonstrate that trigeminal thermonociceptors are distinct from themonociceptors innervating the limbs. Trigeminal nociceptors have considerably slower action potential conduction velocities and lower temperature thresholds than somatic afferent neurons. On the other hand, nociceptors innervating both tissue areas separate into those that respond to short pulse, high rate skin heating and those that respond to long pulse, low rate skin heating.</p> <p>Conclusions</p> <p>This paper provides the first description in the literature of the in vivo properties of thermonociceptors in rats. These finding of two separate populations aligns with the separation between C and A-delta thermonociceptors innervating the paw, but have significant differences in terms of temperature threshold and average conduction velocities. An understanding of the temperature response properties of afferent neurons innervating the paw skin have been critical in many mechanistic discoveries, some leading to new pain therapies. A clear understanding of trigeminal nociceptors may be similarly useful in the investigation of trigeminal pain mechanisms and potential therapies.</p

Effect of adherent perinephric fat on outcomes of nephron-sparing treatment of renal cell cancer

Introduction. Nephrometric scales have been developed to determine the appropriate surgical tactics and to predict intraoperative values more accurately, considering the characteristics of the renal tumour. However, there is a need to assess the perinephric fat. The Mayo Adhesive Probability (MAP) scale aims to identify adherent perinephric fat (APF) or 'complex' paranephric fat preoperatively.Objective. To evaluate the effect of APF on intraoperative and functional outcomes of patients with renal cell cancer (RCC) who underwent laparoscopic partial nephrectomy.Materials &amp; methods. We analysed 118 patients with localised RCC who underwent laparoscopic partial nephrectomy. At the preoperative stage, according to the results of contract-enhanced msCT, the presence of APF was assessed using the MAP scale. At the same time, the thickness of the posterior perinephric fat was measured and the grade of its twisting was assessed. As a result, the patients were divided into two groups: group 1 MAP 0 – 2 pts (no APF) 34 patients and group 2 MAP 3 – 5 pts (presence of APF) 84 patients. In each group, the following indicators were assessed: stage according to the TNM classification, mean age and BMI, average nephrometry score according to the R.E.N.A.L. system, glomerular filtration rate (GFR).Results. The median surgery time for group 1 patients was 115.0 [92.5; 142.5] min, for group 2 — 130.0 [101.3; 180.0] min. The median warm ischemia time in patients in group 1 was 15 [0; 20] min, in group 2 — 12 [0; 18] min. The median blood loss in the groups 1 and 2 was 50 [15; 100] and 50 [0; 100] ml, respectively. The mean GFR on the first day after surgery was 63.34 ± 18.40 ml/min/1.73 m2 in group 1 and 55.09 ± 16.01 ml/min/1.73 m2 in group 2. Openings of the pyelocalyceal system were observed in 8 (23.53%) and 23 (27.38%) patients in groups 1 and 2, respectively. A positive surgical margin was detected one patient in group 1 and two in group 2. Early postoperative complications in group 1 were four patients and group 2 — 15 patients.Conclusion. The presence of APF and its severity can be effectively assessed using the MAP score, which is promising, but is limited only to the prognostic of APF without correlation with nephrometric scales that assess tumour anatomy parameters. However, the issue of developing a unified assessment system that includes APF and kidney morphometry is currently open, and the definition of APF is still subjective and requires an objective analysis to obtain more accurate outcomes

The extraction of hadronic parameters from experiments on pionium

Experimental values of the lifetime of the 1s level of pionium and of the difference between the energies of the 2s and 2p levels yield values of the a(0c) and a(cc) elements of the s-wave scattering matrix for the 2-channel (pi+ pi-, pi0 pi0) system at the pi+ pi- threshold. We develop a method for obtaining the isospin invariant quanties a20 - a00 and 2a00 + a20 from a(0c) and a(cc). We emphasize that the isospin invariant scattering lengths a00 and a20 universally used in the literature cannot be considered to be purely hadronic quantities.Comment: 17 pages, Revtex, 1 postscript figure, new version of figure which removes ghostscript problem