Casimir-Polder intermolecular forces in minimal length theories

Generalized uncertainty relations are known to provide a minimal length $\hbar\sqrt{\beta}$. The effect of such minimal length in the Casimir-Polder interactions between neutral atoms (molecules) is studied. The first order correction term in the minimal uncertainty parameter is derived and found to describe an attractive potential scaling as $r^{-9}$ as opposed to the well known $r^{-7}$ long range retarded potential.Comment: 1 Figure. Version published by Physical Review D. Few references added, typos correcte

Cell proliferation and oncogene expression after bile duct ligation in the rat: Evidence of a specific growth effect on bile duct cells

The proliferative response of the rat liver was measured after temporary or permanent total biliary obstruction (BDO) and in different regions after selective ligation of the lobar ducts draining the right 60% of the hepatic mass. The results were compared with those after 70% partial hepatectomy (PH). Cell proliferation was assessed globally by measuring DNA synthesis and stratified to the separate cell populations with cytostaining techniques that allowed distinction of hepatocytes, duct cells, and nonparenchymal cells (NPCs). In selected experimental groups, gene expression was determined of transforming growth factor-β1 (TGFβ-1), prothrombin, c-erb-B2, transforming growth factor alpha (TGFα), human Cyclophilin (CyP), and 28S ribosomal RNA. The stimulation of a proliferative response to total BDO required obstruction for longer than 24 hours, but after this deligation did not switch off regeneration. In the first week after permanent BDO, there was progressive infiltration of NPCs, fibrous linkage of some portal areas, and a crescendo of DNA synthesis that was obvious at 24 hours, maximal at 48 hours, and back nearly to baseline at 6 days. At the 2-day mark, the bile duct cells had a 17-fold increase in proliferation, accompanied by a threefold to fourfold increase in hepatocyte renewal. Little or no increase in expression of TGFα or the hepatocyte-specific prothrombin gene was detectable in the first 48 hours, whereas levels of the oncogene c-erb-B2 that is associated with cholangiocarcinoma were expressed from 48 to 96 hours. Livers subjected to regional BDO with or without immunosuppressive treatment with FK 506 and cyclosporine had an inflammatory reaction only on the side with ligated ducts. DNA synthesis increased in both the obstructed and freely draining lobes to approximately half the level that occurred after total BDO. The proliferation of the obstructed side was similar to the mixed duct cell/hepatocyte response after total BDO, but this almost exclusively involved duct cells on the freely draining side. In contrast to the findings after BDO, livers after PH regenerated maximally at 24 hours rather than 48 hours, had a predominantly noninflammatory hepatocyte as opposed to duct cell response, and had marked expression of the prothrombin and TGFα genes but only weakly and late of c-erb-B2 messenger RNA. The results show that the liver responds as a whole and in a biologically intelligent way to the nature of the injury inflicted on any part of it. It further implies the presence of humoral communications and control networks that assure organ homeostasis and relate this to total body homeostasis. © 1995

HORIZONTAL TWO-PHASE FLOW PATTERN RECOGNITION

In the present work a Wire Mesh Sensor (WMS) has been adopted to characterize the air-water two-phase flow in a test section consisting of a horizontal Plexiglas pipe of internal diameter 19.5 mm and total length of about 6 m. The flow quality ranges from 0 to 0.73 and the superficial velocity ranges from 0.145 to 31.94 m/s for air and from 0.019 to 2.62 m/s for water. The observed flow patterns are stratified-bubble-slug/plug-annular. The WMS consists of two planes of parallel wire grids (16x16) that are placed across the channel at 1.5 mm and span over the measuring cross section. The wires of both planes cross under an angle of 90°, with a diameter Dwire of 70 μm and a pitch equal to 1.3 mm. The void fraction profiles are derived from the sensor data and their evolution in time and space is analyzed and discussed. The dependence of the signals on the measured fluid dynamic quantities is discussed too. The main task is to predict which flow pattern will exist under any set of operating conditions as well as to predict the value of characteristic flow parameters

Experimental Study on the Flow Patterns and Two-phase Pressure Drops in a Horizontal Impacting T- Junction

The present paper analyzes the experimental results concerning the flow patterns and pressure drops in two-phase flow through an horizontal impacting T-junction, whose outlet pipes are aligned and perpendicular to the inlet pipe. The test section consists of plexiglass pipes with inner diameter of 10 mm. A mixture of water and air at ambient temperature and pressures up to 2.4 bar flows through the T-junction, with different splitting of flow rates in the two outlet branches; superficial velocities of air and water in the inlet pipe are varied up to a maximum of 35 m/s and 3.5 m/s respectively. The flow patterns occurring in the inlet and branch pipes were compared with the predictions of Baker’s and Taitel – Dukler’s maps. The pressure drops along the branches have been measured relatively to different splitting of the flow rate through the two branches and the pressure loss coefficients in the junction have been evaluated. Friction pressure drops have allowed us to evaluate two-phase friction multipliers, which have then been compared to the predictions of Lockhart-Martinelli, and Friedel correlations. Local pressure drops were extrapolated at the junction centre and analyzed; the two-phase multiplier has been evaluated and compared with the predictions of Chisholm correlation; the value of the empirical coefficient that minimizes the discrepancies has also been evaluated

Single Top Production at the Next Generation Linear e+e- Colliders

Present limits on the top mass from LEP1 and Tevatron point to a top quark that is considerably heavier than the $W$ vector boson in the standard model. Hence, e+e- colliders with \sqrt{s} \simeq 300 GeV (the c.m. energy foreseen at the first phase of the Next Linear e+e- Collider) could be well below the energy threshold for real top-pair production. We argue that, if this is the case, single top production through the process e+e- --> t\bar{b}W- (\bar{t}bW+), where t\bar{b} (\bar{t}b) are produced mainly by means of a virtual W, becomes the dominant top production mechanism. Total cross sections and kinematical distributions are evaluated and numerical results are given in ranges of m_t and \sqrts{s} where single top production can be of relevance. The relative importance of virtual-W and virtual-t contributions to the process is discussed.Comment: 20 pages, LaTeX + feynman.tex, 10 compressed (tar.Z) postscript figures included in a separate uuencoded file, revised version of Rome1 Preprint n.979 (1993), Dec 29, 1993. (In this revised version -- accepted for publication on Zeit. fur Phys.C in Jan 24, 1994 -- some sentences and 3 new refs. have been added with respect to the first one

Two-Phase flow instrumentation for nuclear accidents simulation, Keynote lecture KN3, pp. 1-23, Procs. 32nd UIT Heat Transfer Conference, Pisa, June 23-25, 2014.

The paper presents the research work performed at the Energy Department of the Politecnico di Torino, concerning the development of two-phase flow instrumentation and of models, based on the analysis of experimental data, that are able to interpret the measurement signals. The study has been performed with particular reference to the design of power plants, such as nuclear water reactors, where the two-phase flow thermal fluid dynamics must be accurately modeled and predicted. In two-phase flow typically a set of different measurement instruments (Spool Piece - SP) must be installed in order to evaluate the mass flow rate of the phases in a large range of flow conditions (flow patterns, pressures and temperatures); moreover, an interpretative model of the SP need to be developed and experimentally verified. The investigated meters are: Turbine, Venturi, Impedance Probes, Concave sensors, Wire mesh sensor, Electrical Capacitance Probe. Different instrument combinations have been tested, and the performance of each one has been analyzed

Ultra Low Momentum Neutron Catalyzed Nuclear Reactions on Metallic Hydride Surfaces

Ultra low momentum neutron catalyzed nuclear reactions in metallic hydride system surfaces are discussed. Weak interaction catalysis initially occurs when neutrons (along with neutrinos) are produced from the protons which capture ``heavy'' electrons. Surface electron masses are shifted upwards by localized condensed matter electromagnetic fields. Condensed matter quantum electrodynamic processes may also shift the densities of final states allowing an appreciable production of extremely low momentum neutrons which are thereby efficiently absorbed by nearby nuclei. No Coulomb barriers exist for the weak interaction neutron production or other resulting catalytic processes.Comment: 4 pages, ReVTeX forma

Stereotaxic gamma knife surgery in treatment of critically located pilocytic astrocytoma: preliminary result

BACKGROUND: Low-grade gliomas are uncommon primary brain tumors, located more often in the posterior fossa, optic pathway, and brain stem and less commonly in the cerebral hemispheres. CASE PRESENTATIONS: Two patients with diagnosed recurrent cystic pilocytic astrocytoma critically located within the brain (thalamic and brain stem) were treated with gamma knife surgery. Gamma knife surgery (GKS) did improve the patient's clinical condition very much which remained stable later on. Progressive reduction on the magnetic resonance imaging (MRI) studies of the solid part of the tumor and almost disappearance of the cystic component was achieved within the follow-up period of 36 months in the first case with the (thalamic located lesion) and 22 months in the second case with the (brain stem located lesion). CONCLUSION: Gamma knife surgery represents an alternate tool in the treatment of recurrent and/or small postoperative residual pilocytic astrocytoma especially if they are critically locate

Thermal hydraulic analysis of Alfred bayonet tube steam generator

The paper analyzes the performance of ALFRED steam generator from the thermal-hydraulic point of view highlighting the effect of some design features. The parameters object of the study are the regenerative heat transfer, the dimension of the inner tube and the length of the bayonet. The system code RELAP5-3D/2.4.2 has been chosen for the analysis. Sensitivities analysis allowed the determination of the different design parameters influence, here briefly summarized. The increase of regenerative heat transfer affects the efficiency of the steam generator through a degradation of the outlet steam quality: the number of bayonet tubes required to remove the nominal power increases with the increase of the global heat transfer coefficient of the inner tube. A higher inner diameter results in a larger surface area for the regenerative heat transfer and in a higher heat transfer coefficient in the annular region because of the reduction of the cross section. The result is an improvement of the performances of the steam generator thanks to the dimension reduction of the annular gap. Finally, if the height of the bayonet tube is reduced by 1 meter, the number of bayonet tubes required to remove the nominal power increases up to 20%