Polarized proton acceleration in ultraintense laser interaction with near-critical-density plasmas

The production of polarized proton beams with multi-GeV energies in ultraintense laser interaction with targets is studied with three-dimensional particle-in-cell simulations. A near-critical density plasma target with prepolarized proton and tritium ions is considered for the proton acceleration. The prepolarized protons are initially accelerated by laser radiation pressure before injection and further acceleration in a bubblelike wakefield. The temporal dynamics of proton polarization is tracked via the Thomas-Bargmann-Michel-Telegdi equation and it is found that the proton polarization state can be altered by both the laser field and the magnetic component of the wakefield. The dependence of the proton acceleration and polarization on the ratio of the ion species is determined and it is found that the protons can be efficiently accelerated as long as their relative fraction is less than 20%, in which case the bubble size is large enough for the protons to obtain sufficient energy to overcome the bubble injection threshold.

Production of HD Molecules in Definite Hyperfine Substates

Polarized atomic beam sources have been in operation for many years to produce either nuclear polarized atomic hydrogen or deuterium beams. In recent experiments, such a source was used to polarize both isotopes independently at the same time. By recombination of the atoms, hydrogen-deuterium molecules with all possible nuclear spin combinations can be created. Those spin isomers are useful for further applications, like precision spectroscopy, as polarized targets for laser-particle acceleration, polarized fuel for fusion reactors, or as an option for future measurements of electric dipole moments.

Nm-sized cryogenic hydrogen clusters for a laser-driven proton source

A cryogenic hydrogen cluster-jet target is described which has been used for laser-plasma interaction studies. Major advantages of the cluster-jet are, on the one hand, the compatibility to pulsed high repetition lasers as the target is operated continuously and, on the other hand, the absence of target debris. The cluster-jet target was characterized using the Mie-scattering technique allowing to determine the cluster size and to compare the measurements with an empirical formula. In addition, an estimation of the cluster beam density was performed. The system was implemented at the high power laser system ARCTURUS, and the measurements show the acceleration of protons after irradiation of the cluster target by high intensity laser pulses with a repetition rate of 5 Hz.

Isotensor Dibaryon in the pp→ppπ^{+}π^{-} Reaction?

Exclusive measurements of the quasifree pp→ppπ^{+}π^{-} reaction have been carried out at WASA@COSY by means of pd collisions at T_{p}=1.2  GeV. Total and differential cross sections have been extracted covering the energy region T_{p}=1.08-1.36  GeV, which is the region of N^{*}(1440) and Δ(1232)Δ(1232) resonance excitations. Calculations describing these excitations by t-channel meson exchange are at variance with the measured differential cross sections and underpredict substantially the experimental total cross section. An isotensor ΔN dibaryon resonance with I(J^{P})=2(1^{+}) produced associatedly with a pion is able to overcome these deficiencies.

Spin Dependence of η Meson Production in Proton-Proton Collisions Close to Threshold

Taking advantage of the high acceptance and axial symmetry of the WASA-at-COSY detector, and the high polarization degree of the proton beam of COSY, the reaction p[over →]p→ppη has been measured close to threshold to explore the analyzing power A_{y}. The angular distribution of A_{y} is determined with the precision improved by more than 1 order of magnitude with respect to previous results, allowing a first accurate comparison with theoretical predictions. The determined analyzing power is consistent with zero for an excess energy of Q=15  MeV, signaling s-wave production with no evidence for higher partial waves. At Q=72  MeV the data reveal strong interference of Ps and Pp partial waves and cancellation of (Pp)^{2} and Ss^{*}Sd contributions. These results rule out the presently available theoretical predictions for the production mechanism of the η meson.

The Insect Ortholog of the Human Orphan Cytokine Receptor CRLF3 Is a Neuroprotective Erythropoietin Receptor

The cytokine erythropoietin (Epo) mediates various cell homeostatic responses to environmental challenges and pathological insults. While stimulation of vertebrate erythrocyte production is mediated by homodimeric “classical” Epo receptors, alternative receptors are involved in neuroprotection. However, their identity remains enigmatic due to complex cytokine ligand and receptor interactions and conflicting experimental results. Besides the classical Epo receptor, the family of type I cytokine receptors also includes the poorly characterized orphan cytokine receptor-like factor 3 (CRLF3) present in vertebrates including human and various insect species. By making use of the more simple genetic makeup of insect model systems, we studied whether CRLF3 is a neuroprotective Epo receptor in animals. We identified a single ortholog of CRLF3 in the beetle Tribolium castaneum, and established protocols for primary neuronal cell cultures from Tribolium brains and efficient in vitro RNA interference. Recombinant human Epo as well as the non-erythropoietic Epo splice variant EV-3 increased the survival of serum-deprived brain neurons, confirming the previously described neuroprotective effect of Epo in insects. Moreover, Epo completely prevented hypoxia-induced apoptotic cell death of primary neuronal cultures. Knockdown of CRLF3 expression by RNA interference with two different double stranded RNA (dsRNA) fragments abolished the neuroprotective effect of Epo, indicating that CRLF3 is a crucial component of the insect Epo-responsive receptor. This suggests that a common urbilaterian ancestor of the orphan human and insect cytokine receptor CRLF3 served as a neuroprotective receptor for an Epo-like cytokine. Our work also suggests that vertebrate CRLF3, like its insect ortholog, might represent a tissue protection-mediating receptor.

The insect central complex as model for heterochronic brain development-background, concepts, and tools

The adult insect brain is composed of neuropils present in most taxa. However, the relative size, shape, and developmental timing differ between species. This diversity of adult insect brain morphology has been extensively described while the genetic mechanisms of brain development are studied predominantly in Drosophila melanogaster. However, it has remained enigmatic what cellular and genetic mechanisms underlie the evolution of neuropil diversity or heterochronic development. In this perspective paper, we propose a novel approach to study these questions. We suggest using genome editing to mark homologous neural cells in the fly D. melanogaster, the beetle Tribolium castaneum, and the Mediterranean field cricket Gryllus bimaculatus to investigate developmental differences leading to brain diversification. One interesting aspect is the heterochrony observed in central complex development. Ancestrally, the central complex is formed during embryogenesis (as in Gryllus) but in Drosophila, it arises during late larval and metamorphic stages. In Tribolium, it forms partially during embryogenesis. Finally, we present tools for brain research in Tribolium including 3D reconstruction and immunohistochemistry data of first instar brains and the generation of transgenic brain imaging lines. Further, we characterize reporter lines labeling the mushroom bodies and reflecting the expression of the neuroblast marker gene Tc-asense, respectively.

Abashian-Booth-Crowe effect in basic double-pionic fusion: a new resonance?

We report on an exclusive and kinematically complete high-statistics measurement of the basic double-pionic fusion reaction pn→dπ(0)π(0) over the full energy region of the ABC effect, a pronounced low-mass enhancement in the ππ-invariant mass spectrum. The measurements, which cover also the transition region to the conventional t-channel ΔΔ process, were performed with the upgraded WASA detector setup at COSY. The data reveal the Abashian-Booth-Crowe effect to be uniquely correlated with a Lorentzian energy dependence in the integral cross section. The observables are consistent with a narrow resonance with m=2.37  GeV, Γ≈70  MeV and I(J(P))=0(3(+)) in both pn and ΔΔ systems. Necessary further tests of the resonance interpretation are discussed.

Dynamics of cryogenic jets: non-rayleigh breakup and onset of nonaxisymmetric motions

We report development of generators for periodic, satellite-free fluxes of monodisperse drops with diameters down to 10 microm from cryogenic liquids such as H2, N2, Ar, and Xe (and, as a reference fluid, water). While the break up of water jets can be described well by Rayleigh's linear theory, we find jet regimes for H2 and N2 which reveal deviations from this behavior. Thus, Rayleigh's theory is inappropriate for thin jets that exchange energy and/or mass with the surrounding medium. Moreover, at high evaporation rates, the axial symmetry of the dynamics is lost. When the drops pass into vacuum, frozen pellets form due to surface evaporation. The narrow width of the pellet flux paves the way towards various industrial and scientific applications.

Precision study of the eta3He system using the dp--> 3Heeta reaction

The differential and total cross sections for the dp--> 3Heeta reaction have been measured in a high precision high statistics COSY-ANKE experiment near threshold using a continuous beam energy ramp up to an excess energy Q of 11.3 MeV with essentially 100% acceptance. The kinematics allowed the mean value of Q to be determined to about 9 keV. Evidence is found for the effects of higher partial waves for Q >or= 4 MeV. The very rapid rise of the total cross section to its maximum value within 0.5 MeV of threshold implies a very large eta3He scattering length and hence the presence of a quasibound state extremely close to threshold.

Precision measurement of the quasifree pn-->dvarphi reaction close to threshold

The quasifree pn-->dvarphi reaction has been studied at the Cooler Synchrotron COSY-Jülich, using the internal proton beam incident on a deuterium cluster-jet target and detecting a fast deuteron in coincidence with the K+K- decay of the varphi meson. The energy dependence of the total and differential cross sections are extracted for excess energies up to 80 MeV by determining the Fermi momentum of the target neutron on an event-by-event basis. Though these cross sections are consistent with s-wave production, the kaon angular distributions show the presence of p waves at quite a low energy. Production on the neutron is found to be stronger than on the proton but not by as much as for the eta meson.

Near-threshold production of phi mesons in pp collisions

The pp-->ppphi reaction has been studied at the Cooler Synchrotron COSY-Jülich, using the internal beam and ANKE facility. Total cross sections have been determined at three excess energies epsilon near the production threshold. The differential cross section closest to threshold at epsilon=18.5 MeV exhibits a clear S wave dominance as well as a noticeable effect due to the proton-proton final-state interaction. Taken together with data for ppomega production, a significant enhancement of the phi/omega ratio of a factor 8 is found compared to predictions based on the Okubo-Zweig-Iizuka rule.

Evidence for an excited hyperon state in pp --> pK+Y0*

Indications for the production of a neutral excited hyperon in the reaction pp --> pK+Y0* are observed in an experiment performed with the ANKE spectrometer at COSY-Jülich at p(beam) = 3.65 GeV/c. Two final states were investigated simultaneously, viz. Y0* --> pi+X- and pi-X+, and consistent results were obtained in spite of the quite different experimental conditions. The parameters of the hyperon state are M(Y0*) = (1480 +/-15) MeV/c2 and gamma(Y0*) = (60 +/- 15) MeV/c2. The production cross section for Y0* decaying through these channels is of the order of few hundred nanobarns. Since the isospin of the Y0* has not been determined here, it could either be an observation of the sigma(1480), a one-star resonance of the Particle Data Group tables, or, alternatively, a lambda hyperon. Relativistic quark models for the baryon spectrum do not predict any excited hyperon in this mass range and so the Y0* may be of exotic nature.

a+0 (980)-resonance production in pp-->dK+K-0 reactions close to threshold

The reaction pp-->dK+K(-)0 has been investigated at an excess energy of Q=46 MeV above the K+K(-)0 threshold with ANKE at the cooler synchrotron COSY-Jülich. From the detected coincident dK(+) pairs, about 1000 events with a missing K(-)0 were identified, corresponding to a total cross section of sigma(pp-->dK+K(-)0)=[38+/-2(stat)+/-14(syst)] nb. Invariant-mass and angular distributions have been jointly analyzed and reveal s-wave dominance between the two kaons, accompanied by a p wave between the deuteron and the kaon system. This is interpreted in terms of a(+)0 (980)-resonance production.

An analysis of errors in blood component transfusion records with regard to quality improvement of data acquisition and to the performance of lookback and traceback procedures

BACKGROUND

Quality assurance of blood transfusion covers institutions, personnel, and procedures involved in preparing, issuing, and using blood components. The accuracy of data related to blood component transfusions is a tool for quality control in the transfusion service.

STUDY DESIGN AND METHODS

A study of the accuracy of data records of the transfusion service at the University Hospital of Erlangen, Germany, between June 1994 and May 1996 was carried out. All returned blood component transfusion report forms were examined for discrepancies between primary data records and clinical transfusion reports.

RESULTS

Blood components (n = 49,224) from allogeneic and autologous donations, packed red cells, fresh-frozen plasma, and platelet components that had been issued for transfusion were included in this evaluation. For 27.3 percent of all components issued, no transfusion report was returned to the blood bank. For the remaining 35,786 units, errors were found in 3.8 percent of the records. For 1.24 percent of all components, discrepant information related to the recipient's identity or the component's status was found; this affected the feasibility of lookback or traceback searches.

CONCLUSION

A remarkably high frequency of discrepancies exists between computerized blood bank records and the information recorded on returned blood transfusion forms. The processes of data acquisition and entry must be included in quality assurance efforts in transfusion medicine.

A survey of blood component use in a German university hospital

BACKGROUND

There are no recent studies on transfusion practice and blood use with regard to diagnoses of European recipients. We conducted a survey of blood component use, including packed red cells, fresh-frozen plasma, and platelets, in an acute-care university hospital in the Greater Nürnberg area.

STUDY DESIGN AND METHODS

A survey was carried out of blood component transfusion at a university hospital (Erlangen, Germany) between June 1994 and May 1996. Transfused units were listed by broad diagnostic categories formed from principal diagnoses of the recipients according to the International Classification of Diseases, Ninth Revision.

RESULTS

Among 100,497 discharged patients, 6,590 patients who received transfusion (6.6%) are represented in this survey. Of 28,440 red cell units and 8,592 fresh-frozen plasma units, 72.4 percent and 66.9 percent, respectively, were used in patients with neoplastic diseases, circulatory system diseases, or disorders of the digestive system. Of 2704 platelet units, 78.1 percent were transfused to patients with neoplastic or gastrointestinal diseases or diseases of blood-forming organs. These four diagnostic categories accounted for 77.7 percent of all costs of transfusion therapy. Males received 60.1 percent of all blood components transfused, and patients less than 65 years old received 68.0 percent.

CONCLUSION

This survey provides information on blood component usage in a German university hospital. It demonstrates the concentration of today's blood utilization among a few diagnostic categories. The study shows that detailed information on local blood use may be obtained quickly by using data available from transfusion services and medical record departments. This information is relevant for quality management of transfusion practice, cost analyses and for planning local and regional blood donation programs.

Coordinate control of the alpha- and beta-subunit genes of human chorionic gonadotropin by trophoblast-specific element-binding protein

The alpha- and beta-subunit genes of hCG are coordinately regulated in the trophectoderm of the early embryo and placenta. Placenta-specific expression of the alpha-subunit gene is determined by a composite enhancer made of three clustered components: cAMP-responsive elements, a GATA site, and the trophoblast-specific element (TSE). We have investigated the basis of placenta-specific expression of the major hCG beta-subunit gene, hCG beta 5. Enhancement of expression localizes to the region from -305 to -279, whereas full cAMP regulation requires the region from -305 to -249. Four DNAse-I footprints are present, three of which can be competed by the TSE element from the alpha-subunit gene. Methylation interference establishes that binding to the element located in the key region for expression, from -301 to -275, requires contacts with a CCNNNGGG core sequence that matches the alpha-subunit gene TSE. Sequence-specific DNA affinity chromatography using the alpha-subunit gene TSE allows purification of TSE-binding protein. This purified protein binds specifically to the key element, -301 to -275, and to at least two additional TSE elements clustered in the regulatory region of the hCG beta 5 gene. We conclude that both the alpha- and beta-subunit genes of hCG require the placenta-specific factor TSE-binding protein for expression, providing a mechanism for their coordinate regulation in placental cells.

A new cAMP response element in the transcribed region of the human c-fos gene

In NIH 3T3 cells the c-fos gene is induced rapidly and transiently by cAMP. As shown by the analysis of 3T3 cells stably transfected with promoter mutants of the human c-fos gene this induction does not depend on the dyad symmetry element (position -320 to -300), but involves at least two other non-related sites: an element located around position -60 resembling the cAMP response element of the fibronectin and somatostatin genes (which has been described before), and an element located between positions +18 and +38. Destruction of one or the other element in the c-fos gene reduces cAMP inducibility. The cAMP response of c-fos promoter CAT gene constructs also depends on these elements in transient transfection assays. When cloned in front of the albumin TATA box, both elements independently mediate cAMP inducibility. These elements do not bind the same protein as shown in gel retardation analyses, suggesting that two different cAMP inducible factors mediate the activation of the c-fos gene by cAMP.

Evolution of placenta-specific gene expression: comparison of the equine and human gonadotropin alpha-subunit genes

Primate and equine species are thought to be unique among mammals in synthesizing placental gonadotropin glycoprotein hormones. Human chorionic gonadotropin (CG) and equine pregnant mare's serum gonadotropin (PMSG) are produced in placenta by the specific activation of a glycoprotein hormone alpha-subunit gene and a corresponding beta-subunit gene. The evolutionary mechanisms for the apparently independent acquisition of tissue specificity were investigated by cloning the 5' flanking region of the equine alpha-subunit gene and comparing the DNA elements and trans-acting factors involved in placental expression. We find that though the equine gene is expressed and induced by cAMP, it does not contain the elements known to confer tissue-specific expression to the human gene, the cAMP response element (CRE) and the trophoblast-specific element (TSE), nor does it bind to the trans-acting factors CREB and TSEB. Instead, an additional factor (alpha-ACT) is found which binds to the equine and human, but not the murine, alpha-subunit genes in a region between the positions of the CRE and TSE and confers cAMP responsiveness.

[Adhesive strengths of cast crowns with various types of cements]

In an in vitro study the adhesive strength of sand-blasted castings (gold alloy) was tested on human teeth prepared and finished in different ways. For cementation we used two glass ionomer and one phosphate cement. On the surfaces treated with carbide finishing instruments the force required for separating the crown from the tooth was about 1.9 N/mm2 for Ketac-cem, about 2 N/mm2 for Fuji Ionomer, and about 1.8 N/mm2 for Harvard (a zinc oxide phosphate cement). Compared with this, the values obtained for dentin surfaces pretreated with fine diamonds (red ring) were 1.5 N/mm2 for Ketac-cem, 1.6 N/mm2 for Fuji Ionomer, and 1.9 N/mm2 for Harvard. The measured differences between the various types of cement were statistically not significant.

Isolation and characterization of the human hepatic lipase gene

Overlapping bacterial phage and cosmid genomic clones were isolated spanning an area of approximately 60 kilobases that contains the human hepatic lipase (HL) gene. It is composed of 9 exons spanning approximately 35 kilobases of DNA. The entire coding regions, the 5'-flanking sequences, and the exon-intron junctions were sequenced. The intron positions correspond to those of human lipoprotein lipase and canine pancreatic lipase, supporting the concept that these genes constitute a dispersed gene family of lipases and have evolved by duplication of a common ancestral gene. A region of the HL gene, which displays a significant homology with various other lipolytic enzymes and contains the putative catalytic site serine residue of HL, was encoded by exon 4. A major transcription start site of the human HL gene was located by primer extension analysis, 43 nucleotides upstream of the translation initiation codon. Two possible promoter elements were located 25 and 63 nucleotides upstream of the transcription initiation site: a "TATA" box-like sequence, TAATA, and a sequence found in the promoter region of many liver-specific genes, AGGTTAATTATTAAT. In addition, sequences homologous to glucocorticoid and cAMP-responsive elements were identified in the 5'-nontranscribed region.

Autoregulation of fos: the dyad symmetry element as the major target of repression

Fos and Jun co-operatively repress the fos promoter. Removal of all putative Fos/Jun binding sites from the fos promoter neither obliterates the repression by Fos/Jun in transient cotransfection experiments in NIH3T3 cells nor the turn-off kinetics of serum-induced fos expression in stably transfected NIH3T3 cells. The dyad symmetry element (DSE) suffices to subject a promoter to this type of repression. However, one of the putative Fos/Jun binding sites (-292 to -299 and thus located immediately adjacent to the DSE), determines the very low level of basal expression.

The Fos and Jun/AP-1 proteins are involved in the downregulation of Fos transcription

The low basal expression of Fos and the rapid and effective turn-off of serum induced Fos transcription is due to autoregulation. Fos and Jun/AP-1 protein cooperate in the repression mechanism. Overexpressions of Fos and Jun decrease basal and induced transcription from Fos-CAT constructs and from the endogenous gene in NIH3T3 cells. The introduction into cells of either antisense Fos or antisense Jun sequences leads to elevated basal Fos promoter activity. Gel retardation experiments with synthetic oligonucleotides define two target sequences in the Fos promoter which bind Fos-Jun/AP-1 (centering at about -296 and -60). In vivo competition with these oligonucleotides relieves repression.

Activation of the c-fos gene by UV and phorbol ester: different signal transduction pathways converge to the same enhancer element

In NIH3T3 cells stably transfected with the human c-fos gene, serum, platelet derived growth factor (PDGF), phorbol ester (12-O-tetradecanoyl-phorbol-13-acetate, TPA), ultraviolet irradiation (UV) and 3'-5'-cyclic adenosine monophosphate (cAMP) cause a transient and rapid activation of both the endogenous and the transfected c-fos genes. While serum, TPA, UV and PDGF dependent activation of the gene is severely impaired, when the serum responsive element from position -319 to -300 (SRE, Treisman, 1985) is destroyed, a full response to cAMP is retained. Insertion of a synthetic oligonucleotide corresponding to the SRE element upstream of position -96 restores the responses to TPA and serum, and large parts of the responses to UV and PDGF. The signal transduction chains elicited by UV and TPA are blocked by an inhibitor of protein kinase. Only TPA, however, causes the translocation of protein kinase C to the membrane. UV and TPA treated cells become refractory to a second stimulation by the same agent at 3 or 24 hours after the first treatment. Alternating the agents, however, leads to full responses. In addition, saturating doses of UV and TPA are at least additive. Ca-ionophores severely reduce only UV induced c-fos expression. These data indicate, that different signal transduction pathways elicited by growth promoting agents and by UV induced stress converge onto the same enhancer element.

Replication strategy of human hepatitis B virus

To study the replication strategy of the human hepatitis B virus, the 5' end of the RNA pregenome and the initiation sites of DNA plus and minus strands have been mapped. The RNA pregenome was found to be terminally redundant by 120 nucleotides; it is initiated within the pre-C region and may also function as mRNA for synthesis of the major core protein and the hepatitis B virus reverse transcriptase. The hepatitis B virus DNA minus strand is initiated within the direct repeat sequence DR1, it contains a terminal redundancy of up to eight nucleotides, and its synthesis does not require any template switch. The DNA plus strand is primed by a short oligoribonucleotide probably derived from the 5' end of the RNA pregenome, and its synthesis is initiated close to the direct repeat sequence DR2. For its elongation to pass the discontinuity in the DNA minus strand an intramolecular template switch occurs using the terminal redundancy of this template. Thus, the route of reverse transcription and DNA replication of hepatitis B viruses is fundamentally different from that of retroviruses.

Transcripts and the putative RNA pregenome of duck hepatitis B virus: implications for reverse transcription

Duck hepatitis B virus (DHBV) is a DNA virus that replicates by reverse transcription. We have examined transcripts of DHBV to elucidate mechanisms of gene expression and replication. Three major transcripts were characterized and related to the expression of the genes for the core antigen (DHBcAg), the surface antigen (DHBsAg), and the pre-S/DHBs protein, respectively. They are unspliced and overlap partially since they start at different promoter sites, but they terminate near a common polyadenylation signal. The messenger RNA related to DHBcAg expression is the only major transcript of more than genome length and therefore also represents the putative template for reverse transcription (pregenome). Its structure predicts a strategy of replication of hepatitis B viruses different from that of retroviruses.