Fragmentation of Single-Particle Strength around the Doubly Magic Nucleus

Spectroscopic factors of neutron-hole and proton-hole states in ^{131}Sn and ^{131}In, respectively, were measured using one-nucleon removal reactions from doubly magic ^{132}Sn at relativistic energies. For ^{131}In, a 2910(50)-keV γ ray was observed for the first time and tentatively assigned to a decay from a 5/2^{-} state at 3275(50) keV to the known 1/2^{-} level at 365 keV. The spectroscopic factors determined for this new excited state and three other single-hole states provide first evidence for a strong fragmentation of single-hole strength in ^{131}Sn and ^{131}In. The experimental results are compared to theoretical calculations based on the relativistic particle-vibration coupling model and to experimental information for single-hole states in the stable doubly magic nucleus ^{208}Pb.

Approaching the Gamow Window with Stored Ions: Direct Measurement of

We report the first measurement of low-energy proton-capture cross sections of ^{124}Xe in a heavy-ion storage ring. ^{124}Xe^{54+} ions of five different beam energies between 5.5 and 8 AMeV were stored to collide with a windowless hydrogen target. The ^{125}Cs reaction products were directly detected. The interaction energies are located on the high energy tail of the Gamow window for hot, explosive scenarios such as supernovae and x-ray binaries. The results serve as an important test of predicted astrophysical reaction rates in this mass range. Good agreement in the prediction of the astrophysically important proton width at low energy is found, with only a 30% difference between measurement and theory. Larger deviations are found above the neutron emission threshold, where also neutron and γ widths significantly impact the cross sections. The newly established experimental method is a very powerful tool to investigate nuclear reactions on rare ion beams at low center-of-mass energies.

Quasifree (p, 2p) Reactions on Oxygen Isotopes: Observation of Isospin Independence of the Reduced Single-Particle Strength.

Quasifree one-proton knockout reactions have been employed in inverse kinematics for a systematic study of the structure of stable and exotic oxygen isotopes at the R^{3}B/LAND setup with incident beam energies in the range of 300-450 MeV/u. The oxygen isotopic chain offers a large variation of separation energies that allows for a quantitative understanding of single-particle strength with changing isospin asymmetry. Quasifree knockout reactions provide a complementary approach to intermediate-energy one-nucleon removal reactions. Inclusive cross sections for quasifree knockout reactions of the type ^{A}O(p,2p)^{A-1}N have been determined and compared to calculations based on the eikonal reaction theory. The reduction factors for the single-particle strength with respect to the independent-particle model were obtained and compared to state-of-the-art ab initio predictions. The results do not show any significant dependence on proton-neutron asymmetry.

Strong Neutron Pairing in core+4n Nuclei.

The emission of neutron pairs from the neutron-rich N=12 isotones ^{18}C and ^{20}O has been studied by high-energy nucleon knockout from ^{19}N and ^{21}O secondary beams, populating unbound states of the two isotones up to 15 MeV above their two-neutron emission thresholds. The analysis of triple fragment-n-n correlations shows that the decay ^{19}N(-1p)^{18}C^{*}→^{16}C+n+n is clearly dominated by direct pair emission. The two-neutron correlation strength, the largest ever observed, suggests the predominance of a ^{14}C core surrounded by four valence neutrons arranged in strongly correlated pairs. On the other hand, a significant competition of a sequential branch is found in the decay ^{21}O(-1n)^{20}O^{*}→^{18}O+n+n, attributed to its formation through the knockout of a deeply bound neutron that breaks the ^{16}O core and reduces the number of pairs.

A Poroelastic Fluid/Structure-Interaction Model of Cerebrospinal Fluid Dynamics in the Cord With Syringomyelia and Adjacent Subarachnoid-Space Stenosis.

An existing axisymmetric fluid/structure-interaction (FSI) model of the spinal cord, pia mater, subarachnoid space, and dura mater in the presence of syringomyelia and subarachnoid-space stenosis was modified to include porous solids. This allowed investigation of a hypothesis for syrinx fluid ingress from cerebrospinal fluid (CSF). Gross model deformation was unchanged by the addition of porosity, but pressure oscillated more in the syrinx and the subarachnoid space below the stenosis. The poroelastic model still exhibited elevated mean pressure in the subarachnoid space below the stenosis and in the syrinx. With realistic cord permeability, there was slight oscillatory shunt flow bypassing the stenosis via the porous tissue over the syrinx. Weak steady streaming flow occurred in a circuit involving craniocaudal flow through the stenosis and back via the syrinx. Mean syrinx volume was scarcely altered when the adjacent stenosis bisected the syrinx, but increased slightly when the syrinx was predominantly located caudal to the stenosis. The fluid content of the tissues over the syrinx oscillated, absorbing most of the radial flow seeping from the subarachnoid space so that it did not reach the syrinx. To a lesser extent, this cyclic swelling in a boundary layer of cord tissue just below the pia occurred all along the cord, representing a mechanism for exchange of interstitial fluid (ISF) and cerebrospinal fluid which could explain recent tracer findings without invoking perivascular conduits. The model demonstrates that syrinx volume increase is possible when there is subarachnoid-space stenosis and the cord and pia are permeable.

First Measurement of Several ß-Delayed Neutron Emitting Isotopes Beyond N=126.

The ß-delayed neutron emission probabilities of neutron rich Hg and Tl nuclei have been measured together with ß-decay half-lives for 20 isotopes of Au, Hg, Tl, Pb, and Bi in the mass region N≳126. These are the heaviest species where neutron emission has been observed so far. These measurements provide key information to evaluate the performance of nuclear microscopic and phenomenological models in reproducing the high-energy part of the ß-decay strength distribution. This provides important constraints on global theoretical models currently used in r-process nucleosynthesis.

First observation of the unbound nucleus 15Ne.

We report on the first observation of the unbound proton-rich nucleus 15Ne. Its ground state and first excited state were populated in two-neutron knockout reactions from a beam of 500 MeV/u 17Ne. The 15Ne ground state is found to be unbound by 2.522(66) MeV. The decay proceeds directly to 13O with simultaneous two-proton emission. No evidence for sequential decay via the energetically allowed 2- and 1- states in 14F is observed. The 15Ne ground state is shown to have a strong configuration with two protons in the (sd) shell around 13O with a 63(5)% (1s1/2)2 component.

Measurement of the dipole polarizability of the unstable neutron-rich nucleus 68Ni.

The E1 strength distribution in 68Ni has been investigated using Coulomb excitation in inverse kinematics at the R3B-LAND setup and by measuring the invariant mass in the one- and two-neutron decay channels. The giant dipole resonance and a low-lying peak (pygmy dipole resonance) have been observed at 17.1(2) and 9.55(17) MeV, respectively. The measured dipole polarizability is compared to relativistic random phase approximation calculations yielding a neutron-skin thickness of 0.17(2) fm. A method and analysis applicable to neutron-rich nuclei has been developed, allowing for a precise determination of neutron skins in nuclei as a function of neutron excess.

Suppression of complex fingerlike patterns at the interface between air and a viscous fluid by elastic membranes.

Growth of complex dendritic fingers at the interface of air and a viscous fluid in the narrow gap between two parallel plates is an archetypical problem of pattern formation. We find a surprisingly effective means of suppressing this instability by replacing one of the plates with an elastic membrane. The resulting fluid-structure interaction fundamentally alters the interfacial patterns that develop and considerably delays the onset of fingering. We analyze the dependence of the instability on the parameters of the system and present scaling arguments to explain the experimentally observed behavior.

[Evaluation of prescription practices of long acting injectable risperidone in French hospitals]. / Enquête des prescriptions de rispéridone injectable à libération prolongée dans neuf centres hospitaliers du réseau PIC.

INTRODUCTION: Atypical antipsychotics or antipsychotics of second generation are still recommended by guidelines for primary use in the treatment of psychotic disorders because of their better neurologic safety and efficacy. However, they require daily dosing, thus compromising their overall efficacy whereas conventional depot neuroleptics provide constant pharmacologic treatment but induce extrapyramidal adverse effects and poor efficacy on negative symptoms. Long acting injectable risperidone (LAIR) is the first long-acting second-generation antipsychotic. Registered in October 2003 and launched in March 2005 in France thanks to Kane et al.'s and Fleischhacker et al.'s reference studies, it was supposed to provide the advantages of conventional long acting formulations of antipsychotics over those of an atypical agent. OBJECTIVES AND METHODS: The aims of this study, with the description of the prescription practices of LAIR in naturalistic conditions, were to assess the place of this new drug in psychotic medication, with the efficiency value measured by treatment discontinuation rate and analysis of the reasons for discontinuation, and to assess whether the prescriptions practices are or not in adequacy with guidelines and reglementation. In June 2005, we conducted a one-year naturalistic non-randomised open-label study in nine French psychiatric hospitals, members of the PIC network: were included all the patients who received LAIR every 2 weeks, between July 1st 2005 and November 30th 2005. RESULTS: Prescriptions of 216 patients were examined for 1 year. LAIR was used off label for 15% of the patients. Ninety-two percent of patients were hospitalized at the beginning of the treatment while 72% of the treated patients had dropped out one year after the first injection. Regarding the nature of previous antipsychotic treatments prescribed in the last three months before the first injection of LAIR: 31% patients had received a first generation antipsychotic, half of which had received a depot antipsychotic of first generation and 69% had received a second-generation antipsychotic, among which half had received oral risperidone. The principal reason noted by the clinicians for starting the new formulation was non-observance with anterior treatments. However, oral antipsychotic treatment preceding the first injection was used less than 4 weeks for one third of the patients. When this treatment was oral risperidone, average posology at the first injection was 6.7 ± 2.4 mg per day; it was 7.4 ± 2.1 mg per day for the patients who received the higher dose of LAIR (50 mg/2 weeks). So, it seems that some patients were not sufficiently stabilized by their antipsychotic before the beginning of the long acting treatment. The result was a significant rate of treatment discontinuations (53%) in the following year, principally caused by the withdrawal of the patient's consent and an insufficient response to treatment. CONCLUSION: This investigation provided the opportunity to analyze the prescriptions of a new formulation drug in routine clinical practice. It confirms the need for respecting the authorized indications and the recommendations of good use of a drug to avoid the failures of treatment and also the importance of the role of the pharmacist in recalling it to the physicians.

Discovery of highly excited long-lived isomers in neutron-rich hafnium and tantalum isotopes through direct mass measurements.

A study of cooled ¹97Au projectile-fragmentation products has been performed with a storage ring. This has enabled metastable nuclear excitations with energies up to 3 MeV, and half-lives extending to minutes or longer, to be identified in the neutron-rich nuclides ¹8³(,)¹84(,)¹86Hf and ¹86(,)¹87Ta. The results support the prediction of a strongly favored isomer region near neutron number 116.

Perioperative anxiety and length of hospital stay after caesarean section - A cohort study.

OBJECTIVE: The caesarean section is one of the most frequently performed surgeries. Due to growing economic challenges, hospitals are encouraged to improve their cost-efficiency. One factor that influences hospital costs of caesarean sections is a prolonged hospital stay. STUDY DESIGN: The aim of the current prospective study was to investigate psychosocial factors, with an emphasis on anxiety, and sociodemographic factors that are associated with longer hospital stay after caesarean sections with no medical complications. Data of 195 women who gave birth by caesarean section was analyzed. As possible predictors anxiety levels measured pre-, peri- and postoperative as well as age, parity (primiparous/multiparous), repeated caesarean (yes/no), BMI (<30/ ≥30), STAI-Trait scores, duration of surgery, PH arterial and Apgar 5 min. were entered into a backward linear regression with duration of hospital stay as the dependent factor. RESULTS: The analysis revealed that higher age, primiparity as well as higher anxiety scores during the postoperative phase are significant factors associated with prolonged hospital stay. The significant model explains 22.1 % of the variance. CONCLUSION: The results should sensitize the medical team to these risk factors in order to improve patients' recovery and shorten hospital stays.

Comparing the course of anxiety in women receiving their first or repeated caesarean section: A prospective cohort study.

BACKGROUND: Around 30% of births are through caesarean section and repetition rates for receiving a caesarean section are high. AIM: The aim of the prospective study was to compare the course of anxiety in women undergoing their first caesarean section and women experiencing a repeated caesarean section. PARTICIPANTS: 304 women with an indication for an elective caesarean section took part. 155 received their first caesarean section and 149 received a repeated caesarean section. METHODS: In order to measure the course of anxiety on the day of the caesarean section subjective anxiety levels were measured and saliva samples for cortisol determination were taken at admission, during skin closure and two hours after the surgery. Blood pressure and heart rate were documented at skin incision and skin closure. RESULTS: Women experiencing their first caesarean section displayed significantly higher anxiety levels compared to women with a repeated caesarean section. Scores of the STAI-State and visual analogue scale for anxiety differed significantly at admission (p=.006 and p<.001) and heart rate and alpha amylase levels were significantly higher at skin closure (p=.027 and p=.029). CONCLUSION: The results show that previous experience with a caesarean section has a soothing effect. The study aims to sensitize surgeons, anesthetists, nurses and midwives when treating women receiving a caesarean section and encourage them to incorporate soothing interventions, especially for women receiving their first caesarean section to reduce anxiety levels and consequently improve postoperative recovery and patients' satisfaction.

Polygynous supercolonies of the acacia-ant Pseudomyrmex peperi, an inferior colony founder.

In ant-plant protection mutualisms, plants provide nesting space and nutrition to defending ants. Several plant-ants are polygynous. Possessing more than one queen per colony can reduce nestmate relatedness and consequently the inclusive fitness of workers. Here, we investigated the colony structure of the obligate acacia-ant Pseudomyrmex peperi, which competes for nesting space with several congeneric and sympatric species. Pseudomyrmex peperi had a lower colony founding success than its congeners and thus, appears to be competitively inferior during the early stages of colony development. Aggression assays showed that P. peperi establishes distinct, but highly polygynous supercolonies, which can inhabit large clusters of host trees. Analysing queens, workers, males and virgin queens from two supercolonies with eight polymorphic microsatellite markers revealed a maximum of three alleles per locus within a colony and, thus, high relatedness among nestmates. Colonies had probably been founded by one singly mated queen and supercolonies resulted from intranidal mating among colony-derived males and daughter queens. This strategy allows colonies to grow by budding and to occupy individual plant clusters for time spans that are longer than an individual queen's life. Ancestral states reconstruction indicated that polygyny represents the derived state within obligate acacia-ants. We suggest that the extreme polygyny of Pseudomyrmex peperi, which is achieved by intranidal mating and thereby maintains high nestmate relatedness, might play an important role for species coexistence in a dynamic and competitive habitat.

Cell-cycle differences of HL-60 leukemia cells fractionated by centrifugal elutriation.

HL-60 leukemia cells were fractionated into G1 and S/G2 populations using a rapid centrifugal elutriation technique, and studied for differences between the cell-cycle phases. The G1 fraction was found to contain smaller cells with a sedimentation velocity of 7 mm/h. The S/G2 fraction consisted of larger cells with a sedimentation velocity of 125 mm/h. The latter fraction was found to have a peak level of the enzyme (2'-5')An-binding protein, as compared to the G1 fraction, indicating a possible role for (2'-5')An-binding protein and its products in the growth regulation of these leukemic cells. In addition, cytofluorometric analysis of fractionated HL-60 cells indicates that elutriation is an effective fractionation method, rapidly yielding large numbers of cells for study, without the use of chemical treatments.

Vascular endothelial growth factor (VEGF) stimulates monocyte migration through endothelial monolayers via increased integrin expression.

Monocytes play an important role in collateral vessel formation (arteriogenesis) by attaching to activated endothelium and by invading the walls of innate collateral vessels where they produce growth factors. Previous studies have demonstrated that this process can be promoted by several chemokines and growth factors. In this study we examined the interaction between monocytes and endothelium under stimulation of the angiogenic agent vascular endothelial growth factor (VEGF). We report here the novel finding that VEGF stimulates the expression of the alphaL-, alphaM- and beta2-integrin monomers. In functional assays and by using neutralizing antibodies it was shown that VEGF stimulates adhesion of monocytes to human umbilical vein endothelial cells (HUVEC), and increased transmigration through endothelial monolayers is dependent on interaction of monocyte beta2-integrins with its endothelial counter ligand ICAM-1. Based on these in vitro data we hypothesize that the positive effect of VEGF on arteriogenesis may involve monocyte activation.

Iron intake and iron nutritional status of infants fed iron-fortified beikost with meat.

We compared iron intake and iron nutritional status of two groups of healthy term infants who received meat-containing baby foods fortified with ferrous sulphate (2 mg Fe/100 g). One group received an Fe-fortified formula (1.6 mg Fe/100 kcal) and the other a nonfortified formula. Fe intake of the group fed the nonfortified formula was significantly lower (p less than 0.0001). These infants received Fe mainly from fortification Fe with beikost (75-86%) and less than 10% met the recommended intake of 1 mg.kg-1.d-1; whereas 80-85% of the infants fed the Fe-fortified formula did. Hb, Hct, FEP, and ferritin were similar in both groups with the exception of lower ferritin values at age 365 d (p less than 0.05) in the group fed the nonfortified formula. No infant had hemoglobin less than 100 g/L. We conclude that regular consumption of commercially prepared Fe-fortified beikost with meat prevents most healthy term infants from Fe deficiency even if Fe intake is substantially below the recommended intake.

Antigen handling in ageing. III. Age-related changes in antigen handling by liver parenchymal and nonparenchymal cells.

This is a continuation of our earlier studies on antigen handling and the ageing process which have shown the liver to be a major site of antigen retention in the body. This paper reports on the uptake and cellular distribution in relatively pure isolates of the principal cell types of the liver of [35S]sulfanilate-azo-bovine serum albumin (35S-BSA) injected into F-344 rats of ages 4, 12 and 28 months. In all three cell types [hepatocytes (H), Kupffer cells (K) and endothelial cells (E)] antigen retention peaks in the 12-month age class and then exhibits a significant decline in the 28-month age class; K and E cells retain more antigen per cell than do H cells. All three cell types metabolize antigen to nucleopeptides and this transformed antigen is immunologically active; K and E cells metabolize antigen to nucleopeptides more effectively than do H cells. A significant age-related difference is found when nucleopeptides from either H, K or E cells are used to stimulate an antigen-specific lymphoproliferative response in vitro: nucleopeptides from 4-month and 12-month rats stimulate the proliferation of lymphocytes to a significantly higher degree than do nucleopeptides from 28-month old rats. The experiments therefore identify in all three cell populations an age-related defect in antigen uptake and in metabolism of antigen to bioactive nucleopeptides, and they demonstrate that the nonparenchymal cells are more effective in antigen retention and in metabolism of antigen to nucleopeptides than are parenchymal cells. Further, the experiments support the thesis that the liver must be considered to be a principal part of the total immune system, its role much more fundamental than heretofore recognized.

GM-CSF: a strong arteriogenic factor acting by amplification of monocyte function.

We investigated the role of the colony stimulating factor for monocytes (GM-CSF) to test the hypothesis whether prolongation of the monocyte's life cycle will support arteriogenesis (rapid growth of preexisting collateral arteries). This appeared logical in view of our discovery that circulating monocytes play an important part in the positive remodeling of small preexisting arterioles into arteries to compensate for arterial occlusions (arteriogenesis) and especially following our findings that MCP-1 markedly increases the speed of arteriogenesis. The continuous infusion of GM-CSF for 7 days into the proximal stump of the acutely occluded femoral artery of rabbits by osmotic minipump produced indeed a marked arteriogenic response as demonstrated by an increase (2-fold) in number and size of collateral arteries on postmortem angiograms and by the increase of maximal blood flow during vasodilation measured in vivo by blood pump perfusion of the hindquarter (5-fold). When GM-CSF and MCP-1 were simultaneously infused the effects on arteriogenesis were additive on angiograms as well as on conductance. GM-CSF was also able to widen the time window of MCP-1 activity: MCP-1 treatment alone was ineffective when given after the third week following occlusion. When administered together with GM-CSF about 80% of normal maximal conductance of the artery that was replaced by collaterals were achieved, a result that was not reached before by any other experimental treatment. Experiments with cells isolated from treated animals showed that monocyte apoptosis was markedly reduced. In addition we hypothesize that GM-CSF may aid in releasing pluripotent monocyte (stem-) cells from the bone marrow into the circulation. In contrast to MCP-1, GM-CSF showed no activity on monocyte transmigration through- and also no influence on monocyte adhesion to cultured endothelial cells. In conclusion we have discovered a new function of the hemopoietic stem cell factor GM-CSF, which is also a powerful arteriogenic peptide that acts via prolongation of the life cycle of monocytes/macrophages.

Anion-dependent dimerization of a guanidiniocarbonyl pyrrole cation in DMSO.

With spherical counteranions such as chloride or hexafluorophosphate, the glycine-derived guanidiniocarbonyl pyrrole cation 1 self-assembles into discrete dimers in DMSO, as can be seen by NMR and ESI mass spectral analysis. According to concentration- and temperature-dependent NMR studies, the dimerization is endothermic and therefore entropy driven. Molecular modeling suggests that the dimers are held together by hydrogen bonding in combination with pi-pi interactions. In the presence of picrate anions, dimerization of cation 1 does not occur, probably due to the formation of pi-stacked ion pairs.