526 research outputs found
Modified Bethe-Weizsacker mass formula with isotonic shift and new driplines
Nuclear masses are calculated using the modified Bethe-Weizsacker mass
formula in which the isotonic shifts have been incorporated. The results are
compared with the improved liquid drop model with isotonic shift. Mass excesses
predicted by this method compares well with the microscopic-macroscopic model
while being much more simple. The neutron and proton drip lines have been
predicted using this modified Bethe-Weizsacker mass formula with isotonic
shifts.Comment: 9 pages including 2 figure
The Tamm-Dancoff Approximation as the boson limit of the Richardson-Gaudin equations for pairing
A connection is made between the exact eigen states of the BCS Hamiltonian
and the predictions made by the Tamm-Dancoff Approximation. This connection is
made by means of a parametrised algebra, which gives the exact quasi-spin
algebra in one limit of the parameter and the Heisenberg-Weyl algebra in the
other. Using this algebra to construct the Bethe Ansatz solution of the BCS
Hamiltonian, we obtain parametrised Richardson-Gaudin equations, leading to the
secular equation of the Tamm-Dancoff Approximation in the bosonic limit. An
example is discussed in depth.Comment: Submitted to the proceedings of the Group28 conference
(Newcastle-upon-Tyne, UK). Journal of Physics: Conference Serie
Critical view of WKB decay widths
A detailed comparison of the expressions for the decay widths obtained within
the semiclassical WKB approximation using different approaches to the tunneling
problem is performed. The differences between the available improved formulae
for tunneling near the top and the bottom of the barrier are investigated.
Though the simple WKB method gives the right order of magnitude of the decay
widths, a small number of parameters are often fitted. The need to perform the
fitting procedure remaining consistently within the WKB framework is emphasized
in the context of the fission model based calculations. Calculations for the
decay widths of some recently found super heavy nuclei using microscopic
alpha-nucleus potentials are presented to demonstrate the importance of a
consistent WKB calculation. The half-lives are found to be sensitive to the
density dependence of the nucleon-nucleon interaction and the implementation of
the Bohr-Sommerfeld quantization condition inherent in the WKB approach.Comment: 18 pages, Late
ATLS® and damage control in spine trauma
Substantial inflammatory disturbances following major trauma have been found throughout the posttraumatic course of polytraumatized patients, which was confirmed in experimental models of trauma and in vitro settings. As a consequence, the principle of damage control surgery (DCS) has developed over the last two decades and has been successfully introduced in the treatment of severely injured patients. The aim of damage control surgery and orthopaedics (DCO) is to limit additional iatrogenic trauma in the vulnerable phase following major injury. Considering traumatic brain and acute lung injury, implants for quick stabilization like external fixators as well as decided surgical approaches with minimized potential for additional surgery-related impairment of the patient's immunologic state have been developed and used widely. It is obvious, that a similar approach should be undertaken in the case of spinal trauma in the polytraumatized patient. Yet, few data on damage control spine surgery are published to so far, controlled trials are missing and spinal injury is addressed only secondarily in the broadly used ATLS® polytrauma algorithm. This article reviews the literature on spine trauma assessment and treatment in the polytrauma setting, gives hints on how to assess the spine trauma patient regarding to the ATLS® protocol and recommendations on therapeutic strategies in spinal injury in the polytraumatized patient
Neutron and proton drip lines using the modified Bethe-Weizsacker mass formula
Proton and neutron separation energies have been calculated using the
extended Bethe-Weizsacker mass formula. This modified Bethe-Weizsacker mass
formula describes minutely the positions of all the old and the new magic
numbers. It accounts for the disappearance of some traditional magic numbers
for neutrons and provides extra stability for some new neutron numbers. The
neutron and proton drip lines have been predicted using this extended
Bethe-Weizsacker mass formula. The implications of the proton drip line on the
astrophysical rp-process and of the neutron drip line on the astrophysical
r-process have been discussed.Comment: 5 pages, 2 figure
Platelets activate a pathogenic response to blood-stage Plasmodium infection but not a protective immune response
© 2017 by The American Society of Hematology. Clinical studies indicate that thrombocytopenia correlates with the development of severe falciparum malaria, suggesting that platelets either contribute to control of parasite replication, possibly as innate parasite killer cells or function in eliciting pathogenesis. Removal of platelets by anti-CD41 mAb treatment, platelet inhibition by aspirin, and adoptive transfer of wild-type (WT) platelets to CD40-KO mice, which do not control parasite replication, resulted in similar parasitemia compared with control mice. Human platelets at a physiologic ratio of 1 platelet to 9 red blood cells (RBCs) did not inhibit the in vitro development or replication of blood-stage Plasmodium falciparum. The percentage of Plasmodium-infected (iRBCs) with bound platelets during the ascending parasitemia in Plasmodium chabaudi- and Plasmodium berghei-infected mice and the 48-hour in vitro cycle of P falciparum was <10%. P chabaudi and P berghei iRBCs with apoptotic parasites (TdT1) exhibited minimal platelet binding (<5%), which was similar to nonapoptotic iRBCs. These findings collectively indicate platelets do not kill bloodstage Plasmodium at physiologically relevant effector-to-target ratios.Pchabaudi primary andsecondary parasitemiawassimilar in mice depleted of platelets by mAb-injection just before infection, indicating that activation of the protective immune response does not require platelets. In contrast to the lack of an effect on parasite replication, adoptive transfer ofWTplatelets to CD40-KOmice, which are resistant to experimental cerebral malaria, partially restored experimental cerebral malaria mortality and symptoms in CD40-KO recipients, indicating platelets elicit pathogenesis and platelet CD40 is a key molecule
Der Verbleib Quartärer Ammoniumverbindungen im Boden - Ergebnisse aus Studien mit Modellsubstanzen
Quartäre Alkylammoniumverbindungen (QAAV) sind eine Gruppe amphiphiler organischer Verbindungen, welche weltweit als Tensid und zur Desinfektion, beispielsweise in der Tierhaltung eingesetzt werden. Aufgrund ihres Einsatzes in der Tierhaltung oder als Formulierung in Pflanzenschutzmittel gelangen diese Stoffe mit hoher Wahrscheinlichkeit in Böden. Bislang sind Daten zum Verbleib der QAAVs in Böden in der Literatur allerdings kaum dokumentiert.
Aufgrund des positiv geladenen Stickstoffatoms in ihrer Struktur, sowie bekannter Anwendung der QAAVs in Organotonen, ist von einem Eindringen in die Zwischenschichten aufweitbarer Tonminerale im Boden auszugehen. Eine langsame Desorption aus den Zwischenschichten könnte zu sub-inhibitorischen QAAV-Konzentrationen in der Bodenlösung führen, die zu einer Resistenzgenentwickung und Co-Selektion für Antibiotikaresistenzgene von Mikroorganismen beitragen.
Eine höhere Affinität der Schichtsilikate im Vergleich zu anderen Bodenbestandteilen wird für die Sorption von QAAVs angenommen. Um zu prüfen, in welchem Umfang und mit welcher Rate QAAVs in Zwischenschichten von Tonmineralen wandern, werden Experimente zur Sorptionskinetik in Gegenwart von Smektit (Wyoming-Bentonit) in 8 Stufen im Konzentrationsbereich 0 mmol*g-1 Ton bis 1.5 mmol*g-1 Ton durchgeführt. Basierend auf diesen Ergebnissen wurde in Batch Sorptionsversuchen bei kontrolliertem pH die Affinität der QAAVs zu den Modellsubstanzen Huminsäure(Aldrich), Smektit und Eisenoxid (Goethit) und der Einfluss variabler Ionenstärke auf das Adsorptionsverhalten untersucht. Anschließend sind mit denselben Substanzen Desorptionsexperimente zur Ermittlung von Desorptionskinetiken durchgeführt worden. Das Eindringen von QAAVs in die Zwischenschichten aufweitbarer Tonminerale wurde mittels Röntgendiffraktometrie überprüft.
Die Ergebnisse der Desorptions- und Sorptionsstudien liefern eine Grundlage zum Verständnis für den Verbleib und Transport von QAAVs in Böden
Orbital M1 versus E2 strength in deformed nuclei: A new energy weighted sum rule
Within the unified model of Bohr and Mottelson we derive the following linear
energy weighted sum rule for low energy orbital 1 excitations in even-even
deformed nuclei S_{\rm LE}^{\rm lew} (M_1^{\rm orb}) \cong (6/5) \epsilon
(B(E2; 0^+_1 \rightarrow 2_1^+ K=0)/Z e^2^2) \mu^2_N with B(E2) the E2
strength for the transition from the ground state to the first excited state in
the ground state rotational band, the charge r.m.s. radius squared and
the binding energy per nucleon in the nuclear ground state. It is
shown that this energy weighted sum rule is in good agreement with available
experimental data. The sum rule is derived using a simple ansatz for the
intrinsic ground state wave function that predicts also high energy 1
strength at 2 carrying 50\% of the total moment of the
orbital M1 operator.Comment: REVTEX (3.0), 9 pages, RU924
Citrulline protects mice from experimental cerebral malaria by ameliorating hypoargininemia, urea cycle changes and vascular leak
© 2019 Gramaglia et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Clinical and model studies indicate that low nitric oxide (NO) bioavailability due in part to profound hypoargininemia contributes to cerebral malaria (CM) pathogenesis. Protection against CM pathogenesis may be achieved by altering the diet before infection with Plasmodium falcIParum infection (nutraceutical) or by administering adjunctive therapy that decreases CM mortality (adjunctive therapy). This hypothesis was tested by administering citrulline or arginine in experimental CM (eCM). We report that citrulline injected as prophylaxis immediately post infection (PI) protected virtually all mice by ameliorating (i) hypoargininemia, (ii) urea cycle impairment, and (iii) disruption of blood brain barrier. Citrulline prophylaxis inhibited plasma arginase activity. Parasitemia was similar in citrulline- And vehicle control-groups, indicating that protection from pathogenesis was not due to decreased parasitemia. Both citrulline and arginine administered from day 1 PI in the drinking water significantly protected mice from eCM. These observations collectively indicate that increasing dietary citrulline or arginine decreases eCM mortality. Citrulline injected IP on day 4 PI with quinine-injected IP on day 6 PI partially protected mice from eCM; citrulline plus scavenging of superoxide with pegylated superoxide dismutase and pegylated catalase protected all recIPients from eCM. These findings indicate that ameliorating hypoargininemia with citrulline plus superoxide scavenging decreases eCM mortality
Magic numbers in exotic nuclei and spin-isospin properties of {\it NN} interaction
The magic numbers in exotic nuclei are discussed, and their novel origin is
shown to be the spin-isospin dependent part of the nucleon-nucleon interaction
in nuclei. The importance and robustness of this mechanism is shown in terms of
meson exchange, G-matrix and QCD theories. In neutron-rich exotic nuclei, magic
numbers such as N = 8, 20, etc. can disappear, while N = 6, 16, etc. arise,
affecting the structure of lightest exotic nuclei to nucleosynthesis of heavy
elements.Comment: 4 pages, 3 figures, revte
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