Theory of electron transfer and ionization

The main effort reported is directed toward charge transfer and ionization in high energy atomic collisions. The research may be divided into classical trajectory calculations, quantum - mechanical collision theory, and phenomenological treatments of quantal interference effects in heavy ion collisions

String and M-theory Deformations of Manifolds with Special Holonomy

The R^4-type corrections to ten and eleven dimensional supergravity required by string and M-theory imply corrections to supersymmetric supergravity compactifications on manifolds of special holonomy, which deform the metric away from the original holonomy. Nevertheless, in many such cases, including Calabi-Yau compactifications of string theory and G_2-compactifications of M-theory, it has been shown that the deformation preserves supersymmetry because of associated corrections to the supersymmetry transformation rules, Here, we consider Spin(7) compactifications in string theory and M-theory, and a class of non-compact SU(5) backgrounds in M-theory. Supersymmetry survives in all these cases too, despite the fact that the original special holonomy is perturbed into general holonomy in each case.Comment: Improved discussion of SU(5) holonomy backgrounds. Other minor typos corrected. Latex with JHEP3.cls, 42 page

On the multiplicity of the O-star Cyg OB2 #8A and its contribution to the gamma-ray source 3EG J2033+4118

We present the results of an intensive spectroscopic campaign in the optical waveband revealing that Cyg OB2 #8A is an O6 + O5.5 binary system with a period of about 21.9 d. Cyg OB2 #8A is a bright X-ray source, as well as a non-thermal radio emitter. We discuss the binarity of this star in the framework of a campaign devoted to the study of non-thermal emitters, from the radio waveband to gamma-rays. In this context, we attribute the non-thermal radio emission from this star to a population of relativistic electrons, accelerated by the shock of the wind-wind collision. These relativistic electrons could also be responsible for a putative gamma-ray emission through inverse Compton scattering of photospheric UV photons, thus contributing to the yet unidentified EGRET source 3EG J2033+4118.Comment: 8 pages, 4 figures, conference on "The Multiwavelength Approach to Gamma-Ray Sources", to appear in Ap&S

Glibenclamide in the treatment for gestational diabetes mellitus in a compared study to insulin

OBJECTIVES: To study glibenclamide as a treatment for gestational diabetes mellitus (GDM) and its impact on newborn birth weight and neonatal glycemia as compared to insulin. METHODS: A randomized and open-label clinical trial, conducted from October 1st, 2003 to March 8, 2005. Seventy-two pregnant women with gestational diabetes mellitus requiring drug therapy were randomized and allocated into two groups - insulin and glibenclamide. RESULTS: The general characteristics in both groups were similar, except for the results of the 75 g OGTT, which were higher in the glibenclamide group (p= 0.02). Maternal fasting and postprandial glucose levels presented no difference. Six (18.75%) pregnant women received the maximum dose of glibenclamide with no glycemic control. The birth weight was higher in the group treated with glibenclamide (p= 0.01), and the incidence of macrosomic newborns statistically different (p= 0.01). Neonatal hypoglycemia was more frequent (p= 0.01) in newborns of glibenclamide group, with one single case of persistent hypoglycemia. CONCLUSION: Glibenclamide can be the first line drug for glycemic control in most GDM patients. The birth weight and incidence of hypoglycemia were higher in the glibenclamide group, but with one single case of persistent hypoglycemia that required intravenous infusion of glucose.OBJETIVOS: Estudar a glibenclamida no tratamento do diabete melito gestacional (DMG) e sua repercussão no peso e na glicemia do recém-nascido (RN), em comparação com a insulina. MÉTODOS: Ensaio clínico randomizado e aberto, realizado entre 1º de outubro de 2003 e 8 de março de 2005. Foram sujeitas 72 gestantes com DMG que necessitaram de terapêutica complementar, sendo randomizadas em dois grupos: insulina e glibenclamida. RESULTADOS: As características gerais nos grupos não apresentaram diferença estatística, com exceção dos resultados do TTOG 75 g, que apresentaram valores maiores no grupo da glibenclamida (p= 0,02). As glicemias médias maternas não apresentaram diferença. Seis (18,75%) gestantes atingiram a dose máxima de glibenclamida sem o controle glicêmico. O peso dos RNs foi maior no grupo tratado com glibenclamida (p= 0,01), com diferença na incidência de macrossômico (p= 0,01). A hipoglicemia neonatal estava mais presente (p= 0,01) nos RNs do grupo da glibenclamida, porém com apenas um caso de hipoglicemia persistente. CONCLUSÃO: A glibenclamida pode ser a droga de escolha para tratamento do DMG na maioria das pacientes.Universidade Federal de São Paulo (UNIFESP) EPM Departamento de ObstetríciaMaternidade Darcy VargasUniversidade da Região de JoinvilleUNIFESP, EPM, Depto. de ObstetríciaSciEL

Model for tumour growth with treatment by continuous and pulsed chemotherapy

Peer reviewedPreprin

Primordial magnetic fields and the HI signal from the epoch of reionization

The implication of primordial magnetic-field-induced structure formation for the HI signal from the epoch of reionization is studied. Using semi-analytic models, we compute both the density and ionization inhomogeneities in this scenario. We show that: (a) The global HI signal can only be seen in emission, unlike in the standard $\Lambda$CDM models, (b) the density perturbations induced by primordial fields, leave distinctive signatures of the magnetic field Jeans' length on the HI two-point correlation function, (c) the length scale of ionization inhomogeneities is \la 1 \rm Mpc. We find that the peak expected signal (two-point correlation function) is $\simeq 10^{-4} \rm K^2$ in the range of scales $0.5\hbox{-}3 \rm Mpc$ for magnetic field strength in the range $5 \times 10^{-10} \hbox{-}3 \times 10^{-9} \rm G$. We also discuss the detectability of the HI signal. The angular resolution of the on-going and planned radio interferometers allows one to probe only the largest magnetic field strengths that we consider. They have the sensitivity to detect the magnetic field-induced features. We show that thefuture SKA has both the angular resolution and the sensitivity to detect the magnetic field-induced signal in the entire range of magnetic field values we consider, in an integration time of one week.Comment: 19 pages, 5 figures, to appear in JCA

Guiding the Way to Gamma-Ray Sources: X-ray Studies of Supernova Remnants

Supernova remnants have long been suggested as a class of potential counterparts to unidentified gamma-ray sources. The mechanisms by which such gamma-rays can arise may include emission from a pulsar associated with a remnant, or a variety of processes associated with energetic particles accelerated by the SNR shock. Imaging and spectral observations in the X-ray band can be used to identify properties of the remnants that lead to gamma-ray emission, including the presence of pulsar-driven nebulae, nonthermal X-ray emission from the SNR shells, and the interaction of SNRs with dense surrounding material.Comment: 16 pages, 11 figures, To appear in the proceedings of the workshop: "The Nature of the Unidentified Galactic Gamma-Ray Sources" held at INAOE, Mexico, October 2000, (A.Carraminana, O. Reiner and D. Thompson, eds.

M-theory on eight-manifolds revisited: N=1 supersymmetry and generalized Spin(7) structures

The requirement of ${\cal N}=1$ supersymmetry for M-theory backgrounds of the form of a warped product ${\cal M}\times_{w}X$, where $X$ is an eight-manifold and ${\cal M}$ is three-dimensional Minkowski or AdS space, implies the existence of a nowhere-vanishing Majorana spinor $\xi$ on $X$. $\xi$ lifts to a nowhere-vanishing spinor on the auxiliary nine-manifold $Y:=X\times S^1$, where $S^1$ is a circle of constant radius, implying the reduction of the structure group of $Y$ to $Spin(7)$. In general, however, there is no reduction of the structure group of $X$ itself. This situation can be described in the language of generalized $Spin(7)$ structures, defined in terms of certain spinors of $Spin(TY\oplus T^*Y)$. We express the condition for ${\cal N}=1$ supersymmetry in terms of differential equations for these spinors. In an equivalent formulation, working locally in the vicinity of any point in $X$ in terms of a `preferred' $Spin(7)$ structure, we show that the requirement of ${\cal N}=1$ supersymmetry amounts to solving for the intrinsic torsion and all irreducible flux components, except for the one lying in the $\bf{27}$ of $Spin(7)$, in terms of the warp factor and a one-form $L$ on $X$ (not necessarily nowhere-vanishing) constructed as a $\xi$ bilinear; in addition, $L$ is constrained to satisfy a pair of differential equations. The formalism based on the group $Spin(7)$ is the most suitable language in which to describe supersymmetric compactifications on eight-manifolds of $Spin(7)$ structure, and/or small-flux perturbations around supersymmetric compactifications on manifolds of $Spin(7)$ holonomy.Comment: 24 pages. V2: introduction slightly extended, typos corrected in the text, references added. V3: the role of Spin(7) clarified, erroneous statements thereof corrected. New material on generalized Spin(7) structures in nine dimensions. To appear in JHE