Amenability of algebras of approximable operators

We give a necessary and sufficient condition for amenability of the Banach algebra of approximable operators on a Banach space. We further investigate the relationship between amenability of this algebra and factorization of operators, strengthening known results and developing new techniques to determine whether or not a given Banach space carries an amenable algebra of approximable operators. Using these techniques, we are able to show, among other things, the non-amenability of the algebra of approximable operators on Tsirelson's space.Comment: 20 pages, to appear in Israel Journal of Mathematic

Magnetic fluctuations in frustrated Laves hydrides R(Mn_{1-x}Al_{x})_{2}H_{y}

By neutron scattering, we have studied the spin correlations and spin fluctuations in frustrated Laves hydrides, where magnetic disorder sets in the topologically frustrated Mn lattice. Below the transition towards short range magnetic order, static spin clusters coexist with fluctuating and alsmost uncorrelated spins. The magnetic response shows a complexe lineshape, connected with the presence of the magnetic inhomogeneities. Its analysis shows the existence of two different processes, relaxation and local excitations, for the spin fluctuations below the transition. The paramagnetic fluctuations are discussed in comparison with classical spin glasses, cluster glasses, and non Fermi liquid itinerant magnets

Exponential and moment inequalities for U-statistics

A Bernstein-type exponential inequality for (generalized) canonical U-statistics of order 2 is obtained and the Rosenthal and Hoffmann-J{\o}rgensen inequalities for sums of independent random variables are extended to (generalized) U-statistics of any order whose kernels are either nonnegative or canonicalComment: 22 page

Covering convex bodies by cylinders and lattice points by flats

In connection with an unsolved problem of Bang (1951) we give a lower bound for the sum of the base volumes of cylinders covering a d-dimensional convex body in terms of the relevant basic measures of the given convex body. As an application we establish lower bounds on the number of k-dimensional flats (i.e. translates of k-dimensional linear subspaces) needed to cover all the integer points of a given convex body in d-dimensional Euclidean space for 0<k<d

Erythropoietin reduces neuronal cell death and hyperalgesia induced by peripheral inflammatory pain in neonatal rats

Painful stimuli during neonatal stage may affect brain development and contribute to abnormal behaviors in adulthood. Very few specific therapies are available for this developmental disorder. A better understanding of the mechanisms and consequences of painful stimuli during the neonatal period is essential for the development of effective therapies. In this study, we examined brain reactions in a neonatal rat model of peripheral inflammatory pain. We focused on the inflammatory insult-induced brain responses and delayed changes in behavior and pain sensation. Postnatal day 3 pups received formalin injections into the paws once a day for 3 days. The insult induced dysregulation of several inflammatory factors in the brain and caused selective neuronal cell death in the cortex, hippocampus and hypothalamus. On postnatal day 21, rats that received the inflammatory nociceptive insult exhibited increased local cerebral blood flow in the somatosensory cortex, hyperalgesia, and decreased exploratory behaviors. Based on these observations, we tested recombinant human erythropoietin (rhEPO) as a potential treatment to prevent the inflammatory pain-induced changes. rhEPO treatment (5,000 U/kg/day, i.p.), coupled to formalin injections, ameliorated neuronal cell death and normalized the inflammatory response. Rats that received formalin plus rhEPO exhibited normal levels of cerebral blood flow, pain sensitivity and exploratory behavior. Treatment with rhEPO also restored normal brain and body weights that were reduced in the formalin group. These data suggest that severe inflammatory pain has adverse effects on brain development and rhEPO may be a possible therapy for the prevention and treatment of this developmental disorder

Measurement of the cross-section ratio sigma_{psi(2S)}/sigma_{J/psi(1S)} in deep inelastic exclusive ep scattering at HERA

The exclusive deep inelastic electroproduction of $\psi(2S)$ and $J/\psi(1S)$ at an $ep$ centre-of-mass energy of 317 GeV has been studied with the ZEUS detector at HERA in the kinematic range $2 < Q^2 < 80$ GeV$^2$, $30 < W < 210$ GeV and $|t| < 1$ GeV$^2$, where $Q^2$ is the photon virtuality, $W$ is the photon-proton centre-of-mass energy and $t$ is the squared four-momentum transfer at the proton vertex. The data for $2 < Q^2 < 5$ GeV$^2$ were taken in the HERA I running period and correspond to an integrated luminosity of 114 pb$^{-1}$. The data for $5 < Q^2 < 80$ GeV$^2$ are from both HERA I and HERA II periods and correspond to an integrated luminosity of 468 pb$^{-1}$. The decay modes analysed were $\mu^+\mu^-$ and $J/\psi(1S) \,\pi^+\pi^-$ for the $\psi(2S)$ and $\mu^+\mu^-$ for the $J/\psi(1S)$. The cross-section ratio $\sigma_{\psi(2S)}/\sigma_{J/\psi(1S)}$ has been measured as a function of $Q^2, W$ and $t$. The results are compared to predictions of QCD-inspired models of exclusive vector-meson production.Comment: 24 pages, 8 figure

Multijet production in neutral current deep inelastic scattering at HERA and determination of α_{s}

Multijet production rates in neutral current deep inelastic scattering have been measured in the range of exchanged boson virtualities 10 5 GeV and –1 < η_{LAB}^{jet} < 2.5. Next-to-leading-order QCD calculations describe the data well. The value of the strong coupling constant α_{s} (M_{z}), determined from the ratio of the trijet to dijet cross sections, is α_{s} (M_{z}) = 0.1179 ± 0.0013 (stat.)_{-0.0046}^{+0.0028}(exp.)_{-0.0046}^{+0.0028}(th.)

Measurement of neutral current e+/-p cross sections at high Bjorken x with the ZEUS detector

The neutral current e+/-p cross section has been measured up to values of Bjorken x of approximately 1 with the ZEUS detector at HERA using an integrated luminosity of 187 inv. pb of e-p and 142 inv. pb of e+p collisions at sqrt(s) = 318GeV. Differential cross sections in x and Q2, the exchanged boson virtuality, are presented for Q2 geq 725GeV2. An improved reconstruction method and greatly increased amount of data allows a finer binning in the high-x region of the neutral current cross section and leads to a measurement with much improved precision compared to a similar earlier analysis. The measurements are compared to Standard Model expectations based on a variety of recent parton distribution functions.Comment: 39 pages, 9 figure

Lepkość krwi w chorobach układu krążenia ze szczególnym uwzględnieniem kardiologicznego zespołu X

Lepkość, nazywana również tarciem wewnętrznym, jest miarą oporu stawianego przez ciecze podczas wzajemnego przesuwania się warstw płynu. Krew pełna jest powszechnie uznawana za płyn nienewtonowski, którego lepkość nie jest stała, a jest funkcją prędkości przepływu. Lepkość krwi pełnej zależy od liczby i właściwości erytrocytów (agregacji, deformacji) oraz od lepkości osocza. Zmiany lepkości krwi opisywano w chorobie niedokrwiennej serca, zawale serca, nagłej śmierci sercowej, hiperlipoproteinemii, miażdżycy tętnic obwodowych, nadciśnieniu tętniczym. Turczyński i wsp. wykazali istotnie podwyższone wartości lepkości krwi pełnej i osocza u osób z kardiologicznym zespołem X w porównaniu z grupą kontrolną osób zdrowych. Kardiologiczny zespół X stanowi istotny problem kliniczny i epidemiologiczny. Występuje u 10&#8211;30% osób poddanych koronarografii. Patomechanizm jego objawów nie został wyjaśniony. Czynnikiem współodpowiedzialnym za zaburzenia mikrokrążenia w tym zespole może być zmieniona lepkość krwi. W zespole X występują zaburzenia funkcji śródbłonka, co może upośledzać mechanizmy zmniejszania lepkości krwi. Ponadto częściej niż w populacji ogólnej stwierdza się podwyższone stężenie fibrynogenu i zaburzenia gospodarki lipidowej, co pozwala przypuszczać, że zmienione są właściwości reologiczne krwi. Możliwe, że hiperlipidemia, zwiększona lepkość krwi i zmniejszona rezerwa wieńcowa są głównymi przyczynami nawracających epizodów niedokrwienia u pacjentów z omawianym zespołem. Właściwości reologiczne krwi mają duże znaczenie w chorobach układu sercowo-naczyniowego. Dokładne ich poznanie u osób z kardiologicznym zespołem X może wyjaśnić jego patogenezę oraz mieć istotne znaczenie kliniczne. Różnice lepkości krwi w populacji osób zdrowych są nieznaczne, co czyni ten parametr przydatnym w ocenie klinicznej. W artykule omówiono prawa fizyki dotyczące lepkości cieczy, mechanizmy regulujące lepkość krwi oraz choroby układu krążenia, w których lepkość krwi jest zmieniona. (Folia Cardiol. 2005; 12: 465&#8211;470