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Central venous access devices (CVADs) aid in the delivery of nutritional support, infusion therapy, and hemodialysis. Maintaining continuous flow through these devices is challenging, because they are susceptible to complications such as thrombi occlusion. Therefore, CVADs may require treatment with anticoagulant or thrombolytic agents. Using these agents as locking solutions has been widely investigated; however, few publications have described the compatibility of the therapeutic with the CVAD itself. The objective of this investigation was to evaluate the in vitro stability and compatibility of a thrombolytic biologic agent, tenecteplase, with various CVAD materials. Tenecteplase was reconstituted to 1 mg/mL with either sterile water for injection or bacteriostatic water for injection (0.9% benzyl alcohol) then incubated in glass vials, polysulfone/silicone vascular access ports, and polyurethane or silicone catheters for up to 96 hours. Biochemical assays including protein monomer, protein one-chain, and in vitro bioactivity were used to assess tenecteplase's compatibility with the investigated diluents and materials every 24 hours. Antimicrobial testing was also performed for up to 28 days on bacteriostatic water for injection-reconstituted samples only. Our results showed tenecteplase to be compatible with both types of diluents (in glass vials) and catheters for up to 72 hours. Furthermore, tenecteplase was compatible with the polysulfone/silicone vascular access ports for up to 24 hours. Finally, bacteriostatic water for injection-reconstituted tenecteplase effectively met USP criteria for the inhibition of growth of micro-organisms. This study serves as an example of a best practice to evaluate the in vitro stability and compatibility of a biologic agent with CVAD materials.

We give three interpretations of the number $b$ of orbits of the Borel subgroup of upper triangular matrices on the variety $\ms{X}$ of complete quadrics. First, we show that $b$ is equal to the number of standard Young tableaux on skew-diagrams. Then, we relate $b$ to certain values of a modified Hermite polynomial. Third, we relate $b$ to a certain cell decomposition on $\ms{X}$ previously studied by De Concini, Springer, and Strickland. Using these, we give asymptotic estimates for $b$ as the dimension of the quadrics increases., Comment: We revised the manuscript

High-dose chemotherapy with autologous stem cell rescue (HDC/SCR) has produced responses and prolonged survival for some children with recurrent brain tumors, but is associated with considerable morbidity and mortality. A Phase I trial of two cycles of HDC/SCR for recurrent brain tumors in children was performed to determine the maximum tolerated doses for a novel regimen.Two cycles of HDC/SCR were given. Cycle 1 included thiotepa and carmustine given on days -5, -4, and -3. Four to six weeks later, patients received cycle 2 which included thiotepa and carboplatin given on days -5, -4, and -3. Autologous peripheral blood stem cells (PBSC) were infused on day 0 of each cycle.Thirty-two patients were treated and 25 patients received both cycles of HDC/SCR. Common toxicities included mucositis, emesis, diarrhea, anorexia, and pancytopenia. Eight of 32 (25%) assessable children died from regimen-related toxicity. Pulmonary failure occurred in seven patients. Seven patients had grade 3-4 neurotoxicity. The 3-year event-free survival (EFS) was 25%.We determined the maximum tolerated regimen to be thiotepa 600 mg/m(2) and carmustine 300 mg/m(2) followed by thiotepa 600 mg/m(2) and carboplatin 1,200 mg/m(2) . Pulmonary toxicity was considerable. The toxic death rate was similar to other trials of HDC/SCR for children with recurrent brain tumors performed during the same time period. The regimen resulted in prolonged time to progression for a significant number of patients and long-term survival for some patients with recurrent medulloblastoma and rhabdoid tumor.

We revisit the issue of relaxation to thermal equilibrium in the so-called "sheet model", i.e., particles in one dimension interacting by attractive forces independent of their separation. We show that this relaxation may be very clearly detected and characterized by following the evolution of order parameters defined by appropriately normalized moments of the phase space distribution which probe its entanglement in space and velocity coordinates. For a class of quasi-stationary states which result from the violent relaxation of rectangular waterbag initial conditions, characterized by their virial ratio R_0, we show that relaxation occurs on a time scale which (i) scales approximately linearly in the particle number N, and (ii) shows also a strong dependence on R_0, with quasi-stationary states from colder initial conditions relaxing much more rapidly. The temporal evolution of the order parameter may be well described by a stretched exponential function. We study finally the correlation of the relaxation times with the amplitude of fluctuations in the relaxing quasi-stationary states, as well as the relation between temporal and ensemble averages., 37 pages, 24 figures; some additional discussion of previous literature and other minor modifications, final published version

We consider the statistical properties of the gravitational field F in an infinite one-dimensional homogeneous Poisson distribution of particles, using an exponential cut-off of the pair interaction to control and study the divergences which arise. Deriving an exact analytic expression for the probability density function (PDF) P(F), we show that it is badly defined in the limit in which the well known Holtzmark distribution is obtained in the analogous three-dimensional case. A well defined P(F) may, however, be obtained in the infinite range limit by an appropriate renormalization of the coupling strength, giving a Gaussian form. Calculating the spatial correlation properties we show that this latter procedure has a trivial physical meaning. Finally we calculate the PDF and correlation properties of differences of forces (at separate spatial points), which are well defined without any renormalization. We explain that the convergence of these quantities is in fact sufficient to allow a physically meaningful infinite system limit to be defined for the clustering dynamics from Poissonian initial conditions., 9 pages, minor changes, final version published in Phys. Rev. E

"Quasi-stationary" states are approximately time-independent out of equilibrium states which have been observed in a variety of systems of particles interacting by long-range interactions. We investigate here the conditions of their occurrence for a generic pair interaction V(r \rightarrow \infty) \sim 1/r^a with a > 0, in d>1 dimensions. We generalize analytic calculations known for gravity in d=3 to determine the scaling parametric dependences of their relaxation rates due to two body collisions, and report extensive numerical simulations testing their validity. Our results lead to the conclusion that, for a < d-1, the existence of quasi-stationary states is ensured by the large distance behavior of the interaction alone, while for a > d-1 it is conditioned on the short distance properties of the interaction, requiring the presence of a sufficiently large soft-core in the interaction potential., 5 pages, 3 figures; final version to appear in Phys. Rev. Lett

We formalize a classification of pair interactions based on the convergence properties of the {\it forces} acting on particles as a function of system size. We do so by considering the behavior of the probability distribution function (PDF) P(F) of the force field F in a particle distribution in the limit that the size of the system is taken to infinity at constant particle density, i.e., in the "usual" thermodynamic limit. For a pair interaction potential V(r) with V(r) \rightarrow \infty) \sim 1/r^a defining a {\it bounded} pair force, we show that P(F) converges continuously to a well-defined and rapidly decreasing PDF if and only if the {\it pair force} is absolutely integrable, i.e., for a > d-1, where d is the spatial dimension. We refer to this case as {\it dynamically short-range}, because the dominant contribution to the force on a typical particle in this limit arises from particles in a finite neighborhood around it. For the {\it dynamically long-range} case, i.e., a \leq d-1, on the other hand, the dominant contribution to the force comes from the mean field due to the bulk, which becomes undefined in this limit. We discuss also how, for a \leq d-1 (and notably, for the case of gravity, a=d-2) P(F) may, in some cases, be defined in a weaker sense. This involves a regularization of the force summation which is generalization of the procedure employed to define gravitational forces in an infinite static homogeneous universe. We explain that the relevant classification in this context is, however, that which divides pair forces with a > d-2 (or a < d-2), for which the PDF of the {\it difference in forces} is defined (or not defined) in the infinite system limit, without any regularization. In the former case dynamics can, as for the (marginal) case of gravity, be defined consistently in an infinite uniform system., 12 pages, 1 figure; significantly shortened and focussed, additional references, version to appear in J. Stat. Phys

As part of its response to the global banking crisis and a sharp downturn in domestic economic prospects, the Bank of England’s Monetary Policy Committee (MPC) began a programme of large-scale asset purchases (commonly referred to as quantitative easing or QE) in March 2009, with the aim of injecting additional money into the economy and so increasing nominal spending growth to a rate consistent with meeting the CPI inflation target in the medium term. By February 2010, the MPC had made £200 billion of purchases, most of which had been of UK government securities (gilts). Based on analysis of the reaction of financial market prices and econometric estimates, this paper attempts to assess the impact of the Bank’s QE policy on asset prices. Our estimates of the reaction of gilt prices to the programme suggest that QE may have depressed gilt yields by about 100 basis points. On balance the evidence seems to suggest that the largest part of the impact of QE came through a portfolio rebalancing channel. The wider impact on other asset prices is more difficult to disentangle from other influences: the initial impact was muted but the overall effects were potentially much larger, though subject to considerable uncertainty.

Fluorescent derivatives of phalloidin are widely used to measure filamentous actin (F-actin) levels and to stabilize F-actin. We have characterized the kinetics and affinity of binding of tetramethylrhodaminyl (TRITC)-phalloidin to rabbit skeletal muscle F-actin and to F-actin in lysates of rabbit polymorphonuclear leukocytes (PMNs). We have defined conditions where TRITC-phalloidin can be used to inhibit F-actin depolymerization and to quantify F-actin without prior fixation. By equilibrium measurements, the affinity of TRITC-phalloidin binding to rabbit skeletal muscle F-actin (pyrene labeled) or to PMN lysate F-actin was 1-4 x 10(-7) M. In both cases, the stoichiometry of binding was approximately 1:1. Kinetic measurements of TRITC-phalloidin binding to PMN lysate F-actin resulted in an association rate constant of 420 +/- 120 M-1 sec-1 and a dissociation rate constant of 8.3 +/- 0.9 x 10(-5) sec-1. The affinity calculated from the kinetic measurements (2 +/- 1 x 10(-7) M) agreed well with that obtained by equilibrium measurements. The rate with which 0.6 microM TRITC-phalloidin inhibited 0.1 microM pyrenyl F-actin depolymerization (90% inhibition in 10 sec) was much faster than the rate of binding to pyrenyl F-actin (less than 1% bound in 10 sec), suggesting that phalloidin binds to filament ends more rapidly than to the rest of the filament. We show that TRITC-phalloidin can be used to measure F-actin levels in cell lysates when G-actin is also present (i.e., in cell lysates at high concentrations) if DNase I is included to prevent phalloidin-induced polymerization.

When an open system of classical point particles interacting by Newtonian gravity collapses and relaxes violently, an arbitrary amount of energy may in principle be carried away by particles which escape to infinity. We investigate here, using numerical simulations, how this released energy and other related quantities (notably the binding energy and size of the virialized structure) depends on the initial conditions, for the one parameter family of starting configurations given by randomly distributing N cold particles in a spherical volume. Previous studies have established that the minimal size reached by the system scales approximately as N^{-1/3}, a behaviour which follows trivially when the growth of perturbations (which regularize the singularity of the cold collapse in the infinite N limit) are assumed to be unaffected by the boundaries. Our study shows that the energy ejected grows approximately in proportion to N^{1/3}, while the fraction of the initial mass ejected grows only very slowly with N, approximately logarithmically, in the range of N simulated. We examine in detail the mechanism of this mass and energy ejection, showing explicitly that it arises from the interplay of the growth of perturbations with the finite size of the system. A net lag of particles compared to their uniform spherical collapse trajectories develops first at the boundaries and then propagates into the volume during the collapse. Particles in the outer shells are then ejected as they scatter through the time dependent potential of an already re-expanding central core. Using modified initial configurations we explore the importance of fluctuations at different scales, and discreteness (i.e. non-Vlasov) effects in the dynamics., 20 pages, 27 figures; revised version with small changes and corrections, to appear in MNRAS

This paper describes an architectural concept for a Small Lunar Exploration and Delivery System to operate as a platform for emplacing payloads into lunar orbit and onto the lunar surface, while providing mobility for surface exploration, science, and infrastructure. The concept leverages emerging services that are capable of delivering payloads to Low Earth Orbit (LEO), while utilizing new and old technologies to build a platform for transfer to Low Lunar Orbit (LLO). Advances and miniaturization in avionics, navigation, power, and propulsion systems enable a unique opportunity to develop a system that is both capable of landing on the lunar surface and providing surface mobility with the same system.

Long-horizon interest rates in the major international bond markets fell sharply during 2004 and 2005, at the same time as US policy rates were rising; a phenomenon famously described as a 'conundrum' by Alan Greenspan the Federal Reserve Chairman. But it was arguably the decline in international long real rates over this period which was more unusual and, by the end of 2007, long real rates in the United Kingdom remained at recent historical lows. In this paper, we try to shed light on the recent behaviour of long real rates, by estimating several empirical models of the term structure of real interest rates, derived from UK index-linked bonds. We adopt a standard 'finance' approach to modelling the real term structure, using an essentially affine framework. While being empirically tractable, these models impose the important theoretical restriction of no arbitrage, which enables us to decompose forward real rates into expectations of future short (ie risk-free) real rates and forward real term premia. One general finding that emerges across all the models estimated is that time-varying term premia appear to be extremely important in explaining movements in long real forward rates. Although there is some evidence that long-horizon expected short real rates declined over the conundrum period, our results suggest lower term premia played the dominant role in accounting for the fall in long real rates. This evidence could be consistent with the so-called 'search for yield' and excess liquidity explanations for the conundrum, but it might also partly reflect strong demand for index-linked bonds by institutional investors and foreign central banks.

We study how the two-point density correlation properties of a point particle distribution are modified when each particle is divided, by a stochastic process, into an equal number of identical "daughter" particles. We consider generically that there may be nontrivial correlations in the displacement fields describing the positions of the different daughters of the same "mother" particle and then treat separately the cases in which there are, or are not, correlations also between the displacements of daughters belonging to different mothers. For both cases exact formulas are derived relating the structure factor (power spectrum) of the daughter distribution to that of the mothers. An application of these results is that they give explicit algorithms for generating, starting from regular lattice arrays, stochastic particle distributions with an arbitrarily high degree of large-scale uniformity. Such distributions are of interest, in particular, in the context of studies of self-gravitating systems in cosmology.

Leukapheresis collection of peripheral blood progenitor cells (PBPCs) after granulocyte–colony-stimulating factor (G-CSF; filgrastim) administration has become the preferred method of collecting CD34+ cells for patients with hematologic malignancies receiving high-dose chemotherapy and autologous hematopoietic stem cell transplant (AHSCT). There is no general consensus about adequate number of CD34+ PBPC cell dose needed for successful engraftment after a transplant. In general, 5 million CD34+ cells per kg recipient body weight is considered an adequate cell dose and 2 million CD34+ cell per kg is considered as the minimum acceptable cell dose for an AHSCT.1 The required number of CD34+ stem cells needed for a successful allogeneic stem cell transplant is less well defined.2 In the past 5 years, a handful of studies have reported that infusing higher numbers of allogeneic CD34+ cell per kg is associated with a higher incidence of chronic graft-versus-host disease and higher transplant related mortality.3,4 G-CSF is the most common growth factor used to mobilize patients for PBPC collection.5 When a patient fails to mobilize adequate number of CD34+ cells after G-CSF administration, a combination of two growth factors, usually G-CSF and granulocyte-monocyte–colony-stimulating factor (GM-CSF; sargramostim) or G-CSF and a chemotherapeutic agent, most commonly cyclophosphamide are frequently used. Peripheral CD34+ cell count is performed before collection is begun by apheresis. Most transplant centers in the United States use peripheral CD34+ cell count of 10 per μL as the cutoff to determine when to start collection. Approximately 20 to 30 percent of autologous donors and 10 percent of allogeneic donors fail to mobilize an adequate number of PBPCs for collection. Only about one in four poor mobilizers reaches target CD34+ cell dose despite multiple attempts of remobilization and marrow harvest.6–8 Previous studies have identified several factors that correlate with poor mobilization of PBPCs after G-CSF stimulation. These factors include the effects of prior chemotherapy as well as suppressive effects of the malignant cells on normal hematopoietic progenitors.5 Additional studies have documented the effects of prior chemo-therapy on the ability to harvest sufficient numbers of marrow stem cells or to mobilize CD34+ stem cells for collection by apheresis9,10 Other factors that contribute to poor mobilization include patient age,11 patient diagnosis,12 circulating immature cells,13 immature myeloid cells,14 and white blood cell and mononuclear cell (MNC) counts.15 There is no single established clinical or laboratory test, however, that reliably correlates with marrow reserve and PBPC mobilization. Several studies have shown a significant correlation between the postmobilization, preapheresis peripheral blood CD34+ cell count (pCD34) with PBPC mobilization and yield.15–17 Predicting the ultimate CD34+ cell yield before mobilization treatment would be of great benefit. Potential risks and complications after mobilization treatment, including the risks associated with central line placement and treatment with high-dose G-CSF, will be avoided. Previous studies have demonstrated that stem cell–megakaryocyte–platelet (PLT) lineage is particularly sensitive to damage of marrow microenvironment.18 It was shown that decrease in stem cell numbers after chemo-and radiotherapy exposures directly affect PLT count. In addition, decrease in maturation from altered marrow environment, accessory cells, and growth factor levels affect megakaryocyte maturation, PLT release, and their migration into circulation.19,20 Peripheral CD34+ cell count is only useful in predicting adequate mobilization after growth factor administration. By that time, patients are already exposed to the risks and side effects of the growth factor and clinicians frequently feel compelled to collect despite the low peripheral CD34+ cell count. We therefore attempted to identify other factors that could be used clinically to predict mobilization before growth factor administration. We performed this study to assess if premobilization PLT count is a sensitive predictor of adequate CD34+ cell yield in AHSCT candidates. In addition we determined if PLT count on the day of leukapheresis collection is predictive of CD34+ cell yield for the day. We envision that PLT count would serve as a surrogate marker for hematopoietic stem cell mobilization and would correlate with leukapheresis yield. PLT count, unlike peripheral CD34+ count, is simple to perform, inexpensive, and readily available. We have further assessed the confounding factors that could influence the relationship between the PLT count and the CD34+ cell yield. We developed models that predict adequate CD34+ cell collection. We propose that PLT count in addition to patient clinical profile could be used to identify AHSCT candidates at risk for poor mobilization before initiation of mobilization therapy.

The effects of discreteness arising from the use of the N-body method on the accuracy of simulations of cosmological structure formation are not currently well understood. After a discussion of how the relevant discretisation parameters introduced should be extrapolated to recover the Vlasov-Poisson limit, we study numerically, and with analytical methods we have developed recently, the central issue of how finite particle density affects the precision of results. In particular we focus on the power spectrum at wavenumbers around and above the Nyquist wavenumber, in simulations in which the force resolution is taken smaller than the initial interparticle spacing. Using simulations of identical theoretical initial conditions sampled on four different "pre-initial" configurations (three different Bravais lattices, and a glass) we obtain a {\it lower bound} on the real discreteness error. With the guidance of our analytical results, we establish with confidence that the measured dispersion is not contaminated either by finite box size effects or by subtle numerical effects. Our results show notably that, at wavenumbers {\it below} the Nyquist wavenumber, the dispersion increases monotonically in time throughout the simulation, while the same is true above the Nyquist wavenumber once non-linearity sets in. For normalizations typical of cosmological simulations, we find lower bounds on errors at the Nyquist wavenumber of order of a percent, and larger above this scale. The only way this error may be reduced below these levels at these scales, and indeed convergence to the physical limit firmly established, is by extrapolation, at fixed values of the other relevant parameters, to the regime in which the mean comoving interparticle distance becomes less than the force smoothing scale., Comment: 26 pages, 15 figures, minor changes, slightly shortened, version to be published in MNRAS

We consider the construction of point processes from tilings, with equal volume tiles, of d-dimensional Euclidean space. We show that one can generate, with simple algorithms ascribing one or more points to each tile, point processes which are "superhomogeneous'' (or "hyperuniform''), i.e., for which the structure factor S(k) vanishes when the wavenumber k tends to zero. The exponent of the leading small-k behavior depends in a simple manner on the nature of the correlation properties of the specific tiling and on the conservation of the mass moments of the tiles. Assigning one point to the center of mass of each tile gives the exponent \gamma=4 for any tiling in which the shapes and orientations of the tiles are short-range correlated. Smaller exponents, in the range 4-d 4. Applications to condensed matter physics, and also to cosmology, are briefly discussed., Comment: 13 pages, 2 figures

The usual thermodynamic limit for systems of classical self-gravitating point particles becomes well defined, as a {\it dynamical} problem, using a simple physical prescription for the calculation of the force, equivalent to the so-called ``Jeans' swindle''. The relation of the resulting intrinsically out of equilibrium problem, of particles evolving from prescribed uniform initial conditions in an infinite space, to the one studied in current cosmological models (in an expanding universe) is explained. We then describe results of a numerical study of the dynamical evolution of such a system, starting from a simple class of infinite ``shuffled lattice'' initial conditions. The clustering, which develops in time starting from scales around the grid scale, is qualitatively very similar to that seen in cosmological simulations, which begin from lattices with applied correlated displacements and incorporate an expanding spatial background. From very soon after the formation of the first non-linear structures, a spatio-temporal scaling relation describes well the evolution of the two-point correlations. At larger times the dynamics of these correlations converges to what is termed ``self-similar'' evolution in cosmology, in which the time dependence in the scaling relation is specified entirely by that of the linearized fluid theory. We show how this statistical mechanical ``toy model'' can be useful in addressing various questions about these systems which are relevant in cosmology. Some of these questions are closely analagous to those currently studied in the literature on long range interactions, notably the relation of the evolution of the particle system to that in the Vlasov limit and the nature of approximately quasi-stationary states., 32 pages, 9 figures, chapter of the volume ``Dynamics and Thermodynamics of systems with long range interactions: theory and experiments'', A. Campa, A. Giansanti, G. Morigi, F. Sylos Labini Eds., American Institute of Physics Conference proceedings, 970 (2008). See this URL: http://scitation.aip.org/dbt/dbt.jsp?KEY=APCPCS&Volume=970&Issue=1

We compute a naturally defined measure of the size of the nef cone of a Del Pezzo surface. The resulting number appears in a conjecture of Manin on the asymptotic behavior of the number of rational points of bounded height on the surface. The nef cone volume of a Del Pezzo surface Y with (-2)-curves defined over an algebraically closed field is equal to the nef cone volume of a smooth Del Pezzo surface of the same degree divided by the order of the Weyl group of a simply-laced root system associated to the configuration of (-2)-curves on Y. When Y is defined over a non-closed field of characteristic 0, a similar result holds, except that the associated root system is no longer necessarily simply-laced., v2, 25 pages; major revision containing additional results; comments welcome

N-body simulations sample their initial conditions on an initial particle distribution, which for cosmological simulations is usually a glass or grid, whilst a Poisson distribution is used for galaxy models, spherical collapse etc. These pre-initial conditions have inherent correlations, noise due to discreteness and preferential alignments, whilst the glass distribution is poorly defined and computationally expensive to construct. We present a novel particle distribution which can be useful as a pre-initial condition for N-body simulations, using a simple construction based on a ``quaquaversal'' tiling of space. This distribution has little preferred orientation (i.e. is statistically isotropic), has a rapidly vanishing large scale power-spectrum (P(k) ~ k^4), and is trivial to create. It should be particularly useful for warm dark matter and cold collapse simulations., 8 pages, 6 figures, extended discussion of level of isotropy, matches version accepted in ApJ

We apply a recently developed perturbative formalism which describes the evolution under their self-gravity of particles displaced from a perfect lattice to quantify precisely, up to shell crossing, the effects of discreteness in dissipationless cosmological N-body simulations. We give simple expressions, explicitly dependent on the particle density, for the evolution of power in each mode as a function of red-shift. For typical starting red-shifts the effect of finite particle number is to {\it slow down} slightly the growth of power compared to that in the fluid limit (e.g. by about ten percent at half the Nyquist frequency), and to induce also dispersion in the growth as a function of direction at a comparable level. In the limit that the initial red-shift tends to infinity, at fixed particle density, the evolution in fact diverges from that in the fluid limit (described by the Zeldovich approximation). Contrary to widely held belief, this means that a simulation started at a red-shift much higher than the red-shift of shell crossing actually gives a worse, rather than a better, result. We also study how these effects are modified when there is a small-scale regularization of the gravitational force. We show that such a smoothing may reduce the anisotropy of the discreteness effects, but it then {\it increases} their average effect. This behaviour illustrates the fact that the discreteness effects described here are distinct from those usually considered in this context, due to two-body collisions. Indeed the characteristic time for divergence from the collisionless limit is proportional to $N^{2/3}$, rather than $N/ \log N$ in the latter case., 18 pages, 10 figures, sequel to astro-ph/0410451 (on initial conditions), final version with minor changes, to appear in Phys. Rev. D

We study the evolution under their self-gravity of infinite ``shuffled lattice'' particle distributions, focussing specifically on the comparison of this evolution with that of ``daughter'' particle distributions, defined by a simple coarse-graining procedure. We consider both the case that such coarse-grainings are performed (i) on the initial conditions, and (ii) at a finite time with a specific additional prescription. In numerical simulations we observe that, to a first approximation, these coarse-grainings represent well the evolution of the two-point correlation properties over a significant range of scales. We note, in particular, that the form of the two-point correlation function in the original system, when it is evolving in the asymptotic ``self-similar'' regime, may be reproduced well in a daughter coarse-grained system in which the dynamics are still dominated by two-body (nearest neighbor) interactions. Using analytical results on the early time evolution of these systems, however, we show that small observed differences between the evolved system and its coarse-grainings at the initial time will in fact diverge as the ratio of the coarse-graining scale to the original inter-particle distance increases. The second coarse-graining studied, performed at a finite time in a specified manner, circumvents this problem. It also makes more physically transparent why gravitational dynamics from these initial conditions tends toward a ``self-similar'' evolution. We finally discuss the precise definition of a limit in which a continuum (specifically Vlasov-like) description of the observed linear and non-linear evolution should be applicable., Comment: 21 pages, 8 eps figures, 2 jpeg figures (available in high resolution at http://pil.phys.uniroma1.it/~sylos/PRD_dec_2006/)

In cosmology numerical simulations of structure formation are now of central importance, as they are the sole instrument for providing detailed predictions of current cosmological models for a whole class of important constraining observations. These simulations are essentially molecular dynamics simulations of N (>> 1), now up to of order several billion) particles interacting through their self-gravity. While their aim is to produce the Vlasov limit, which describes the underlying (``cold dark matter'') models, the degree to which they actually do produce this limit is currently understood, at best, only very qualitatively, and there is an acknowledged need for ``a theory of discreteness errors''. In this talk I will describe, for non-cosmologists, both the simulations and the underlying theoretical models, and will then focus on the issue of discreteness, describing some recent progress in addressing this question quantitatively., 8 pages, proceedings (refereed) of "Vlasovia 2006", 2nd int'l workshop on the theory and applications of the Vlasov equation, Florence, September 2006. A more detailed report on recent progress may be found at arXiv:0805.1357

During week 1/2005 (week ending 9 January), influenza activity in Ireland showed a marked increase from previous weeks. However, this was followed by a rapid decline in week 2/2005

We present a perturbative treatment of the evolution under their mutual self-gravity of particles displaced off an infinite perfect lattice, both for a static space and for a homogeneously expanding space as in cosmological N-body simulations. The treatment, analogous to that of perturbations to a crystal in solid state physics, can be seen as a discrete (i.e. particle) generalization of the perturbative solution in the Lagrangian formalism of a self-gravitating fluid. Working to linear order, we show explicitly that this fluid evolution is recovered in the limit that the initial perturbations are restricted to modes of wavelength much larger than the lattice spacing. The full spectrum of eigenvalues of the simple cubic lattice contains both oscillatory modes and unstable modes which grow slightly faster than in the fluid limit. A detailed comparison of our perturbative treatment, at linear order, with full numerical simulations is presented, for two very different classes of initial perturbation spectra. We find that the range of validity is similar to that of the perturbative fluid approximation (i.e. up to close to ``shell-crossing''), but that the accuracy in tracing the evolution is superior. The formalism provides a powerful tool to systematically calculate discreteness effects at early times in cosmological N-body simulations., 25 pages, 21 figures

Among the most challenging patients cared for in critical care medicine are the recipients of hematopoietic stem cell transplantation (HSCT). HSCT is now widely used as a definitive therapy for the treatment of pediatric malignancies and inborn errors of metabolism. Critical care services are required for treatment of complications of HSCT. Formerly thought to have an essentially futile prognosis, outcomes from critical care of HSCT patients have demonstrated steady improvement in many areas during the past two decades. Improvements in the management of respiratory failure, sepsis, and multiple organ system failure have resulted from improvement in oncology and critical care practices. Herein, we review the methods available for outcomes prediction, recent advances in critical care of HSCT patients, and possible directions for future investigation.

When confronted with a radiographic osteolytic lesion where the diagnosis of Paget disease is considered, preservation of fatty marrow signal intensity on MRI excludes more ominous diagnostic considerations.

We discuss some of the basic implications of recent results on galaxy correlations published by the SDSS collaboration. In particular we focus on the evidence which has been recently presented for the scale and nature of the transition to homogeneity in the galaxy distribution, and results which describe the dependence of clustering on luminosity. The two questions are in fact strictly entangled, as the stability of the measure of the amplitude of the correlation function depends on the scale at which the mean density becomes well defined. We note that the recent results which indicate the convergence to well defined homogeneity in a volume equivalent to that of a sphere of radius 70 Mpc/h, place in doubt previous detections of ``luminosity bias'' from measures of the amplitude of the correlation function. We emphasize that the way to resolve these issues is to first use, in volume limited samples corresponding to different ranges of luminosity, the unnormalized two point statistics to establish the scale (and value) at which the mean density becomes well defined. We note also that the recent SDSS results for these statistics are in good agreement with those obtained by us through analyses of many previous samples, confirming in particular that the galaxy distribution is well described by a fractal dimension D ~ 2 up to a scale of at least 20 Mpc/h. We discuss critically the agreement of this new data with current theoretical models., 6 pages, 1 figure. Revised version with minor corrections. To be published in Astronomy and Astrophysics

The relation between the results of cosmological N-body simulations, and the continuum theoretical models they simulate, is currently not understood in a way which allows a quantification of N dependent effects. In this first of a series of papers on this issue, we consider the quantification of such effects in the initial conditions of such simulations. A general formalism developed in [1] allows us to write down an exact expression for the power spectrum of the point distributions generated by the standard algorithm for generating such initial conditions. Expanded perturbatively in the amplitude of the input (i.e. theoretical, continuum) power spectrum, we obtain at linear order the input power spectrum, plus two terms which arise from discreteness and contribute at large wavenumbers. For cosmological type power spectra, one obtains as expected, the input spectrum for wavenumbers k smaller than that characteristic of the discreteness. The comparison of real space correlation properties is more subtle because the discreteness corrections are not as strongly localised in real space. For cosmological type spectra the theoretical mass variance in spheres and two point correlation function are well approximated {\it above} a finite distance. For typical initial amplitudes this distance is a few times the inter-particle distance, but it diverges as this amplitude (or, equivalently, the initial red-shift of the cosmological simulation) goes to zero, at fixed particle density. We discuss briefly the physical significance of these discreteness terms in the initial conditions, in particular with respect to the definition of the continuum limit of N-body simulations., Final published version, 22 pages and 16 figures, very significantly revised, one important correction (range of allowed exponents), modified title (now part one of a series)

A well known argument in cosmology gives that the power spectrum (or structure function) $P(k)$ of mass density fluctuations produced from a uniform initial state by physics which is causal (i.e. moves matter and momentum only up to a finite scale) has the behaviour $P(k) \propto k^4$ at small $k$. Noting the assumption of analyticity at $k=0$ of $P(k)$ in the standard derivation of this result, we introduce a class of solvable one dimensional models which allows us to study the relation between the behaviour of $P(k)$ at small $k$ and the properties of the probability distribution $f(l)$ for the spatial extent $l$ of mass and momentum conserving fluctuations. We find that the $k^4$ behaviour is obtained in the case that the first {\it six} moments of $f(l)$ are finite. Interestingly the condition that the fluctuations be localised - taken to correspond to the convergence of the first two moments of $f(l)$ - imposes only the weaker constraint $P(k) \propto k^n$ with $n$ anywhere in the range $0< n \leq 4$. We interpret this result to suggest that the causality bound will be loosened in this way if quantum fluctuations are permitted., 7 pages, 2 figures; revised version with considerable changes to presentation (including modified title), results and conclusions unchanged; version to appear in Europhys. Lett

In 1999, Lockheed Martin developed an approach called LM21, for Lockheed Martin in the 21st century, to identify best practices for increasing efficiency and improving financial and operating performance, Leaders soon realized that best practice sharing was lust one means to a higher end, The ultimate goal is to create a system that consistently achieves excellence for our customers, shareholders, and employees, We selected and implemented the management philosophies called Lean and Six Sigma, This article describes the Lean Enterprise at Lockheed Martin and the steps taken to make it a reality

There are a large number of labour market indicators that could be used by monetary policy makers to assess the state of the labour market and the associated implications for inflationary pressure. This paper attempts to assess their relative merits by evaluating their past performance in forecasting movements in price and wage inflation. This is done by considering both their ex post performance in predicting inflation - using conventional in-sample Granger causality tests - and their performance ex ante - using simulated out-of-sample forecasting tests over the period 1985-2000, based on both recursive and rolling-window estimation. These criteria lead to rather different conclusions. In sample, most labour market indicators appear to be statistically significant in an inflation-forecasting equation, but out of sample a much smaller number of labour market indicator models are better at forecasting inflation than a simple autoregression, with virtually none outperforming this benchmark over the period since 1995. The labour market indicator models that perform relatively well out of sample tend to be sensitive to the precise choice of inflation measure, sample period and estimation method, though there is some evidence that pooling across individual forecasts produces more reliable results. One apparently robust result, however, is that the unemployment rate gap, the most commonly used measure of labour market tightness, performs poorly in out-of-sample forecasts across a range of specifications.

In this lecture we address three different but related aspects of the initial continuous fluctuation field in standard cosmological models. Firstly we discuss the properties of the so-called Harrison-Zeldovich like spectra. This power spectrum is a fundamental feature of all current standard cosmological models. In a simple classification of all stationary stochastic processes into three categories, we highlight with the name ``super-homogeneous'' the properties of the class to which models like this, with $P(0)=0$, belong. In statistical physics language they are well described as glass-like. Secondly, the initial continuous density field with such small amplitude correlated Gaussian fluctuations must be discretised in order to set up the initial particle distribution used in gravitational N-body simulations. We discuss the main issues related to the effects of discretisation, particularly concerning the effect of particle induced fluctuations on the statistical properties of the initial conditions and on the dynamical evolution of gravitational clustering., Comment: 28 pages, 1 figure, to appear in Proceedings of 9th Course on Astrofundamental Physics, International School D. Chalonge, Kluwer, eds N.G. Sanchez and Y.M. Pariiski, uses crckapb.st pages, 3 figure, ro appear in Proceedings of 9th Course on Astrofundamental Physics, International School D. Chalonge, Kluwer, Eds. N.G. Sanchez and Y.M. Pariiski, uses crckapb.sty

Infection-associated hemophagocytic syndrome is an unusual disease with a high mortality rate. A variety of treatment modalities have been used with limited success. We report three patients with infection-associated hemophagocytic syndrome successfully treated with intravenously administered immune globulin.

In most direct estimates of the mass density (visible or dark) of the Universe, a central input parameter is the luminosity density of the Universe. Here we consider the measurement of this luminosity density from red-shift surveys, as a function of the yet undetermined characteristic scale R_H at which the spatial distribution of visible matter tends to a well defined homogeneity. Making the canonical assumption that the cluster mass to luminosity ratio M/L is the universal one, we can estimate the total mass density as a function \Omega_m(R_H,M/L). Taking the highest estimated cluster value M/L ~300h and a conservative lower limit R_H > 20 Mpc/h, we obtain the upper bound \Omega_m < 0.1 . We note that for values of the homogeneity scale R_H in the range R_H ~ (90 +/- 45) hMpc, the value of \Omega_m may be compatible with the nucleosynthesis inferred density in baryons., Comment: 16 pages, latex, no figures. To be published in Astrophysical Journal Letters

This talk is a status report on our study of quantum transport equations relevant for baryogenesis computations. Our main finding is that, as a consequence of localization in space, the quasiparticle picture of the plasma dynamics breaks down at first non-trivial order in gradient expansion. While in this talk we focus on bosons, we expect that a similar picture holds for fermions. We then argue that the quasiparticle picture is recovered in the adiabatic limit of frequent scattering., 7 pages, 2 figures, macro sprocl.sty, plenary talk given by T. Prokopec at COSMO-99, Trieste, Italy, Sep 27 - Oct 2, 1999

We derive quantum Boltzmann equations from Schwinger-Dyson equations in gradient expansion for a weakly coupled scalar field theory with a spatially varying mass. We find that at higher order in gradients a full description of the system requires specifying not only an on shell distribution function but also a finite number of its derivatives, or equivalently its higher moments. These derivatives describe quantum coherence arising as a consequence of localization in position space. We then show that in the limit of frequent scatterings coherent quantum effects are suppressed, and the transport equations reduce to the single Boltzmann equation for particle density, in which particles flow along modified semiclassical trajectories in phase space., 16 pages, 2 figures, LaTeX with epsf macro

This paper examines the same-day reaction of a variety of UK asset prices to monthly RPI inflation announcements over a sample period extending from the early 1980s until April 1997, the month before the Bank of England was given operational independence for setting interest rates. These announcements are decomposed into their expected and unexpected, or ‘news’, components using survey data on financial analysts' inflation expectations and, as a cross-check, prediction errors from a time-series model of inflation. It is found that markets are efficient, in that asset prices do not respond to the expected component of RPI announcements. Generally, only government bond prices are sensitive to inflation news, and this sensitivity appears particularly marked after late 1992, when the UK adopted an explicit inflation target. The responsiveness of implied medium and long-term forward inflation rates (calculated from conventional and index-linked bonds) during the post-1992 period is consistent with the expected...