74 research outputs found

    Archaeologists and the Archival Record

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    Archaeologists study the material record, bits of things that have been either intentionally or unintentionally modified by human beings to become artifacts. In a word, stuff. Practitioners are expected to become familiar with a vast range of stuff and the characteristics thereof: from the flowing ripple marks left on a fragment of stone after it has been hammered off of a larger piece to produce a flake, to the peculiar, stretched cross-section that indicates a square nail has been machine-cut rather than hand-forged. One particularly important subset of stuff is the archival record which, besides consisting itself of artifacts of paper and ink, conveys a great deal of information relating to much of the rest of the stuff in the world

    Power spectrum for the small-scale Universe

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    The first objects to arise in a cold dark matter universe present a daunting challenge for models of structure formation. In the ultra small-scale limit, CDM structures form nearly simultaneously across a wide range of scales. Hierarchical clustering no longer provides a guiding principle for theoretical analyses and the computation time required to carry out credible simulations becomes prohibitively high. To gain insight into this problem, we perform high-resolution (N=720^3 - 1584^3) simulations of an Einstein-de Sitter cosmology where the initial power spectrum is P(k) propto k^n, with -2.5 < n < -1. Self-similar scaling is established for n=-1 and n=-2 more convincingly than in previous, lower-resolution simulations and for the first time, self-similar scaling is established for an n=-2.25 simulation. However, finite box-size effects induce departures from self-similar scaling in our n=-2.5 simulation. We compare our results with the predictions for the power spectrum from (one-loop) perturbation theory and demonstrate that the renormalization group approach suggested by McDonald improves perturbation theory's ability to predict the power spectrum in the quasilinear regime. In the nonlinear regime, our power spectra differ significantly from the widely used fitting formulae of Peacock & Dodds and Smith et al. and a new fitting formula is presented. Implications of our results for the stable clustering hypothesis vs. halo model debate are discussed. Our power spectra are inconsistent with predictions of the stable clustering hypothesis in the high-k limit and lend credence to the halo model. Nevertheless, the fitting formula advocated in this paper is purely empirical and not derived from a specific formulation of the halo model.Comment: 30 pages including 10 figures; accepted for publication in MNRA

    Lensing-Induced Structure of Submillimeter Sources: Implications for the Microwave Background

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    We consider the effect of lensing by galaxy clusters on the angular distribution of submillimeter wavelength objects. While lensing does not change the total flux and number counts of submillimeter sources, it can affect the number counts and fluxes of flux-limited samples. Therefore imposing a flux cut on point sources not only reduces the overall Poisson noise, but imprints the correlations between lensing clusters on the unresolved flux distribution. Using a simple model, we quantify the lensing anisotropy induced in flux-limited samples and compare this to Poisson noise. We find that while the level of induced anisotropies on the scale of the cluster angular correlation length is comparable to Poisson noise for a slowly evolving cluster model, it is negligible for more realistic models of cluster evolution. Thus the removal of point sources is not expected to induce measurable structure in the microwave or far-infrared backgrounds.Comment: 22 pages, 9 figures, accepted to Astrophysical Journa

    The prevalence of non-fatal overdose among people who inject drugs:a multi-stage systematic review and meta-analysis

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    People who inject drugs (PWID) are at an elevated risk of fatal overdose in the first year after experiencing a non-fatal event. Such non-fatal events may also result in overdose-related sequelae, ranging from physical injury to paralysis. Given variation in drug markets and treatment availability across countries and regions, we may see similar variations in non-fatal overdose prevalence. Monitoring non-fatal overdose prevalence among PWID is essential for informing treatment intervention efforts, and thus our review aims to estimate the global, regional, and national prevalence of non-fatal overdose, and determine characteristics associated with experiencing such an event.We conducted a systematic review and meta-analyses to estimate country, regional, and global estimates of recent and lifetime non-fatal overdose prevalence among PWID. Using meta-regression analyses we also determined associations between sample characteristics and non-fatal overdose prevalence.An estimated 3.2 (1.8-5.2) million PWID have experienced at least one overdose in the previous year. Among PWID, 20.5% (15.0-26.1%) and 41.5% (34.6-48.4%) had experienced a non-fatal event in the previous 12 months and lifetime respectively. Frequent injecting was strongly associated with PWID reporting recent and lifetime non-fatal overdose. Estimates of recent non-fatal overdose were particularly high in Asia and North America.Around one in five PWID are at an elevated risk of fatally overdosing every year, however there is substantial geographical variation. In countries with higher rates of non-fatal overdose there is need to introduce or mainstream overdose prevention strategies such as opioid agonist treatment and naloxone administration training programs

    Global systematic review and ecological analysis of HIV in people who inject drugs:National population sizes and factors associated with HIV prevalence

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    Background People who inject drugs (PWID) are at elevated risk of HIV infection. Data on population sizes of PWID living with HIV are needed to inform the implementation of prevention, treatment and care programs. We estimated national population sizes of people who recently (past 12 months) injected drugs living with HIV and evaluated ecological associations with HIV prevalence in PWID. Methods We used national data on the prevalence of injecting drug use and of HIV among PWID, derived from systematic reviews, to estimate national population sizes of PWID living with HIV. Uncertainty was estimated using Monte Carlo simulation with 100,000 draws. We extracted data on sample characteristics from studies of HIV prevalence among PWID, and identified national indicators that have been observed or hypothesised to be associated with HIV prevalence in PWID. We used linear regression to evaluate associations between these variables and HIV prevalence in PWID. Results Four countries comprised 55% of the estimated global population of PWID living with HIV: Russia (572,500; 95% uncertainty interval (UI) 235,500–1,036,500); Brazil (462,000; 95% UI 283,500–674,500); China (316,500; 95% UI 171,500–493,500), and the United States (195,500; 95% UI 80,000–343,000). Greater anti-HCV prevalence and national income inequality were associated with greater HIV prevalence in PWID. Conclusion The countries with the largest populations of PWID living with HIV will need to dramatically scale up prevention, treatment and care interventions to prevent further increases in population size. The association between anti-HCV prevalence and HIV prevalence among PWID corroborates findings that settings with increasing HCV should implement effective interventions to prevent HIV outbreaks. The association between income inequality and HIV among PWID reinforces the need to implement structural interventions alongside targeted individual-level strategies

    Different paths to the modern state in Europe: the interaction between domestic political economy and interstate competition

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    Theoretical work on state formation and capacity has focused mostly on early modern Europe and on the experience of western European states during this period. While a number of European states monopolized domestic tax collection and achieved gains in state capacity during the early modern era, for others revenues stagnated or even declined, and these variations motivated alternative hypotheses for determinants of fiscal and state capacity. In this study we test the basic hypotheses in the existing literature making use of the large date set we have compiled for all of the leading states across the continent. We find strong empirical support for two prevailing threads in the literature, arguing respectively that interstate wars and changes in economic structure towards an urbanized economy had positive fiscal impact. Regarding the main point of contention in the theoretical literature, whether it was representative or authoritarian political regimes that facilitated the gains in fiscal capacity, we do not find conclusive evidence that one performed better than the other. Instead, the empirical evidence we have gathered lends supports to the hypothesis that when under pressure of war, the fiscal performance of representative regimes was better in the more urbanized-commercial economies and the fiscal performance of authoritarian regimes was better in rural-agrarian economie

    Self-Renewal of Acute Lymphocytic Leukemia Cells Is Limited by the Hedgehog Pathway Inhibitors Cyclopamine and IPI-926

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    Conserved embryonic signaling pathways such as Hedgehog (Hh), Wingless and Notch have been implicated in the pathogenesis of several malignancies. Recent data suggests that Hh signaling plays a role in normal B-cell development, and we hypothesized that Hh signaling may be important in precursor B-cell acute lymphocytic leukemia (B-ALL). We found that the expression of Hh pathway components was common in human B-ALL cell lines and clinical samples. Moreover, pathway activity could be modulated by Hh ligand or several pathway inhibitors including cyclopamine and the novel SMOOTHENED (SMO) inhibitor IPI-926. The inhibition of pathway activity primarily impacted highly clonogenic B-ALL cells expressing aldehyde dehydrogenase (ALDH) by limiting their self-renewal potential both in vitro and in vivo. These data demonstrate that Hh pathway activation is common in B-ALL and represents a novel therapeutic target regulating self-renewal and persistence of the malignant clone
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