1,312 research outputs found
Statistically robust representation and comparison of mortality profiles in archaeozoology
Archaeozoological mortality profiles have been used to infer site-specific subsistence strategies. There is however no common agreement on the best way to present these profiles and confidence intervals around age class proportions. In order to deal with these issues, we propose the use of the Dirichlet distribution and present a new approach to perform age-at-death multivariate graphical comparisons. We demonstrate the efficiency of this approach using domestic sheep/goat dental remains from 10 Cardial sites (Early Neolithic) located in South France and the Iberian Peninsula. We show that the Dirichlet distribution in age-at-death analysis can be used: (i) to generate Bayesian credible intervals around each age class of a mortality profile, even when not all age classes are observed; and (ii) to create 95% kernel density contours around each age-at-death frequency distribution when multiple sites are compared using correspondence analysis. The statistical procedure we present is applicable to the analysis of any categorical count data and particularly well-suited to archaeological data (e.g. potsherds, arrow heads) where sample sizes are typically small
Did long-memory of liquidity signal the European sovereign debt crisis?
This paper analyses high frequency MTS data to comprehensively evaluate the liquidity of the European sovereign bond markets before and during the European sovereign debt crisis for eleven countries. The Hill index, Generalized Hurst exponent and Dynamic Conditional Score are employed to evaluate the properties of the bid-ask spread. Sovereign bonds exhibit the stylized facts reported for a range of financial markets. The 1-min interval analysis indicates the level of bid-ask spread exhibits long-memory and the change in bid-ask spread experiences volatility clustering. In a dynamic setting, the volatility of bid-ask spread also exhibits long-memory in most European sovereign bond markets across all three maturities. Long-memory effects diminish (disappear) for 5-min (15-min) interval, and for short-term maturity (peripheral countries) is stronger than long-term maturity (core countries). Analysis of sub-periods indicates that long-memory process reached its peak during European sovereign debt crisis from May 2010 to December 2011. This analysis suggests that estimating long-memory parameters for high-frequency data could be a useful tool to monitor market stability
The determinants of IPO withdrawal – Evidence from Europe
Why do companies not follow through with an IPO after filing for one? This question is investigated by examining common stock IPOs for the largest countries in Europe. We cover 80% of the Western European IPO market over the 2001–2015 period. We establish that the IPO phenomenon of withdrawal is a common feature of equity markets and identify key characteristics that influence the probability of withdrawal. Findings indicate that venture capital or private equity involvement, the presence of negative news, CEO duality, or the intent to retire debt increase the probability of IPO withdrawal. On the other hand, higher levels of corporate governance or trading volume decrease the pssrobability of IPO withdrawal. We argue that imminent agency conflicts and the lack of appropriate control mechanisms can force a company to withdraw from the IPO
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Dissecting the illegal ivory trade: an analysis of ivory seizures data
Reliable evidence of trends in the illegal ivory trade is important for informing decision making for elephants but it is difficult to obtain due to the covert nature of the trade. The Elephant Trade Information System, a global database of reported seizures of illegal ivory, holds the only extensive information on illicit trade available. However inherent biases in seizure data make it difficult to infer trends; countries differ in their ability to make and report seizures and these differences cannot be directly measured. We developed a new modelling framework to provide quantitative evidence on trends in the illegal ivory trade from seizures data. The framework used Bayesian hierarchical latent variable models to reduce bias in seizures data by identifying proxy variables that describe the variability in seizure and reporting rates between countries and over time. Models produced bias-adjusted smoothed estimates of relative trends in illegal ivory activity for raw and worked ivory in three weight classes. Activity is represented by two indicators describing the number of illegal ivory transactions--Transactions Index--and the total weight of illegal ivory transactions--Weights Index--at global, regional or national levels. Globally, activity was found to be rapidly increasing and at its highest level for 16 years, more than doubling from 2007 to 2011 and tripling from 1998 to 2011. Over 70% of the Transactions Index is from shipments of worked ivory weighing less than 10 kg and the rapid increase since 2007 is mainly due to increased consumption in China. Over 70% of the Weights Index is from shipments of raw ivory weighing at least 100 kg mainly moving from Central and East Africa to Southeast and East Asia. The results tie together recent findings on trends in poaching rates, declining populations and consumption and provide detailed evidence to inform international decision making on elephants
Dynamically Driven Evolution of the Interstellar Medium in M51
We report the highest-fidelity observations of the spiral galaxy M51 in CO
emission, revealing the evolution of giant molecular clouds (GMCs) vis-a-vis
the large-scale galactic structure and dynamics. The most massive GMCs
(so-called GMAs) are first assembled and then broken up as the gas flow through
the spiral arms. The GMAs and their H2 molecules are not fully dissociated into
atomic gas as predicted in stellar feedback scenarios, but are fragmented into
smaller GMCs upon leaving the spiral arms. The remnants of GMAs are detected as
the chains of GMCs that emerge from the spiral arms into interarm regions. The
kinematic shear within the spiral arms is sufficient to unbind the GMAs against
self-gravity. We conclude that the evolution of GMCs is driven by large-scale
galactic dynamics --their coagulation into GMAs is due to spiral arm streaming
motions upon entering the arms, followed by fragmentation due to shear as they
leave the arms on the downstream side. In M51, the majority of the gas remains
molecular from arm entry through the inter-arm region and into the next spiral
arm passage.Comment: 6 pages, including 3 figures. Accepted, ApJ
Anterolateral ligament reconstruction does not delay functional recovery, rehabilitation, and return to sport after anterior cruciate ligament reconstruction. A matched-pair analysis from the SANTI (Scientific ACL Network International) Study Group
Purpose: To determine whether the addition of an anterolateral ligament reconstruction (ALLR) resulted in delayed functional recovery (based on the Knee Santy Athletic Return to Sport [K-STARTS] score) at 6 months after anterior cruciate ligament reconstruction (ACLR). Methods: A retrospective analysis of prospectively collected data from consecutive pa- tients who underwent an ACLR between September 2017 and December 2020 was conducted. Patients who received an isolated hamstring autograft (isolated ACLR group) were propensity matched in a 1:1 ratio to patients who received a hamstring autograft ACLR combined with an ALLR (ACLR-ALLR group). Outcome measures included the Tegner Activity Scale and the K-STARTS testda validated composite return-to-sports test (including the Anterior Cruciate LigamenteReturn to Sport After Injury scale, Qualitative Assessment of Single-Leg Landing tool, limb symmetry index, and ability to change direction using the Modified Illinois Change of Direction Test). Results: The study included 111 matched pairs. At 6 months postoperatively, there were no significant differences between groups in the overall K-STARTS score (65.4 for isolated ACLR vs 61.2 for ACLR-ALLR, P 1⁄4 .087) or the Tegner Activity Scale score (3.7 for isolated ACLR vs 3.8 for ACLR-ALLR, P 1⁄4 .45). In addition, an evaluation of the subscales of the K-STARTS score revealed no disadvantage across the domains of neuromuscular control, limb symmetry index, agility, or psychological readiness to return to sport when an ALLR was performed. Conclusions: The addition of ALLR at the time of ACLR does not delay functional recovery. Spe- cifically, at 6 months postoperatively, there was no disadvantage in patients undergoing ALLR-ACLR, when compared with those undergoing isolated ACLR, with respect to neuromuscular control, limb symmetry indices (hop tests), agility, or psychological readiness to return to sport
Protein crystals in adenovirus type 5-infected cells: requirements for intranuclear crystallogenesis, structural and functional analysis
Intranuclear crystalline inclusions have been observed in the nucleus of epithelial cells infected with Adenovirus serotype 5 (Ad5) at late steps of the virus life cycle. Using immuno-electron microscopy and confocal microscopy of cells infected with various Ad5 recombinants modified in their penton base or fiber domains, we found that these inclusions represented crystals of penton capsomers, the heteromeric capsid protein formed of penton base and fiber subunits. The occurrence of protein crystals within the nucleus of infected cells required the integrity of the fiber knob and part of the shaft domain. In the knob domain, the region overlapping residues 489–492 in the FG loop was found to be essential for crystal formation. In the shaft, a large deletion of repeats 4 to 16 had no detrimental effect on crystal inclusions, whereas deletion of repeats 8 to 21 abolished crystal formation without altering the level of fiber protein expression. This suggested a crucial role of the five penultimate repeats in the crystallisation process. Chimeric pentons made of Ad5 penton base and fiber domains from different serotypes were analyzed with respect to crystal formation. No crystal was found when fiber consisted of shaft (S) from Ad5 and knob (K) from Ad3 (heterotypic S5-K3 fiber), but occurred with homotypic S3K3 fiber. However, less regular crystals were observed with homotypic S35-K35 fiber. TB5, a monoclonal antibody directed against the Ad5 fiber knob was found by immunofluorescence microscopy to react with high efficiency with the intranuclear protein crystals in situ. Data obtained with Ad fiber mutants indicated that the absence of crystalline inclusions correlated with a lower infectivity and/or lower yields of virus progeny, suggesting that the protein crystals might be involved in virion assembly. Thus, we propose that TB5 staining of Ad-infected 293 cells can be used as a prognostic assay for the viability and productivity of fiber-modified Ad5 vectors
A Warp in Progress : H I and Radio Continuum Observations of the Spiral NGC 3145
Date of Acceptance: 16/06/2015We present VLA H I and 6 cm radio continuum observations of the spiral NGC 3145 and H I observations of its two companions, NGC 3143 and PGC 029578. In optical images NGC 3145 has stellar arms that appear to cross, forming "X"-features. Our radio continuum observations rule out shock fronts at 3 of the 4 "X"-features. In the middle-to-outer disk, the H I line-profiles of NGC 3145 are skewed. Relative to the disk, the gas in the skewed wing of the line-profiles has z-motions away from us on the approaching side of the galaxy and z-motions of about the same magnitude (about 40 km/s) towards us on the receding side. These warping motions imply that there has been a perturbation with a sizeable component perpendicular to the disk over large spatial scales. Two features in NGC 3145 have velocities indicating that they are out-of-plane tidal arms. One is an apparent branch of a main spiral arm; the velocity of the branch is 150 km/s greater than the spiral arm where they appear to intersect in projection. The other is an arm that forms 3 of the "X"-features. It differs in velocity by 56 km/s from the disk at the same projected location. Based on its SFR and H I properties, NGC 3143 is the more likely of the two companions to have interacted with NGC 3145 recently. A simple analytic model demonstrates that an encounter between NGC 3143 and NGC 3145 is a plausible explanation for the observed warping motions in NGC 3145.Peer reviewe
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