4,429 research outputs found
Predicting and Discovering True Muonium
The recent observation of discrepancies in the muonic sector motivates
searches for the yet undiscovered atom true muonium . To leverage
potential experimental signals, precise theoretical calculations are required.
I will present the on-going work to compute higher-order corrections to the
hyperfine splitting and the Lamb shift. Further, possible detection in rare
meson decay experiments like REDTOP and using true muonium production to
constrain mesonic form factors will be discussed.Comment: 4 pages. Talk presented at EXA2017 in Vienna, Austri
Data and Predictive Analytics Use for Logistics and Supply Chain Management
Purpose
The purpose of this paper is to explore the social process of Big Data and predictive analytics (BDPA) use for logistics and supply chain management (LSCM), focusing on interactions among technology, human behavior and organizational context that occur at the technology’s post-adoption phases in retail supply chain (RSC) organizations. Design/methodology/approach
The authors follow a grounded theory approach for theory building based on interviews with senior managers of 15 organizations positioned across multiple echelons in the RSC. Findings
Findings reveal how user involvement shapes BDPA to fit organizational structures and how changes made to the technology retroactively affect its design and institutional properties. Findings also reveal previously unreported aspects of BDPA use for LSCM. These include the presence of temporal and spatial discontinuities in the technology use across RSC organizations. Practical implications
This study unveils that it is impossible to design a BDPA technology ready for immediate use. The emergent process framework shows that institutional and social factors require BDPA use specific to the organization, as the technology comes to reflect the properties of the organization and the wider social environment for which its designers originally intended. BDPA is, thus, not easily transferrable among collaborating RSC organizations and requires managerial attention to the institutional context within which its usage takes place. Originality/value
The literature describes why organizations will use BDPA but fails to provide adequate insight into how BDPA use occurs. The authors address the “how” and bring a social perspective into a technology-centric area
Steady state risetimes of shock waves in the atmosphere
A square wave shape is used in the Pestorius algorithm to calculate the risetime of a step shock in the atmosphere. These results agree closely with steady shock calculations. The healing distance of perturbed shocks due to finite wave effects is then investigated for quasi-steady shocks. Perturbed 100 Pa shocks require on the order of 1.0 km travel distance to return to within 10 percent of their steady shock risetime. For 30 Pa shocks, the minimum recovery distance increases to 3.0 km. It is unlikely that finite wave effects can remove the longer risetimes and irregular features introduced into the sonic boom by turbulent scattering in the planetary boundary layer
A comparative evaluation of the efficacy between skeletal traction and skin traction in pre-operative management of femur shaft fractures in Korle Bu Teaching Hospital
Objectives: This study is to compare the outcomes of pre-operative skeletal and skin traction in adult femoral shaft fractures awaiting surgical fixation within two weeks of presentation to the Accident Center of Korle Bu Teaching Hospital.Methods: This study was a clinical trial on 86 recruited patients with closed femoral shaft fractures sustained within 24 hours of presentation grouped into 2 groups. Descriptive and inferential statistics comprising frequency, percentage, Chi-square, independent sample t-test and Mann-Whitney U test were used in analysing the data.Results: Of the total number of patients involved in the study, 74% (n=64) were males and 26% (n=22) were females with a mean age of 39.49 (SD ±15). There was no statistically significant difference in the mean visual analogue scale (VAS) pain assessment between the Skin traction group and Trans-tibia skeletal traction group after traction. With regards to complications, the difference between the Skin traction group and the Skeletal traction group was statistically significant (P=0.001). Moreover, the mean blood loss compared with the open type of reduction in the Transtibia skeletal traction group was significantly less than the Skin traction group (p=0.000).Conclusion: This study has shown that both Skeletal traction and Skin traction were equally effective in controlling pre-operative pain in adult patients with femoral shaft fractures and does not affect intra-operative blood loss and postoperative management. Therefore, pre-operative Skin traction can be considered a useful and cost-effective method of maintaining alignment and pain relief in adult femoral shaft fractures.Keywords: Skin traction, Trans-tibia skeletal, reamed Intramedullary nailing, Intra-operative blood loss, Visual Analogue ScaleFunding: Personal Fundin
Pseudorandom Strings from Pseudorandom Quantum States
A fundamental result in classical cryptography is that pseudorandom
generators are equivalent to one-way functions and in fact implied by nearly
every classical cryptographic primitive requiring computational assumptions. In
this work, we consider a variant of pseudorandom generators called quantum
pseudorandom generators (QPRGs), which are quantum algorithms that
(pseudo)deterministically map short random seeds to long pseudorandom strings.
We provide evidence that QPRGs can be as useful as PRGs by providing
cryptographic applications of QPRGs such as commitments and encryption schemes.
Our main result is showing that QPRGs can be constructed assuming the
existence of logarithmic-length quantum pseudorandom states. This raises the
possibility of basing QPRGs on assumptions weaker than one-way functions. We
also consider quantum pseudorandom functions (QPRFs) and show that QPRFs can be
based on the existence of logarithmic-length pseudorandom function-like states.
Our primary technical contribution is a method for pseudodeterministically
extracting uniformly random strings from Haar-random states.Comment: 45 pages, 1 figur
Substrate Induced Structural and Dynamics Changes in Human Phosphomevalonate Iinase and Implications for Mechanism
Phosphomevalonate kinase (PMK) catalyzes an essential step in the mevalonate pathway, which is the only pathway for synthesis of isoprenoids and steroids in humans. PMK catalyzes transfer of the γ-phosphate of ATP to mevalonate 5-phosphate (M5P) to form mevalonate 5-diphosphate. Bringing these phosphate groups in proximity to react is especially challenging, given the high negative charge density on the four phosphate groups in the active site. As such, conformational and dynamics changes needed to form the Michaelis complex are of mechanistic interest. Herein, we report the characterization of substrate induced changes (Mg-ADP, M5P, and the ternary complex) in PMK using NMR-based dynamics and chemical shift perturbation measurements. Mg-ADP and M5P Kd\u27s were 6–60 μM in all complexes, consistent with there being little binding synergy. Binding of M5P causes the PMK structure to compress (τc = 13.5 nsec), whereas subsequent binding of Mg-ADP opens the structure up (τc = 15.6 nsec). The overall complex seems to stay very rigid on the psec-nsec timescale with an average NMR order parameter of S2 ∼0.88. Data are consistent with addition of M5P causing movement around a hinge region to permit domain closure, which would bring the M5P domain close to ATP to permit catalysis. Dynamics data identify potential hinge residues as H55 and R93, based on their low order parameters and their location in extended regions that connect the M5P and ATP domains in the PMK homology model. Likewise, D163 may be a hinge residue for the lid region that is homologous to the adenylate kinase lid, covering the “Walker-A” catalytic loop. Binding of ATP or ADP appears to cause similar conformational changes; however, these observations do not indicate an obvious role for γ-phosphate binding interactions. Indeed, the role of γ-phosphate interactions may be more subtle than suggested by ATP/ADP comparisons, because the conservative O to NH substitution in the β-γ bridge of ATP causes a dramatic decrease in affinity and induces few chemical shift perturbations. In terms of positioning of catalytic residues, binding of M5P induces a rigidification of Gly21 (adjacent to the catalytically important Lys22), although exchange broadening in the ternary complex suggests some motion on a slower timescale does still occur. Finally, the first nine residues of the N-terminus are highly disordered, suggesting that they may be part of a cleavable signal or regulatory peptide sequence. Proteins 2009. © 2008 Wiley-Liss, Inc
Numerical simulation of heat and mass transport during space crystal growth with MEPHISTO
The MEPHISTO space experiments are collaborative United States and French investigations aimed at understanding the fundamentals of crystal growth. Microgravity experiments were conducted aboard the USMP-1 and -2 missions on STS-52 and 62 in October 1992 and March 1994 respectively. MEPHISTO is a French designed and built Bridgman type furnace which uses the Seebeck technique to monitor the solid/liquid interface temperature and Peltier pulsing to mark the location and shape of the solid/liquid interface. In this paper the Bridgman growth of Sn-Bi and Bi-Sn under terrestrial and microgravity conditions is modeled using the finite element code, FIDAP*. The numerical model considers fully coupled heat and mass transport, fluid motion and solid/liquid phase changes in the crystal growth process. The primary goals of this work are: to provide a quantitative study of the thermal buoyancy-induced convection in the melt for the two flight experiments; to compare the vertical and horizontal growth configurations and systematically evaluate the effects of various gravity levels on the solute segregation. Numerical results of the vertical and horizontal Bridgman growth configurations are presented
Mobile Internet Quality Estimation using Self-Tuning Kernel Regression
Modeling and estimation for spatial data are ubiquitous in real life,
frequently appearing in weather forecasting, pollution detection, and
agriculture. Spatial data analysis often involves processing datasets of
enormous scale. In this work, we focus on large-scale internet-quality open
datasets from Ookla. We look into estimating mobile (cellular) internet quality
at the scale of a state in the United States. In particular, we aim to conduct
estimation based on highly {\it imbalanced} data: Most of the samples are
concentrated in limited areas, while very few are available in the rest, posing
significant challenges to modeling efforts. We propose a new adaptive kernel
regression approach that employs self-tuning kernels to alleviate the adverse
effects of data imbalance in this problem. Through comparative experimentation
on two distinct mobile network measurement datasets, we demonstrate that the
proposed self-tuning kernel regression method produces more accurate
predictions, with the potential to be applied in other applications
Factors affecting early re-displacement of paediatric diaphyseal forearm fractures at Korle Bu Teaching Hospital
Background: Complete fractures of the forearm have the potential to displace and angulate with overriding fracture fragments. Maintaining acceptable reduction is not always possible, and re- displacement or re-angulation is the most commonly reported complication. Factors responsible for the re-displacement after an initial acceptable reduction have not been clearly defined. The study aimed to determine the factors that influence early re-displacement of paediatric diaphyseal forearm fractures in Korle-Bu Teaching Hospital.Methods: A prospective study in a cohort of 72 children below the age of 12 years with diaphyseal forearm fracture attending the Orthopaedic clinic were followed with close reduction casting from April 2017-December, 2017. Factors analysed included demographics, initial fracture features and the radiographic indices of the cast quality.Results: 93.1% (67) of the fractures were because of the children falling on an outstretched arm. Majority of the children had a fracture of the distal 1/3 of the radius (n=38, 52.6%). The overall C.I was 0.8 (SD 0.1). The only significant predictor for predicting re-displacement was children falling on an outstretched hand (p-value=0.0).Conclusion: This study has shown that the degree of initial displacement and the ability to achieve good reduction with a well moulded cast, constitute the major factors for early re-displacement of paediatric forearm fracturesKeywords: cast index, intermedullary nailing, elastic stable intramedullary nail, open reduction, internal fixationFunding: Personal fundin
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