Stable salts of the hexacarbonyl chromium(I) cation and its pentacarbonyl-nitrosyl chromium(I) analogue

Homoleptic carbonyl radical cations are a textbook family of complexes hitherto unknown in the condensed phase, leaving their properties and applications fundamentally unexplored. Here we report on two stable 17-electron [Cr(CO)6]•+ salts that were synthesized by oxidation of Cr(CO)6 with [NO]+[Al(ORF)4]− (RF = C(CF3)3)) in CH2Cl2 and with removal of NO gas. Longer reaction times led to NO/CO ligand exchange and formation of the thermodynamically more stable 18-electron species [Cr(CO)5(NO)]+, which belongs to the family of heteroleptic chromium carbonyl/nitrosyl cations. All salts were fully characterized (IR, Raman, EPR, NMR, scXRD, pXRD, magnetics) and are stable at room temperature under inert conditions over months. The facile synthesis of these species enables the thorough investigation of their properties and applications to a broad scientific community

Power of earthquake cluster detection tests

Testing the global earthquake catalogue for indications of non-Poissonian attributes has been an area of intense research, especially since the 2011 Tohoku earthquake. The usual approach is to test statistically for the hypothesis that the global earthquake catalogue is well explained by a Poissonian process. In this paper we analyse one aspect of this problem which has been disregarded by the literature: the power of such tests to detect non-Poissonian features if they existed; that is, the probability of type II statistical errors. We argue that the low frequency of large events and the brevity of our earthquake catalogues reduces the power of the statistical tests so that an unequivocal answer for this question is not granted. We do this by providing a counter example of a stochastic process that is clustered by construction and by analysing the resulting distribution of p-values given by the current tests.Comment: 14 pages, 5 Figure

COMPUTE N-WAY DE-DUPLICATED REACH USING PRIVACY SAFE VECTOR OF COUNTS

Systems and methods for determining the union of the set of user identifiers across multiple publishers are described. Each publisher computing device can use a list of hash functions to hash the respective set of de-duplicated user identifiers. Each publisher can assemble a vector of counts using the respective hashed set of user identifiers, where each coordinate in the vector of counts corresponds to a select of bit positions from the hashed set of user identifiers. Each publisher can add noise to each of the vector of counts to enhance the privacy of the system. Each publisher can transmit the respective vector of counts to a server to compute the union of the multiset without exposing any private or protected information about the user identifiers to any third-party. The server can compute the union of the sets described by the vectors of counts from each of the publishers using at least one of the methods described herein

Detecting sub-MeV neutrons in solid plastic scintillator with gamma-ray discrimination

We report on recent efforts to design a solid plastic scintillation hodoscope to measure neutron production cross sections at low energies. Our program includes not only the development of the detector itself, but also a set of auxiliary measurements which will help characterize its low-energy response. A novel scintillation counter has been developed to detect sub-MeV neutrons while rejecting gamma-ray backgrounds with good efficiency. The detector uses multiple layers of thin solid scintillator, with optical isolation between the adjacent layers. Incident low-energy neutrons produce ionizing recoil particles which remain within just one of the scintillator layers, while background gamma rays create electrons which most often cross the boundary between layers. By observing the trigger pattern within the layers, most gamma-ray backgrounds can be distinguished from the low-energy neutrons of interest. We report on the results of our Monte Carlo studies of this design, as well as on the operation of a prototype detector unit. We also have undertaken a new measurement of the neutron-proton total cross section below 1 MeV. Calculations of the efficiency for detecting low energy neutrons in plastic scintillator rely on accurate low energy n-p cross sections, yet surprisingly few such data currently exist. New measurements which span the region from 150 to 800 keV neutron (lab) energy are reported and discussed. Additionally, we have measured the light response of BC 418 scintillator for recoil proton energies as low as 100 keV. Recoil protons are produced at a known energy in the scintillator by placing it in a neutron beam and detecting in coincidence the elastically scattered neutrons at fixed angle. Our new results extend the energy range of previous measurements of the light response of solid organic scintillators, and may indicate a significantly modified response at the lowest observed energies.United States. Dept. of Energy (Grant No. DE-FG52-10NA29651

Are megaquakes clustered?

We study statistical properties of the number of large earthquakes over the past century. We analyze the cumulative distribution of the number of earthquakes with magnitude larger than threshold M in time interval T, and quantify the statistical significance of these results by simulating a large number of synthetic random catalogs. We find that in general, the earthquake record cannot be distinguished from a process that is random in time. This conclusion holds whether aftershocks are removed or not, except at magnitudes below M = 7.3. At long time intervals (T = 2-5 years), we find that statistically significant clustering is present in the catalog for lower magnitude thresholds (M = 7-7.2). However, this clustering is due to a large number of earthquakes on record in the early part of the 20th century, when magnitudes are less certain.Comment: 5 pages, 5 figure

Mathematical Model Creation for Cancer Chemo-Immunotherapy

One of the most challenging tasks in constructing a mathematical model of cancer treatment is the calculation of biological parameters from empirical data. This task becomes increasingly difficult if a model involves several cell populations and treatment modalities. A sophisticated model constructed by de Pillis et al., Mixed immunotherapy and chemotherapy of tumours: Modelling, applications and biological interpretations, J. Theor. Biol. 238 (2006), pp. 841–862; involves tumour cells, specific and non-specific immune cells (natural killer (NK) cells, CD8 T cells and other lymphocytes) and employs chemotherapy and two types of immunotherapy (IL-2 supplementation and CD8 T-cell infusion) as treatment modalities. Despite the overall success of the aforementioned model, the problem of illustrating the effects of IL-2 on a growing tumour remains open. In this paper, we update the model of de Pillis et al. and then carefully identify appropriate values for the parameters of the new model according to recent empirical data. We determine new NK and tumour antigen-activated CD8 T-cell count equilibrium values; we complete IL-2 dynamics; and we modify the model in de Pillis et al. to allow for endogenous IL-2 production, IL-2-stimulated NK cell proliferation and IL-2-dependent CD8 T-cell self-regulations. Finally, we show that the potential patient-specific efficacy of immunotherapy may be dependent on experimentally determinable parameters

Seeking Bang-Bang Solutions of Mixed Immuno-Chemotherapy of Tumors

It is known that a beneficial cancer treatment approach for a single patient often involves the administration of more than one type of therapy. The question of how best to combine multiple cancer therapies, however, is still open. In this study, we investigate the theoretical interaction of three treatment types (two biological therapies and one chemotherapy) with a growing cancer, and present an analysis of an optimal control strategy for administering all three therapies in combination. In the situations with controls introduced linearly, we find that there are conditions on which the controls exist singularly. Although bang-bang controls (on-off) reflect the drug treatment approach that is often implemented clinically, we have demonstrated, in the context of our mathematical model, that there can exist regions on which this may not be the best strategy for minimizing a tumor burden. We characterize the controls in singular regions by taking time derivatives of the switching functions. We will examine these representations and the conditions necessary for the controls to be minimizing in the singular region. We begin by assuming only one of the controls is singular on a given interval. Then we analyze the conditions on which a pair and then all three controls are singular

Countermovement Jump Inter-Limb Asymmetries in Collegiate Basketball Players

The purpose of the present study was to establish the intrasession and intersession reliability of variables obtained from a force plate that was used to quantitate lower extremity inter-limb asymmetry during the bilateral countermovement jump (CMJ). Secondarily, a comparison was performed to determine the influence of the jump protocol CMJ with or without an arm swing (CMJ AS and CMJ NAS, respectively) on inter-limb asymmetries. Twenty-two collegiate basketball players performed three CMJ AS and three CMJ NAS on dual force platforms during two separate testing sessions. A majority of variables met the acceptable criterion of intersession and intrasession relative reliability (ICC > 0.700), while fewer than half met standards established for absolute reliability (CV < 10%). CMJ protocol appeared to influence asymmetries; Concentric Impulse-100 ms, Eccentric Braking Rate of Force Development, Eccentric Deceleration, and Force at Zero velocity were significantly di erent between jumping conditions (CMJAS versus CMJ NAS; p < 0.05). The present data establish the reliability and smallest worthwhile change of inter-limb asymmetries during the CMJ, while also identifying the influence of CMJ protocol on inter-limb asymmetries, which can be useful to practitioners and clinicians in order to e ectively monitor changes associated with performance, injury risk, and return-to-play strategies.Open Access fees paid for in whole or in part by the University of Oklahoma LibrariesYe

The Influence of Countermovement Jump Protocol on Reactive Strength Index Modified and Flight Time: Contraction Time in Collegiate Basketball Players

The purpose of the present investigation was to evaluate differences in Reactive Strength Index Modified (RSIMod) and Flight Time to Contraction Time Ratio (FT:CT) during the countermovement jump (CMJ) performed without the arm swing (CMJNAS) compared to the CMJ with the arm swing (CMJAS), while exploring the relationship within each variable between jump protocols. A secondary purpose sought to explore the relationship between RSIMod and FT:CT during both jump protocols. Twenty-two collegiate basketball players performed both three CMJNAS and three CMJAS on a force plate, during two separate testing sessions. RSIMod was calculated by the flight-time (RSIModFT) and impulse-momentum methods (RSIModIMP). CMJ variables were significantly greater during the CMJAS compared to CMJNAS (p < 0.001). There were large to very large correlations within each variable between the CMJAS and CMJNAS. There were significant positive correlations among RSIModFT, RSIModIMP, and FT:CT during both the CMJAS (r ≥ 0.864, p < 0.001) and CMJNAS (r ≥ 0.960, p < 0.001). These findings identify an increase in RSIMod or FT:CT during the CMJAS, that may provide independent information from the CMJNAS. In addition, either RSIMod or FT:CT may be utilized to monitor changes in performance, but simultaneous inclusion may be unnecessary.Conflicts of Interest The authors declare no conflict of interest. Funding This research received no external funding.Ye