Stability limits of minimum volume and breaking axisymmetric liquid bridges between unequal disks

This paper deals with the stability limits of minimum volume and the breaking of axisymmetric liquid columns held by capillary forces between two concentric,circular solid disk of different radii. The problem has been analyzed both theoreti-cally and experimentally. A theoretical analysis concerning the breaking of liquid bridges has been performed by using a one-dimensional slice model already used in liquid bridge problems. Experiments have been carried out by using milli-metric liquid bridges, and minimum volume stability limits as well as the volumes of the drops resulting after breaking have been measured for a large number of liquid bridge configurations. Experimental results being in agreement with theoretical prediction.

Non-Arrhenius kinetics for the loop closure of a DNA hairpin

Intramolecular chain diffusion is an elementary process in the conformational fluctuations of the DNA hairpin-loop. We have studied the temperature and viscosity dependence of a model DNA hairpin-loop by FRET (fluorescence resonance energy transfer) fluctuation spectroscopy (FRETfs). Apparent thermodynamic parameters were obtained by analyzing the correlation amplitude through a two-state model and are consistent with steady-state fluorescence measurements. The kinetics of closing the loop show non-Arrhenius behavior, in agreement with theoretical prediction and other experimental measurements on peptide folding. The fluctuation rates show a fractional power dependence (β = 0.83) on the solution viscosity. A much slower intrachain diffusion coefficient in comparison to that of polypeptides was derived based on the first passage time theory of SSS [Szabo, A., Schulten, K. & Schulten, Z. (1980) J. Chem. Phys. 72, 4350–4357], suggesting that intrachain interactions, especially stacking interaction in the loop, might increase the roughness of the free energy surface of the DNA hairpin-loop.

Search for very high energy gamma radiation from the radio bright region DR4 of the SNR G78.2+2.1

Data from the HEGRA air shower array are used to set an upper limit on the emission of gamma-radiation above 25 (18) TeV from the direction of the radio bright region DR4 within the SNR G78.2 + 2.1 of 2.5 (7.1). 10^-13 cm^-2 sec^-1. The shock front of SNR G78.2 + 2.1 probably recently overtook the molecular cloud Gong 8 which then acts as a target for the cosmic rays produced within the SNR, thus leading to the expectation of enhanced gamma-radiation. Using a model of Drury, Aharonian and Völk which assumes that SNRs are the sources of galactic cosmic rays via first order Fermi acceleration, we calculated a theoretical prediction for the gamma-ray flux from the DR4 region and compared it with our experimental flux limit. Our 'best estimate' value for the predicted flux lies a factor of about 18 above the upper limit for gamma-ray energies above 25 TeV. Possible reasons for this discrepancy are discussed.

Wolbachia transfer from Rhagoletis cerasi to Drosophila simulans: Investigating the outcomes of host-symbiont coevolution

Wolbachia is an endosymbiont of diverse arthropod lineages that can induce various alterations of host reproduction for its own benefice. Cytoplasmic incompatibility (CI) is the most common phenomenon, which results in embryonic lethality when males that bear Wolbachia are mated with females that do not. In the cherry fruit fly, Rhagoletis cerasi, Wolbachia seems to be responsible for previously reported patterns of incompatibility between populations. Here we report on the artificial transfer of two Wolbachia variants (wCer1 and wCer2) from R. cerasi into Drosophila simulans, which was performed with two major goals in mind: first, to isolate wCer1 from wCer2 in order to individually test their respective abilities to induce Cl in the new host; and, second, to test the theoretical prediction that recent Wolbachia-host associations should be characterized by high levels of CI, fitness costs to the new host, and inefficient transmission from mothers to offspring. wCer1 was unable to develop in the new host, resulting in its rapid loss after successful injection, while wCer2 was established in the new host. Transmission rates of wCer2 were low, and the infection showed negative fitness effects, consistent with our prediction, but CI levels were unexpectedly lower in the new host. Based on these parameter estimates, neither wCer1 nor wCer2 could be naturally maintained in D. simulans. The experiment thus suggests that natural Wolbachia transfer between species might be restricted by many factors, should the ecological barriers be bypassed.

Studies of the drying of particulate slurries

The literature relating to the drying characteristics of pure liquid drops and particulate slurry drops has been reviewed. The experimental investigation was, therefore, divided into three parts: Pure water drops, Aqueous sodium sulphate decahydrate drops, and, Slurry drops from nine detergent formulations. The value of the constant,'Ψ, reported by Ranz and Marshall, was found to be temperature dependent. In the temperature range o 26.5≤T≤118.5°C,Ψ , for pure water drops, varied between 0.38 and 0.47. A revised correlation of the mass transfer coefficients is therefore proposed.  A mathematical model for estimating the variation of crust thickness, for aqueous sodium sulphate drops, with time is proposed: β = R _ {R3 - ( 1.5G/πCo ) ( ΔHD - ΔHU) Δ} 1/3 Experimental crust thickness evaluated from stereoscan micrographs showed good agreement with theoretical prediction. It has been shown that drying characteristics of detergent drops can be evaluated from the porosity:thickness ratio, {ε/\β}. Formulations having large {ε/β I-ratios dry better than those with smaller values. The agreement between the experimental and theoretical mass transfer coefficients shows, in addition to the above correlation, that the overall mass transfer coefficient can be predicted from the expression1/K = 1/K + β/DMε 1.5 The crust is the controlling resistance to transfer in particulate slurry drops. For aqueous sodium sulphate drops, the crust provides 64.2% of the total resistance while for detergents with thicker, but less porous crusts, the value is 97.5%.

The transition from severe to mild wear in law alloy steel

The wear rates of sliding surfaces are significantly reduced if mild oxidational wear can be encouraged. It is hence of prime importance in the interest of component life and material conservation to understand the factors necessary to promote mild, oxidational wear, The present work investigates the fundamental mechanism of the running-in wear of BS EN 31!EN 8 steel couples. under various conditions of load. speed and test duration. Unidirectional sliding experiments were carried out on a pin-on~disc wear machine where frictional force, wear rate, temperature and contact resistance were continuously monitored during each test. Physical methods of analysis (x-ray, scanning electron microscopy etc.) were used to examine the wear debris and worn samples. The wear rate versus load curves revealed mild wear transitions, which under long duration of running, categorized mild wear into four distinct regions.α-Fe20s. Fe304, FeO and an oxide mixture were the predominant oxides in four regions of oxidational wear which were identified above the Welsh T2 transition. The wear curves were strongly effected by the speed and test duration. A surface model was used to calculate the surface parameters, and the results were found to be comparable with the experimentally observed parameters. Oxidation was responsible for the transition from severe to mild wear at a load corresponding to the Welsh T2 transition. In the running-in period sufficient energy input and surface hardness enabled oxide growth rate to increase and eventually exceeded the rate of removal, where mild wear ensued. A model was developed to predict the wear volume up to the transition. Remarkable agreement was found between the theoretical prediction and the experimentally-measured values. The oxidational mechanjsm responsible for transitjon to mild wear under equilibrium conditions was related to the formation of thick homogenous oxide plateaux on subsurface hardened layers, FeO was the oxide formed initially at the onset of mild wear but oxide type changed.during the total running period to give an equilibrium oxide whose nature depended on the loads applied.

Noise generated at the tyre/road interface

The work described in this thesis is directed towards the reduction of tyre/road interface noise and embodies a study of the factors involved in its generation. These factors comprise: (a) materials and construction of tyres and road surfaces (b) the spectral distribution of the noise. The importance of this work has become greater with reduction in engine noise. A review of the literature shows what has been achieved so far, and stresses the importance of maintaining other desirable tyre properties such as adhesion in wet conditions. The work has involved an analysis of mechanical factors in tyre construction and the behaviour of road surfaces. Measurements on noise have been carried out under practical conditions and also on replica surfaces in the laboratory, and in addition tests of wet road adhesion have been carried out with a variety of road surfaces. Consideration has been given to the psychological effects of the spectral distribution of noise. A major part of the work under-taken has been the development of a computer program, the results of which have made it possible to design a tyre tread block pattern to give an optimum spectral distribution. Sample tyres built to this design have been subjected to noise measurements and these have been shown to agree closely with the theoretical prediction and other properties of this tyre have proved to be satisfactory.

Accurate estimation of isoelectric point of protein and peptide based on amino acid sequences

Motivation: In any macromolecular polyprotic system - for example protein, DNA or RNA - the isoelectric point - commonly referred to as the pI - can be defined as the point of singularity in a titration curve, corresponding to the solution pH value at which the net overall surface charge - and thus the electrophoretic mobility - of the ampholyte sums to zero. Different modern analytical biochemistry and proteomics methods depend on the isoelectric point as a principal feature for protein and peptide characterization. Protein separation by isoelectric point is a critical part of 2-D gel electrophoresis, a key precursor of proteomics, where discrete spots can be digested in-gel, and proteins subsequently identified by analytical mass spectrometry. Peptide fractionation according to their pI is also widely used in current proteomics sample preparation procedures previous to the LC-MS/MS analysis. Therefore accurate theoretical prediction of pI would expedite such analysis. While such pI calculation is widely used, it remains largely untested, motivating our efforts to benchmark pI prediction methods. Results: Using data from the database PIP-DB and one publically available dataset as our reference gold standard, we have undertaken the benchmarking of pI calculation methods. We find that methods vary in their accuracy and are highly sensitive to the choice of basis set. The machine-learning algorithms, especially the SVM-based algorithm, showed a superior performance when studying peptide mixtures. In general, learning-based pI prediction methods (such as Cofactor, SVM and Branca) require a large training dataset and their resulting performance will strongly depend of the quality of that data. In contrast with Iterative methods, machine-learning algorithms have the advantage of being able to add new features to improve the accuracy of prediction. Contact: yperez@ebi.ac.uk Availability and Implementation: The software and data are freely available at https://github.com/ypriverol/pIR. Supplementary information: Supplementary data are available at Bioinformatics online.

Hydrogen(electron-deuteron) studies of the deuteron at high squared momentum transfer

A high resolution study of the quasielastic 2 H(e, e'p)n reaction was performed in Hall A at the Thomas Jefferson Accelerator Facility in Newport News, Virginia. The measurements were performed at a central momentum transfer of : q: ∼ 2400 MeV/c, and at a central energy transfer of ω ∼ 1500 MeV, a four momentum transfer Q2 = 3.5 (GeV/c)2, covering missing momenta from 0 to 0.5 GeV/c. The majority of the measurements were performed at Φ = 180° and a small set of measurements were done at Φ = 0°. The Hall A High Resolution Spectrometers (HRS) were used to detect coincident electrons and protons, respectively. Absolute 2H(e, e'p) n cross sections were obtained as a function of the recoiling neutron scattering angle with respect to [special characters omitted]. The experimental results were compared to a Plane Wave Impulse Approximation (PWIA) model and to a calculation that includes Final State Interaction (FSI) effects. Experimental 2H(e, e'p)n cross sections were determined with an estimated systematic uncertainty of 7%. The general features of the measured cross sections are reproduced by Glauber based calculations that take the motion of the bound nucleons into account (GEA). Final State Interactions (FSI) contributions were found to depend strongly on the angle of the recoiling neutron with respect to the momentum transfer and on the missing momentum. We found a systematic deviation of the theoretical prediction of about 30%. At small &thetas; nq (&thetas;nq < 60°) the theory overpredicts the cross section while at large &thetas; nq (&thetas;nq > 80°) the theory underestimates the cross sections. We observed an enhancement of the cross section, due to FSI, of about 240%, as compared to PWIA, for a missing momentum of 0.4 GeV/c at an angle of 75°. For missing momentum of 0.5 GeV/c the enhancement of the cross section due to the same FSI effects, was about 270%. This is in agreement with GEA. Standard Glauber calculations predict this large contribution to occur at an angle of 90°. Our results show that GEA better describes the 2H(e, e'p)n reaction.

Experimental deuteron momentum distributions with reduced final state interactions

This dissertation presents a study of the D( e, e′p)n reaction carried out at the Thomas Jefferson National Accelerator Facility (Jefferson Lab) for a set of fixed values of four-momentum transfer Q 2 = 2.1 and 0.8 (GeV/c)2 and for missing momenta pm ranging from pm = 0.03 to pm = 0.65 GeV/c. The analysis resulted in the determination of absolute D(e,e′ p)n cross sections as a function of the recoiling neutron momentum and it's scattering angle with respect to the momentum transfer [vector] q. The angular distribution was compared to various modern theoretical predictions that also included final state interactions. The data confirmed the theoretical prediction of a strong anisotropy of final state interaction contributions at Q2 of 2.1 (GeV/c)2 while at the lower Q2 value, the anisotropy was much less pronounced. At Q2 of 0.8 (GeV/c)2, theories show a large disagreement with the experimental results. The experimental momentum distribution of the bound proton inside the deuteron has been determined for the first time at a set of fixed neutron recoil angles. The momentum distribution is directly related to the ground state wave function of the deuteron in momentum space. The high momentum part of this wave function plays a crucial role in understanding the short-range part of the nucleon-nucleon force. At Q2 = 2.1 (GeV/c)2, the momentum distribution determined at small neutron recoil angles is much less affected by FSI compared to a recoil angle of 75°. In contrast, at Q2 = 0.8 (GeV/c)2 there seems to be no region with reduced FSI for larger missing momenta. Besides the statistical errors, systematic errors of about 5–6 % were included in the final results in order to account for normalization uncertainties and uncertainties in the determi- nation of kinematic veriables. The measurements were carried out using an electron beam energy of 2.8 and 4.7 GeV with beam currents between 10 to 100 &mgr; A. The scattered electrons and the ejected protons originated from a 15cm long liquid deuterium target, and were detected in conicidence with the two high resolution spectrometers of Hall A at Jefferson Lab.^

A search for hep solar neutrinos at the Sudbury Neutrino Observatory

Thesis (Ph.D.)--University of Washington, 2016-08

Phase noise and spur reduction in an array of direct digital synthesizers

Many applications, including communications, test and measurement, and radar, require the generation of signals with a high degree of spectral purity. One method for producing tunable, low-noise source signals is to combine the outputs of multiple direct digital synthesizers (DDSs) arranged in a parallel configuration. In such an approach, if all noise is uncorrelated across channels, the noise will decrease relative to the combined signal power, resulting in a reduction of sideband noise and an increase in SNR. However, in any real array, the broadband noise and spurious components will be correlated to some degree, limiting the gains achieved by parallelization. This thesis examines the potential performance benefits that may arise from using an array of DDSs, with a focus on several types of common DDS errors, including phase noise, phase truncation spurs, quantization noise spurs, and quantizer nonlinearity spurs. Measurements to determine the level of correlation among DDS channels were made on a custom 14-channel DDS testbed. The investigation of the phase noise of a DDS array indicates that the contribution to the phase noise from the DACs can be decreased to a desired level by using a large enough number of channels. In such a system, the phase noise qualities of the source clock and the system cost and complexity will be the main limitations on the phase noise of the DDS array. The study of phase truncation spurs suggests that, at least in our system, the phase truncation spurs are uncorrelated, contrary to the theoretical prediction. We believe this decorrelation is due to the existence of an unidentified mechanism in our DDS array that is unaccounted for in our current operational DDS model. This mechanism, likely due to some timing element in the FPGA, causes some randomness in the relative phases of the truncation spurs from channel to channel each time the DDS array is powered up. This randomness decorrelates the phase truncation spurs, opening the potential for SFDR gain from using a DDS array. The analysis of the correlation of quantization noise spurs in an array of DDSs shows that the total quantization noise power of each DDS channel is uncorrelated for nearly all values of DAC output bits. This suggests that a near N gain in SQNR is possible for an N-channel array of DDSs. This gain will be most apparent for low-bit DACs in which quantization noise is notably higher than the thermal noise contribution. Lastly, the measurements of the correlation of quantizer nonlinearity spurs demonstrate that the second and third harmonics are highly correlated across channels for all frequencies tested. This means that there is no benefit to using an array of DDSs for the problems of in-band quantizer nonlinearities. As a result, alternate methods of harmonic spur management must be employed.

Resonant five-body recombination in an ultracold gas of bosonic atoms

We combine theory and experiment to investigate five-body recombination in an ultracold gas of atomic cesium at negative scattering length. A refined theoretical model, in combination with extensive laboratory tunability of the interatomic interactions, enables the five-body resonant recombination rate to be calculated and measured. The position of the new observed recombination feature agrees with a recent theoretical prediction and supports the prediction of a family of universal cluster states at negative a that are tied to an Efimov trimer.

Ocean bottom pressure records from the Cascadia array and short surface gravity waves

The ocean bottom pressure records from eight stations of the Cascadia array are used to investigate the properties of short surface gravity waves with frequencies ranging from 0.2 to 5 Hz. It is found that the pressure spectrum at all sites is a well-defined function of the wind speed U10 and frequency f, with only a minor shift of a few dB from one site to another that can be attributed to variations in bottom properties. This observation can be combined with the theoretical prediction that the ocean bottom pressure spectrum is proportional to the surface gravity wave spectrum E(f) squared, times the overlap integral I(f) which is given by the directional wave spectrum at each frequency. This combination, using E(f) estimated from modeled spectra or parametric spectra, yields an overlap integral I(f) that is a function of the local wave age inline image. This function is maximum for f∕fPM = 8 and decreases by 10 dB for f∕fPM = 2 and f∕fPM = 30. This shape of I(f) can be interpreted as a maximum width of the directional wave spectrum at f∕fPM = 8, possibly equivalent to an isotropic directional spectrum, and a narrower directional distribution toward both the dominant low frequencies and the higher capillary-gravity wave frequencies.

Prediction of Multi-Target Networks of Neuroprotective Compounds with Entropy Indices and Synthesis, Assay, and Theoretical Study of New Asymmetric 1,2-Rasagiline Carbamates

In a multi-target complex network, the links (L-ij) represent the interactions between the drug (d(i)) and the target (t(j)), characterized by different experimental measures (K-i, K-m, IC50, etc.) obtained in pharmacological assays under diverse boundary conditions (c(j)). In this work, we handle Shannon entropy measures for developing a model encompassing a multi-target network of neuroprotective/neurotoxic compounds reported in the CHEMBL database. The model predicts correctly >8300 experimental outcomes with Accuracy, Specificity, and Sensitivity above 80%-90% on training and external validation series. Indeed, the model can calculate different outcomes for >30 experimental measures in >400 different experimental protocolsin relation with >150 molecular and cellular targets on 11 different organisms (including human). Hereafter, we reported by the first time the synthesis, characterization, and experimental assays of a new series of chiral 1,2-rasagiline carbamate derivatives not reported in previous works. The experimental tests included: (1) assay in absence of neurotoxic agents; (2) in the presence of glutamate; and (3) in the presence of H2O2. Lastly, we used the new Assessing Links with Moving Averages (ALMA)-entropy model to predict possible outcomes for the new compounds in a high number of pharmacological tests not carried out experimentally.