Separation Threshold Research Articles

Electromagnetic processes in silver isotopes

Peculiarities of electromagnetic interactions in silver isotopes are considered. Excited states of Ag isotopes are studied as a function of the mass number A = 95–117. Low-lying excited states reveal clear features that are specific for rotational spectra for the energies E < 4–5 MeV. In the energy domain above the nucleon separation threshold of 5–10 MeV, single-particle excited states overlap and produce a continuous spectrum. For energies E = 10–35 MeV, excitation of giant dipole resonance plays the most important role in Ag isotopes. Experimental data on the cross sections of photonuclear reactions in Ag isotopes are analyzed.

Continuous Theta Burst Stimulation Over the Dorsolateral Prefrontal Cortex and the Pre-SMA Alter Drift Rate and Response Thresholds Respectively During Perceptual Decision-Making.

The speed-accuracy trade-off (SAT) refers to the balancing of speed versus accuracy during decision-making. SAT is very commonly investigated with perceptual decision-making tasks such as the moving dots task (MDT). The dorsolateral prefrontal cortex (DLPFC) and the pre-supplementary motor area (pre-SMA) are two brain regions considered to be involved in the control of SAT. The study tested whether the DLPFC and the pre-SMA play an essential role in the control of SAT. We hypothesized that continuous theta burst stimulation (cTBS) over the right DLPFC would primarily alter the rate of accumulation of evidence, whereas stimulation of the pre-SMA would influence the threshold for reaching a decision. Fifteen (5 females; mean age = 30, SD =5.40) healthy volunteers participated in the study. We used two versions of the MDT and cTBS over the right DLPFC, pre-SMA and sham stimulation. The drift diffusion model was fit to the behavioural data (reaction time and error rate) in order to calculate the drift rate, boundary separation (threshold) and non-decision time. cTBS over the right DLPFC decreased the rate of accumulation of evidence (i.e. the drift rate from the diffusion model) in high (0.35 and 0.5) but not in low coherence trials. cTBS over the pre-SMA changed the boundary separation/threshold required to reach a decision on accuracy, but not on speed trials. The results suggest for the first time that both the DLPFC and the pre-SMA make essential but distinct contributions to the modulation of SAT.

A New Wavelet Denoising Method for Selecting Decomposition Levels and Noise Thresholds.

A new method is presented to denoise 1-D experimental signals using wavelet transforms. Although the state-of- the-art wavelet denoising methods perform better than other denoising methods, they are not very effective for experimental signals. Unlike images and other signals, experimental signals in chemical and biophysical applications for example, are less tolerant to signal distortion and under-denoising caused by the standard wavelet denoising methods. The new method 1) provides a method to select the number of decomposition levels to denoise, 2) uses a new formula to calculate noise thresholds that does not require noise estimation, 3) uses separate noise thresholds for positive and negative wavelet coefficients, 4) applies denoising to the Approximation component, and 5) allows the flexibility to adjust the noise thresholds. The new method is applied to continuous wave electron spin resonance (cw-ESR) spectra and it is found that it increases the signal-to-noise ratio (SNR) by more than 32 dB without distorting the signal, whereas standard denoising methods improve the SNR by less than 10 dB and with some distortion. Also, its computation time is more than 6 times faster.

The impact of subsidies on overcapacity: A comparison of wind and solar energy companies in China

Determining the level of subsidy is an important measure in addressing overcapacity in Chinese renewable energy enterprises. In this article, we employ a threshold regression model to analyze the impacts of government subsidies on the overcapacity of wind and solar energy companies. Our findings indicate the separate subsidy thresholds for solar and wind energy companies. The results reveal that even where the subsidy falls into a relatively effective interval, it will still intensify the risk of overcapacity in solar energy companies, but can help address overcapacity in the wind energy companies. The paper concludes that the level of subsidies should be unique for each industry, and suggests a prudent reform of the subsidy policy for the solar energy enterprises.

Crash protectiveness to occupant injury and vehicle damage: An investigation on major car brands

This study sets out to investigate vehicles’ crash protectiveness on occupant injury and vehicle damage, which can be deemed as an extension of the traditional crash worthiness. A Bayesian bivariate hierarchical ordered logistic (BVHOL) model is developed to estimate the occupant protectiveness (OP) and vehicle protectiveness (VP) of 23 major car brands in Florida, with considering vehicles’ crash aggressivity and controlling external factors. The proposed model not only takes over the strength of the existing hierarchical ordered logistic (HOL) model, i.e. specifying the order characteristics of crash outcomes and cross-crash heterogeneities, but also accounts for the correlation between the two crash responses, driver injury and vehicle damage. A total of 7335 two-vehicle-crash records with 14,670 cars involved in Florida are used for the investigation. From the estimation results, it's found that most of the luxury cars such as Cadillac, Volvo and Lexus possess excellent OP and VP while some brands such as KIA and Saturn perform very badly in both aspects. The ranks of the estimated safety performance indices are even compared to the counterparts in Huang et al. study [Huang, H., Hu, S., Abdel-Aty, M., 2014. Indexing crash worthiness and crash aggressivity by major car brands. Safety Science 62, 339–347]. The results show that the rank of occupant protectiveness index (OPI) is relatively coherent with that of crash worthiness index, but the ranks of crash aggressivity index in both studies is more different from each other. Meanwhile, a great discrepancy between the OPI rank and that of vehicle protectiveness index is found. What's more, the results of control variables and hyper-parameters estimation as well as comparison to HOL models with separate or identical threshold errors, demonstrate the validity and advancement of the proposed model and the robustness of the estimated OP and VP.

Removal of Fluoride and Hardness in Dietary Intake (water) in Chronic Kidney Disease of unknown Etiology (CKDu) Prevalent Areas by Domestic Reverse Osmosis Units

The origin of Chronic Kidney Disease of unknown etiology (CKDu) that is rapidly invadingthe dry zone of Sri Lanka has not yet been identified. However, occurrence of the disease isthought to be linked with excess levels of fluoride and hardness in drinking water. Hence, thestudy herein focuses to evaluate the suitability of domestic Reverse Osmosis (RO) units;which introduced in CKDu affected areas to remove excess fluoride and hardness.Accordingly, the drinking water quality in CKDu prevalent areas in terms of fluoride andhardness was simulated in the laboratory and the removal of aforesaid constituents usingdomestic ROs was investigated.According to water quality analyses, domestic RO units effectively removed hardness even atextremely high initial concentrations, such as 1,730 mg/L (as CaCO3). Excessive removal ofCalcium and Magnesium by the RO units was observed, thus remineralization of thepermeate up to 80-100 mg/L as CaCO3 is required to ensure health benefits. Meanwhile,fluoride removal was observed to be highly dependent upon initial fluoride and hardnessconcentrations. It was not possible to suggest an „optimum removal level‟ for fluoride, wherepermeate fluoride concentration exceeded the maximum permissible WHO Drinking WaterGuideline value of 1.5 mg/L. However, it may arise at a point where fluoride and hardnessconcentrations in raw water fall within 1.7-3.5 mg/L and 570-1,130 mg/L as CaCO3,respectively.Plausible reasons for ineffective removal of fluoride could be the relatively small size andlow ionic charge of fluoride. Additionally, high concentration of heavy ions may interferewith fluoride adsorption of activated carbon filter in the domestic RO unit. Effective fluorideremoval could be achieved by adopting appropriate pre-treatment methods for hardnessremoval. Separate threshold levels for fluoride and hardness levels in drinking water shouldbe defined, especially for CKDu patients.Keywords: Chronic Kidney Disease, Domestic reverse osmosis units, Fluoride, Hardness

Amplitude Modulation Detection and Speech Recognition in Late-Implanted Prelingually and Postlingually Deafened Cochlear Implant Users.

Many late-implanted prelingually deafened cochlear implant (CI) patients struggle to obtain open-set speech understanding. Because it is known that low-frequency temporal-envelope information contains important cues for speech understanding, the goal of this study was to compare the temporal-envelope processing abilities of late-implanted prelingually and postlingually deafened CI users. Furthermore, the possible relation between temporal processing abilities and speech recognition performances was investigated. Amplitude modulation detection thresholds were obtained in eight prelingually and 18 postlingually deafened CI users, by means of a sinusoidally modulated broadband noise carrier, presented through a loudspeaker to the CI user's clinical device. Thresholds were determined with a two-down-one-up three-interval oddity adaptive procedure, at seven modulation frequencies. Phoneme recognition (consonant-nucleus-consonant [CNC]) scores (percentage correct at 65 dB SPL) were gathered for all CI users. For the prelingually deafened group, scores on two additional speech tests were obtained: (1) a closed-set monosyllable-trochee-spondee test (percentage correct scores at 65 dB SPL on word recognition and categorization of the suprasegmental word patterns), and (2) a speech tracking test (number of correctly repeated words per minute) with texts specifically designed for this population. The prelingually deafened CI users had a significantly lower sensitivity to amplitude modulations than the postlingually deafened CI users, and the attenuation rate of their temporal modulation transfer function (TMTF) was greater. None of the prelingually deafened CI users were able to detect modulations at 150 and 200 Hz. High and significant correlations were found between the results on the amplitude modulation detection test and CNC phoneme scores, for the entire group of CI users. In the prelingually deafened group, CNC phoneme scores, word scores on the monosyllable-trochee-spondee test, and speech tracking scores correlated significantly with the mean amplitude modulation detection threshold of the modulation frequencies between 5 and 100 Hz and with almost all separate amplitude modulation thresholds. High correlations with these speech measures were also found for the attenuation rate of and the surface area below the TMTF. In postlingually deafened CI users, CNC phoneme scores only correlated significantly with the 100-Hz and 150-Hz amplitude modulation thresholds, as well as with the attenuation rate of and surface area below the TMTF. Prelingually deafened CI users were less sensitive to temporal modulations than postlingually deafened CI users, and the attenuation rate of their TMTF was steeper. For all CI users, subjects with better amplitude modulation detection skills tended to score better on measures of speech understanding. Significant correlations with low modulation frequencies were found only for the prelingually deafened CI users and not for the postlingually deafened CI users.

Nanocrystalline sputter-deposited ZnMgO:Al transparent p-type electrode in GaN-based 385nm UV LED for significant emission enhancement

Abstract We demonstrate nanocrystalline ZnMgO:Al transparent conducting films grown by room temperature magnetron sputtering. Unlike in the usual ZnMgO films grown by sputtering, the crystal orientation perpendicular to the substrate surface is strongly disrupted with the addition of Mg, even well below the phase separation threshold of Mg/(Mg + Zn) = 0.43. We argue that the presence of Al in the films promotes disoriented growth. Using transmission, Rutherford Backscattering Spectroscopy and electron microscopy measurements, we prove that not all Mg in the films substitutes Zn in the ZnO lattice, but also forms of precipitates. We apply the highest transmission films as contact electrodes to the p-GaN layer in a GaN-based 385 nm UV LED structure. By replacing the common opaque Ni/Au ohmic contact to p-GaN in ring geometry by a circular ZnMgO:Al electrode we obtain a 250% increase in irradiated power, which is also 148% higher than when Ni/Al is replaced by ZnO:Al.

Mo1107 Differences of LES Impedance Planimetry in Laparoscopic Sleeve Gastrectomy Versus Laparoscopic Conversion From Gastric Banding to Sleeve Gastrectomy

Background:Among the extra-esophagealmanifestations of GERD, dental erosion is currently considered one of the most frequent. These dental erosions have a characteristic localization and may sometimes be the first symptom of the GERD. Wireless nasopharyngeal pH metry (ResTech pH probe) is a minimally invasive device for detection of oropharyngeal acid reflux.Aim: To ascertain whether adult patients with dental erosions (DE) have a higher incidence of reflux into the nasopharynx compared with controls using the ResTech phH probe.Materials and methods: A cross-sectional study was conducted among patients whom attend to the dental service at the Health Services Research Center in our institution. Dental erosion was classified by means of severity and anatomic location, according to the Eccles and Jenkins dental (0=no erosion present [control group];grade 1=loss of surface detail, with change confined to the enamel; grade 2=exposure of dentin affecting less than one third of the crown; and 3=exposure of dentin affecting one third or more of the crown). In all subjects eating habits and dental medical history (CPO index) was obtained and GERD symptoms were assessed using the GERD-Q questionnaire and the ISR index. In all subjects a Restech Dx-pH was performed and separate pH thresholds of 0.05). DE subjects had a higher prevalence of positive GERD-Q questionnaires (92% vs 42%, p=0.002) and also higher scores (45 vs 6, p=0.01). DE subjects had more number of reflux episodes at pH 5.0 and 4.5 compared to HC (p<0.05, Figure) . A positive correlation was found between the # of reflux episodes (pH 5.0 and 4.5) with the GERD-Q score (p=0.50 and 0.57). Conclusion: A relationship between DE and GERD was established by precise and accurate measurement of pH changes in the oral cavity using ResTech pH metry. This method could be an ideal tool for evaluation of GRED as cause of DE.

An adaptive procedure for estimating the auditory-filter phase response

Current techniques for psychophysical estimates of the phase curvature of the basilar membrane rely on laborious data collection. For each point on the basilar membrane a separate threshold estimate — more commonly several estimates — must be found for each phase relationship. This practically limits the precision of the estimates and the number of subjects for whom estimates may be obtained. Here, we propose a rudimentary adaptive technique for rapidly estimating the phase curvature of the basilar membrane psychophysically. Consistent with the extant data the procedure assumes that the underlying threshold versus masker curvature function has a U shape. Rather than find thresholds at each value of masker curvature, the procedure seeks out only the value which produces the least masking. It does so by dropping the signal level until only three adjacent masker curvature values fail to mask the signal. New upper and lower boundaries for the masker curvature are then set, the step size between masker curvature values is reduced, and the previous steps are repeated. We present a comparison of the estimates produced by the conventional techniques and the proposed adaptive technique, as well as their relative efficiencies.

Search for E1 strength in 62,64Fe around the threshold

The structure and nature of the pygmy dipole resonance (PDR) states below and above the neutron threshold is a recent open problem, particularly in exotic, neutron rich nuclei. Present experimental observations give only limited information on this subject. New experiments using different methods are needed. A recent measurement at the GSI laboratories on 62,64Fe with the PRESPEC (2014) setup, following a past experiment with the RISING (2005) setup on 68Ni, will contribute to solve the open questions. The setup located at GSI consists of the segmented HPGe detector array AGATA, scintillators (HECTOR), an Energy Loss / Total Energy time of flight measuring detector system called LYCCA and the fragment separator (FRS) apparatus. The experiment is based on relativistic Coulomb excitation together with the detection of the incoming and outgoing particles event by event. The detection of the produced y-rays in the reactions, provides insight into the problem of the electric dipole response and E1 strength distribution around particle separation threshold.

Visualization of supersonic flow around a sharp-edged, sub-boundary-layer protuberance

Innovations in conventional surface and planar laser scattering visualizations revealed complex structures in the Mach 2.5 flow past a sharp-edged, sub-boundary-layer ramp with swept sides that is one type of micro vortex generator (MVG). The incoming flow separated over the leading edge despite the ramp angle being below the threshold for incipient separation. The separation produced a weak trailing horseshoe vortex system. The flow over the top of the MVG separated off the slant edges to produce a large primary vortex pair. Extra details were revealed at the trailing edge with at least two pairs of singularities. Vortex filaments spring from these singularities. Symmetry breaking from the confluence of the two primary vortices was observed as an unsteady wake to result in a train of possibly ring or hairpin vortices trailing downstream.

First evidence of low energy enhancement in Ge isotopes

The γ-strength functions and level densities of 73,74 Ge have been extracted from particle-γ coincidence data using the Oslo method. In addition the γ-strength function of 74 Ge above the neutron separation threshold, Sn = 10.196 MeV has been extracted from photoneutron measurements. When combined, these two experiments give a γ-strength function covering the energy range of ∼1-13 MeV for 74 Ge. This thorough investigation of 74 Ge is a part of an international campaign to study the previously reported low energy enhancement in this mass region in the γ-strength function from ∼3 MeV towards lower γ energies. The obtained data show that both 73,74 Ge display an increase in strength at low γ energies.

87Y(n,γ) and89,90Zr(n,γ) cross sections from a surrogate reaction approach

The surrogate reaction approach is an indirect method for determining nuclear reaction cross sections which cannot be measured directly or predicted reliably. While recent studies demonstrated the validity of the surrogate reaction approach for studying fission cross sections for short-lived actinides, its applicability for radiative neutron capture reactions ((n,γ)) is still under investigation. We studied the γ decay of excited 88 Y and 90,91 Zr nuclei produced by 89 Y(p,d), 91 Zr(p,d), and 92 Zr(p,d) reactions, respectively, in order to infer the 87 Y(n,γ) and 89, 90 Zr(n,γ) cross sections. The experiments were carried out at the K150 Cyclotron facility at Texas A&M University with a 28.5-MeV proton beam. The reaction deuterons were measured at forward angles of 25-60° with the array of three segmented Micron S2 silicon detectors. The compound nuclei with energies up to a few MeV above the neutron separation thresholds were populated. The coincident γ-rays were measured with the array of five Compton-suppressed HPGe clover detectors.

Clinical applications of internal heat source analysis for breast cancer identification.

Nondestructive preoperative breast imaging techniques are widely used for breast cancer testing and diagnosis. This study aimed to evaluate the feasibility and efficacy of quantitative diagnosis via the thermal analysis of abnormal metabolism. Nine hundred forty-eight women who underwent breast biopsy from 2009 to 2013 were investigated. Thermal analysis was used to calculate the internal heat source (i.e., tumor) thermal power for each participant. The applicability and effectiveness of our approach were estimated using the chi-square test, kappa statistics (k), and odds ratios (OR). Breast density and tumor size were considered during this estimation. A thermal power q = 0.2 w was determined as the optimal separation threshold between breast cancer and benign disease. Moreover, good agreement (k = 0.837) with the gold-standard assessment (breast biopsy) was confirmed in 93.2% of the patients (N = 884/948), and the sensitivity and specificity were 94.2 and 92.9%, respectively. The results also found no significant differences in methodological accuracy between the fatty and dense breasts (OR = 1.194, P = 0.524). Furthermore, after dividing the cohort into three groups according to tumor size (T1: <2 cm; T2: 2 to 5 cm; T3: >5 cm), the tumor size had no effect on the proposed method (ORs = 1, P = 0.724). Internal heat source analysis can feasibly and efficiently distinguish between breast cancer and benign disease.

Photoneutron cross section measurements on Sm isotopes

The Extreme Light Infrastructure - Nuclear Physics, one of the three pillars of the Extreme Light Infrastructure Pan-European initiative, is a new large scale facility dedicated to nuclear physics with extreme electromagnetic fields. ELI-NP will host two 10 PW lasers and a very brilliant Gamma beam system with unprecedented intensity and energy resolution parameters. We propose to perform photon induced nuclear reactions using the very brilliant γ -ray beams provided by the Gamma beam system to examine in detail the photon absorption process and its decay modes. Here the experimental program related to nuclear research on reactions above the neutron separation threshold, which is under preparation at ELI-NP, is presented.

Dipole strength distributions from HIGS Experiments

A series of photon scattering experiments has been performed on the double-beta decay partners 76 Ge and 76 Se, in order to investigate their dipole response up to the neutron separation threshold. Gamma-ray beams from bremsstrahlung at the S-DALINAC and from Compton-backscattering at HIGS have been used to measure absolute cross sections and parities of dipole excited states, respectively. The HIGS data allows for indirect measurement of averaged branching ratios, which leads to significant corrections in the observed excitation cross sections. Results are compared to statistical calculations, to test photon strength functions and the Axel-Brink hypothesis.

Nuclear spectroscopy of 40–48Ca isotopes

The nature of the excited states of the 40–48Ca isotopes is analyzed in the region of energies below the nucleon separation threshold. A peculiar feature of the 40–48Ca isotopes is the predominant filling of the 1f 7/2 neutron shell. Interaction between the neutrons of the 1f 7/2 shell and the nucleons of the 1d2s core results in formation of multiparticle excited states with a few vacancies in the 1d2s shell. The energies of single-particle proton states in the 40–48Ca isotopes are calculated using the Hartree-Fock potential with the Skyrme potential. The manner in which the energy of single-particle states varies, the magic numbers N = 20, 28 are formed, and the charge and nucleon density vary in the 40–48Ca isotopes as the neutron number increases from 20 to 28 is shown. Coherent interactions of the 1f 7/2 shell and 1d2s core nucleons also manifest themselves in the region above the nucleon separation threshold, leading to the configuration and isospin splitting of the GDR.

Multidecadal Changes in the Frequency and Ambient Conditions of Warm Season Convective Storms over the Northeastern United States

Abstract Long-term changes in warm season (April–September) convective storm frequency over the northeastern United States (NEUS) and the environmental conditions favoring such storms are explored from 1979 to 2010. Linear discriminant analysis (LDA) was used to create thresholds for predicting annual warm season convective storm frequency over various small regions of the NEUS by relating the convective precipitation fields from the North American Regional Reanalysis (NARR) and the Climate Forecast System Reanalysis (CFSR) along with reflectivity data from the National Operational Weather Radar (NOWrad) archive at 2-km grid spacing from 1996 to 2006 to convective parameters in the reanalyses. On average, convective frequency is greatest across inland areas of the NEUS, particularly southern Pennsylvania, with a sharp decrease along the immediate coast. Across western Pennsylvania convective storm frequency has significantly (p &amp;lt; 0.01) decreased from 1979 to 2010, while closer to the coast convective frequency has increased slightly. There has also been a corresponding trend in warm season convective precipitation amounts, with decreasing amounts over inland Pennsylvania and increasing amounts near the coast. This general pattern of inland decreases and coastal increases is largely related to trends in low-level instability, which are attributable mainly to changes in low-level moisture. Analyzing convective parameters over small regions is an important consideration for future climate studies of convection, since using a single LDA threshold over a region encompassing a large portion of the NEUS failed to capture significant spatial differences in convective frequency and was substantially less accurate than using separate thresholds for smaller regions of the NEUS.

SST prediction methodologies and verification considerations for dynamical mid-summer rainfall forecasts for South Africa

Seasonal-to-interannual hindcasts (re-forecasts) for December-January-February (DJF) produced at a 1-month lead-time by the ECHAM4.5 atmospheric general circulation model (AGCM) are verified after calibrating model output to DJF rainfall at 94 districts across South Africa. The AGCM is forced with SST forecasts produced by (i) statistically predicted SSTs, and (ii) predicted SSTs from a dynamically coupled ocean-atmosphere model. The latter SST forecasts in turn consist of an ensemble mean of SST forecasts, and also by considering the individual ensemble members of the SST forecasts. Probabilistic hindcasts produced for two separate category thresholds are verified over a 24-year test period from 1978/79 to 2001/02 by investigating the various AGCM configurations’ attributes of discrimination (whether the forecasts are discernibly different given different outcomes) and reliability (whether the confidence communicated in the forecasts is appropriate). Deterministic hindcast skill is additionally calculated through a range of correlation estimates between hindcast and observed DJF rainfall. For both probabilistic and deterministic verification the hindcasts produced by forcing the AGCM with dynamically predicted SSTs attain higher skill levels than the AGCM forced with statistical SSTs. Moreover, ensemble mean SST forecasts lead to improved skill over forecasts that considered an ensemble distribution of SST forecasts.Keywords: AGCM, SST predictions, seasonal forecasting, South Africa