Lower Threshold Level Research Articles

A robust smartphone based multi-channel dynamic-range audio compressor for hearing aids

Hearing impairment degrades perception of speech and audio signals due to low frequency-dependent audible threshold levels. Hearing aid devices (HADs) apply prescription gains and dynamic-range compressor for improving users’ audibility without increasing the sound loudness to uncomfortable levels. Multi-channel dynamic-range compressor enhances quality and intelligibility of audio output by targeting each frequency band with different compression parameters such as compression ratio (CR), attack time (AT), and release time (RT). Increasing the number of compressor channels can result in more comfortable audio output when appropriate parameters are defined for each channel. However, the use of more channels increases computational complexity of the multi-channel compressor algorithm limiting its application to some HADs. In this paper, we propose a nine-channel dynamic-range compressor with an optimized structure capable of running on smartphones and other portable digital platforms in real time. Test results showing the performance of proposed method are presented too.

Glutathione levels influence chronological life span of Saccharomyces cerevisiae in a glucose-dependent manner.

Diet plays a key role in determining the longevity of the organisms since it has been demonstrated that glucose restriction increases life span whereas a high-glucose diet decreases it. However, the molecular basis of how diet leads to the aging process is currently unknown. We propose that the quantity of glucose that fuels respiration influences reactive oxygen species generation and glutathione levels, and both chemical species impact in the aging process. Herein, we provide evidence that mutation of the gene GSH1 in Saccharomyces cerevisiae diminishes glutathione levels. Moreover, glutathione levels were higher with 0.5% than in 10% glucose in the gsh1Δ and wild-type strains. Interestingly, the chronological life span was lowered in the gsh1Δ strain cultured with 10% glucose but not under dietary restriction. The gsh1Δ strain also showed inhibition of the mitochondrial respiration in 0.5 and 10% glucose but only increased the H2 O2 levels under dietary restriction. These results correlate well with the GSH/GSSG ratio, which showed a decrease in gsh1Δ strain cultured with 0.5% glucose. Together, these data indicate that glutathione exhaustion impact negatively both the electron transport chain function and the chronological life span of yeast, the latter occurring when a low threshold level of this antioxidant is reached, independently of the H2 O2 levels.

Predicting reactivity threshold in children with anaphylaxis to peanut.

Peanut allergy necessitates dietary restrictions, preferably individualized by determining reactivity threshold through an oral food challenge (OFC). However, risk of systemic reactions often precludes OFC in children with severe peanut allergy. We aimed to determine whether clinical and/or immunological characteristics were associated with reactivity threshold in children with anaphylaxis to peanut and secondarily, to investigate whether these characteristics were associated with severity of the allergic reaction during OFC. A double-blinded placebo-controlled food challenge (DBPCFC) with peanut was performed in 96 5- to 15-year-old children with a history of severe allergic reactions to peanut and/or sensitization to peanut (skin prick test [SPT] ≥3 mm or specific immunoglobulin E [s-IgE] ≥0.35 kUA/L). Investigations preceding the DBPCFC included a structured interview, SPT, lung function measurements, serological immunology assessment (IgE, IgG and IgG4 ), basophil activation test (BAT) and conjunctival allergen provocation test (CAPT). International standards were used to define anaphylaxis and grade the allergic reaction during OFC. During DBPCFC, all 96 children (median age 9.3, range 5.1-15.2) reacted with anaphylaxis (moderate objective symptoms from at least two organ systems). Basophil activation (CD63+ basophils ≥15%), peanut SPT and the ratio of peanut s-IgE/total IgE were significantly associated with reactivity threshold and lowest observed adverse events level (LOAEL) (all P < .04). Basophil activation best predicted very low threshold level (<3 mg of peanut protein), with an optimal cut-off of 75.8% giving a 93.5% negative predictive value. None of the characteristics were significantly associated with the severity of allergic reaction. In children with anaphylaxis to peanut, basophil activation, peanut SPT and the ratio of peanut s-IgE/total IgE were associated with reactivity threshold and LOAEL, but not with allergy reaction severity.

Distributed Feedback Lasers Based on MAPbBr3

AbstractHybrid perovskite semiconductors hold great promise as low‐cost, yet high performance gain media for lasers. Distributed feedback (DFB) resonator structures are a key to unlock low laser threshold levels, which are essential on the way to the first electrically operated perovskite laser diode. Here, the first DFB lasers based on methylammonium lead bromide (MAPbBr3) thin films, with a linear photonic grating imprinted into the MAPbBr3 active layers is presented. High‐Q Bragg resonator gratings with a periodicity of 300 nm are directly patterned by thermal nanoimprinting into thin films of MAPbBr3 at a temperature as low as 100 °C. A notable effect of the imprinting process is a substantial flattening of the initially very rough polycrystalline perovskite layers to layers consisting of large crystals on the order of tens of microns with a surface roughness of 0.6 nm. The smooth surface affords a significantly lowered threshold for the onset of amplified spontaneous emission due to reduced scattering. In optically pumped DFB laser structures, very low lasing thresholds of 3.4 µJ cm−2 are achieved. It is foreseen that these results will influence research on perovskite‐based optoelectronic devices beyond lasers, e.g., light emitting diodes and solar cells.

It is not Black and White: Discrimination and distress in Hawai‘i.

This study investigates whether the strength of the relationship between perceived discrimination and psychological distress varies by race/ethnicity, gender, and the number of years of residence in Hawai'i. Our sample consisted of 1,036 undergraduate students at a university in Hawai'i and the survey was conducted in 2012-2013. The sample was composed of 55% women and the average age was 21. The students reported their racial/ethnic backgrounds as White (19%), Japanese (21%), Filipino (16%), Chinese (10%), Native Hawaiian (14%), Pacific Islander (4%), other Asian (6%), and other race/ethnicity (10%). Interaction effect results revealed that Whites who had experienced everyday discrimination had higher levels of psychological distress than racial ethnic minorities. Women who had experienced everyday discrimination were more distressed than men and more distressed by a lower threshold level of discrimination. Furthermore, those who had lived in Hawai'i for a longer duration and experienced everyday discrimination were more distressed. Our findings draw attention to how the psychological effects of discrimination vary by racial/ethnic group, gender, and location in the United States. The relationship between everyday discrimination and higher levels of psychological distress especially among those who have lived in Hawai'i longer, women, and Whites indicates that targeted medical and social interventions are needed to protect the mental health of college students. (PsycINFO Database Record

Vitamin D and Blood Pressure Among U.S. Adults: A Cross-sectional Examination by Race/Ethnicity and Gender

The cross-sectional association of serum vitamin D levels with blood pressure and hypertension status among a representative sample of U.S. adults was examined. Participants of the National Health and Nutrition Examination Survey from 2001 to 2010 were included in these analyses. Harmonizing of the vitamin D levels from 2001 to 2006 with vitamin D measurement from 2007 to 2010 was done using regression equations released by the Centers for Disease Control and Prevention. Use of vitamin D supplements was assessed for all participants. Statistical analyses included examination of linear association of vitamin D levels with blood pressure and non-linear cubic splines with hypertension in overall population, by gender, and by race/ethnicity. With every 10 nmol/L higher vitamin D, systolic blood pressure decreased by 0.19 mmHg in this population (p<0.01). In fully adjusted stratified analyses, this association was present among females (-0.25 mmHg, p<0.01) and non-Hispanic whites (0.22 mmHg, p<0.01). After race/ethnic and gender stratification, this association was observed among non-Hispanic white females (0.26 mmHg, p=0.01), non-Hispanic black females (0.65 mmHg, p=0.02), and marginally significant among Hispanic males (0.33 mmHg, p=0.07). Non-parametric assessment with cubic splines show that vitamin D has an inverse association with odds of hypertension up to 100 nmol/L with no apparent benefit at higher levels in overall population, and even lower threshold levels of vitamin D in non-Hispanic blacks (50 nmol/L) and Hispanic Americans (70 nmol/L). Significant race/ethnic and gender differences exist in the association of vitamin D and systolic blood pressure. Odds for hypertension are reduced significantly at higher vitamin D levels, but this benefit plateaus at very high vitamin D levels.

Second-Order Statistics of $\kappa-\mu$ Shadowed Fading Channels

In this paper, novel closed-form expressions for the level crossing rate and average fade duration of $\kappa-\mu$ shadowed fading channels are derived. The new equations provide the capability of modeling the correlation between the time derivative of the shadowed dominant and multipath components of the $\kappa-\mu$ shadowed fading envelope. Verification of the new equations is performed by reduction to a number of known special cases. It is shown that as the shadowing of the resultant dominant component decreases, the signal crosses lower threshold levels at a reduced rate. Furthermore, the impact of increasing correlation between the slope of the shadowed dominant and multipath components similarly acts to reduce crossings at lower signal levels. The new expressions for the second-order statistics are also compared with field measurements obtained for cellular device-to-device and body-centric communication channels, which are known to be susceptible to shadowed fading.

Characterization of the effectiveness of anti-scalants in suppressing scale deposition on a heated surface

A widely used technique for controlling scale deposition in desalination practice is by dosage of anti-scalants. Fundamental techniques for assessing the relative effectiveness of different anti-scalants are of considerable interest. The objective of the present research was to extend a technique characterizing the effectiveness of anti-scalants by identifying the threshold concentration at which scale deposition is unaffected by transport hydrodynamics and is purely surface controlled. A lower threshold level denotes higher inhibition effectiveness. The system investigated consisted of an electrically heated annular flow heat exchanger enabling measurement of calcium sulfate scale deposition on a stainless steel heating surface at a constant surface temperature. Application of the technique is illustrated by scale deposition measurements performed at varying Reynolds numbers in the absence and presence of three anti-scalants and at different scale deposition temperatures.

Determination of threshold concentrations of metals in indicator algae of coastal waters in the northwest Sea of Japan

Background concentrations of Fe, Mn, Cu, Zn, Pb, Cd, and Ni were calculated for thalli of abundant algae of Fucus, Silvetia, Sargassum, Cystoseira spp. from the northwest Sea of Japan during 1987–2008. As the upper threshold levels of metal background concentrations, the median values plus double medians of absolute deviations from the medians were used (Me + 2MAD). The lower threshold level of the background concentration equal to the physiological need for an element is the median of 15% minimum values in the sampling minus the double median of absolute deviations from the median (Me15–2MAD15). The range of Me15 ± 2MAD15 is considered the natural background range of concentrations.

Evaluation of a Modified HPGe Preamplifier for High-Rate Spectroscopy Measurements in a Pulsed Photonuclear Environment

Pulsed photonuclear techniques are commonly used in homeland security and nuclear safeguards applications to achieve enhanced detection sensitivity. For example, photoneutrons generated by a pulse-mode linear accelerator (linac) are commonly utilized to produce characteristic capture gamma rays for the detection of nitrogen-rich explosives. Recently, in an effort to develop innovative systems with increased sensitivity to detect diversion and prevent misuse, the authors proposed to assay used nuclear fuel for its plutonium content using a photofission technique, in support of nuclear material management in the U.S. fuel cycle.Passive spectroscopy measurements in the presence of intense background from fission products could be very difficult. Focusing on high-energy delayed gamma rays emitted by short-lived products from photofission presents a much more promising solution. However, as discovered in this study, a commercially available standard high-purity germanium (HPGe) preamplifier can be easily saturated for tens of milliseconds after each linac pulse. This greatly reduces the live time of the system especially when the linac repetition rate is high. On the other hand, although significantly reduced by increasing the lower-level threshold, the input count rate can still easily reach 106 cps (counts per second). Developing a gamma spectroscopy system that can handle such a high count rate has been a major challenge.In this work, a commercial HPGe preamplifier was modified to reduce the saturation time and tail time to improve its high-rate performance in a pulsed photonuclear environment. Results of the modifications were evaluated via both simulations and experiments and proven to be effective without significant degradation of energy resolution. The field-effect transistor (FET) and feedback components were first moved to the warm side to enable the modifications. The saturation time of the preamplifier following a linac pulse was greatly reduced by decreasing the value of the feedback resistor. The effect of reducing the tail time of the output signal was also studied. A traditional trapezoidal shaping approach was then employed to study the impact of the modifications on energy resolution.

The Current Treatment Situation and Definitions of a Cure for Chronic HBV Infection

HBV vaccination, while effective in reducing incident chronic disease in endemic regions, will not have the desired impact on the rates of end-stage liver disease in chronically infected persons. Over three decades, IFN-α and nucleoside analogs have reduced the morbidity from the disease. A large reservoir of chronic infection remains. The natural history of HBV infection is still being defined. Understanding the interactions between HBV and the host will be fundamental to achieving higher rates of cure. Curing hepatitis B will require several steps for either eradication, or a functional cure in the host. It is unclear whether covently closed circular DNA chromatin would need to be cleared to cure hepatitis B, or whether low threshold levels would slow the disease.

Allometric scaling, size distribution and pattern formation of natural cities

AbstractThere has been a strong interest in more cogent definitions on economies of scale to reveal general urban growth laws and to develop urban performance metrics. Unstructured data, including satellite images, will provide us with new sources to do so by defining cities as aggregates of human activities. Such a uniform definition on the basis of nighttime light clusters is more consistent and economically meaningful than administrative or official boundaries. In comparison with patterns of city systems found in traditional census data, we examined the allometric scaling, size distribution and fractal geometry of natural cities. It can be concluded from our empirical analysis on regional, country and continental scales that a super-linear scaling between lightness and area with a stable exponent across different low light threshold levels generally holds for natural cities. But Zipf’s Law does not always apply over the whole range of lightness thresholds. Furthermore, we build a model based on the simple geometric matching mechanism to reproduce the self-organized formation process of nighttime light patterns. The statistical properties including allometries, size distributions and fractal geometries generated by our model are in good agreement with empirical evidence. These findings have profound implications for understanding the effects of simple aggregation behaviour in primitive stages of city formation and the urbanization process.

오 경보 확률 감소를 위한 효율적인 임계치에 대한 연구

본 논문에서는 레이더 시스템에서 원하는 목표물 추정을 위한 효율적인 임계치 방법을 연구였다. 관심있는 목표물 탐지 검출 방법은 오 경보 확률을 변화 시켜 가면서 원하는 목표물을 추정한다. 이때 오 경보의 확률은 임계치와 밀접한 관계가 있다. 임계치를 낮게 하면 원하는 목표물의 정확도를 향상시킬 수 있지만 잡음 까지 추정하여 효율적인 신호처리 방법이 되지 못한다. 효율 적인 임계치 방법을 제안하여 원하는 목표물을 추정하는 연구 방법을 제안하다. 모의실험을 통해서 기존의 방법과 본 연구에서 제안한 방법을 비교 분석하였다. We have studied an efficient threshold level for desired target detection in radar system in the paper. A desired target searching detection method detects desired target according to changing for false alarm probability. This time, false alarm probability is close relation to threshold level. Low threshold level can improve detection for desired target, but detect noise signal. Therefor, This method is not good one. In this paper, we propose efficient threshold level method in order to estimation for desired target. Through simulation, we are analysis and performance to compare general method with proposal method. We show that proposed method is more good proof than general method.

Financial sector in resource-dependent economies

This paper examines financial sector characteristics in resource-dependent economies. Using an extensive data set covering 128 countries for the period 1995 to 2009, we present empirical evidence that the banking sector tends to be smaller in resource-dependent economies. Moreover, we locate a low threshold level at which the higher resource-dependence begins to be harmful for domestic banking sector. We also find evidence that the use of market-based financing is more common in resource-dependent economies. Further, our results suggest that a financial sector formed according to the needs of the resource sector might be unfavorable for emerging businesses, thereby hampering economic diversification and reinforcing the resource curse.

Combining experiments and modeling to characterize field driven phase transformations in relaxor ferroelectric single crystals

Field induced phase transformations in [011]C cut and poled relaxor ferroelectric single crystals can be induced by electrical or mechanical loading. Concurrent electrical and mechanical loading drives the ferroelectric rhombohedral to ferroelectric orthorhombic phase transformation at lower threshold levels than either load alone. The current experimental technique for characterization of the large field behavior including the phase transformation requires an extensive set of measurements performed under electric field cycling at different stress preloads and stress cycling at different bias electric fields repeated at multiple temperatures. Here, a mechanism based model is combined with a more limited set of experiments to obtain the same results. The model utilizes a work–energy criterion that calculates work required to induce the transformation by overcoming an energy barrier. In the relaxor single crystals, the energy barrier of phase transformations distributed over a range of field values is represented by a normal distribution of step like transformations. The results of the combined experiment/modeling approach are compared to the fully experimental approach and error is discussed.

Determination of multiple phytohormones in fruits by high-performance liquid chromatography with fluorescence detection using dispersive liquid-liquid microextraction followed by precolumn fluorescent labeling.

Plant hormone determination in food matrices has attracted more and more attention because of their potential risks to human health. However, analytical methods for the analysis of multiple plant hormones remain poorly investigated. In the present study, a convenient, selective, and ultrasensitive high-performance liquid chromatography method for the simultaneous determination of multiple classes of plant hormones has been developed successfully using dispersive liquid-liquid microextraction followed by precolumn fluorescent labeling. Eight plant hormones in fruits including jasmonic acid, 12-oxo-phytodienoic acid, indole-3-acetic acid, 3-indolybutyric acid, 3-indolepropionic acid, gibberellin A3 , 1-naphthylacetic acid, and 2-naphthaleneacetic acid were analyzed by this method. The conditions employed for dispersive liquid-liquid microextraction were optimized systematically. The linearity for all plant hormones was found to be >0.9993 (R(2) values). This method offered low detection limits of 0.19-0.44 ng/mL (at a signal-to-noise ratio of 3), and method accuracies were in the range of 92.32-103.10%. The proposed method was applied to determine plant hormones in five kinds of food samples, and this method can achieve a short analysis time, low threshold levels of detection, and a high specificity for the analysis of targeted plant hormones present at trace level concentrations in complex matrices.

Tactile sensitivity of vital and endodontically treated teeth

ObjectivesEndodontically treated teeth (ETT) used as abutments for removable partial dental prostheses (RPDPs) have an increased fracture risk as compared to vital abutments. One suggested explanation is that ETT exhibit a lower threshold level for tactile sensitivity than vital teeth. Therefore, this study compared the threshold for tactile sensitivity of vital teeth and ETT in the same individuals. MethodsForty participants with double crown-retained RPDPs fixed to vital teeth and ETT were included in the study. Each subject had at least one vital and one corresponding contralateral endodontically treated abutment tooth in the same jaw. After removal of the RPDP, an increasing centric force (0cN to max. 2000cN) was separately applied axially to both free-standing abutment teeth using a force gauge while the patient was asked to give three acoustic signals: (1) when noticing the first contact, (2) when noticing pressure and (3) when the pressure became displeasing. Afterwards, the same trial was performed with an eccentric force applied parallel to the tooth axis. ResultsStatistical analysis revealed no significant differences in the threshold of tactile sensitivity of vital teeth and ETT to either centric or eccentric loading (p>0.05). Eccentric loading showed lower mean threshold values compared to centric loading. A large variability of tactile sensitivity between individuals was noted. However, there were no gender-related significant differences in tactile sensitivity (p>0.05). ConclusionsThe tactile sensitivity of vital and non-vital teeth seems comparable. Clinical significanceThe assumption that a lower threshold level for tactile sensitivity in ETT than in vital teeth is responsible for their increased fracture risk could not be confirmed. Therefore, other reasons, e.g. loss of hard tissue due to root canal treatment, have to be considered responsible for the increased fracture risk of ETT.

Serum Concentrations of Hydroxybupropion for Dose Optimization of Depressed Patients Treated With Bupropion

Bupropion is a dopamine and norepinephrine reuptake inhibitor approved for the treatment of depression and smoking cessation. According to the recently published reviews, it is a candidate for therapeutic drug monitoring (TDM) to improve therapeutic outcomes and reduce risks of intolerability or intoxication. In practice, however, the use of TDM is limited due to the chemical instability of bupropion. This investigation sought to determine if the major, active, and chemically stable metabolite 4-hydroxybupropion is a suitable measure to guide antidepressant drug therapy with bupropion. 4-Hydroxybupropion serum levels were measured using a newly developed and validated high-performance liquid chromatography assay with ultraviolet detection. They correlated with therapeutic effects measured by the clinical global impression scale for improvement. The study included 52 patients (50% women). Patients who were markedly improved according to the clinical global impression scale score had significantly (P = 0.042) higher 4-hydroxybupropion serum levels than those with moderate or minimal improvement (mean ± SD, 1113 ± 576, 825 ± 398, and 475 ± 331 ng/mL, respectively). Analysis of receiver operating characteristics revealed significant predictive properties of 4-hydroxybupropion serum levels (P = 0.002) for marked improvement with a lower threshold level of 858 ng/mL. Under similar mean doses (265 ± 107 versus 239 ± 100 mg, respectively), women attained significantly higher serum levels than men (1050 ± 524 versus 589 ± 352 ng/mL, respectively) and exhibited a better therapeutic effect (P = 0.018). Despite multiple limitations of this naturalistic study, evidence could be given that the measurement of 4-hydroxybupropion in serum is suitable to perform TDM for bupropion. Blood levels should be above 860 ng/mL to attain therapeutic improvement. Potential sex differences in bupropion pharmacokinetics, probably due to differential activities of CYP2B6, should be taken into account when the drug is prescribed.

Prognostic importance of baseline and serial glycated hemoglobin levels in high-risk patients with type 2 diabetes: the Rio de Janeiro Type 2 Diabetes Cohort Study.

The prognostic importance of baseline and serial glycated hemoglobin (HbA1c) changes for cardiovascular outcomes is still debated. We aimed to evaluate it in 620 high-risk individuals with type 2 diabetes (mean age 60.4 years, 37 % males, 55 % Caucasians). Patients had HbA1c levels measured at study entry and serially during follow-up. Primary end points were total cardiovascular events (CVEs), major CVEs (non-fatal myocardial infarctions and strokes plus cardiovascular deaths) and all-cause mortality. Cardiovascular and non-cardiovascular mortalities were secondary end points. HbA1c was evaluated either as a continuous variable and categorized at clinically relevant cutoffs. Multivariate Cox regressions assessed the associations with end points. After a median follow-up of 6.6 years, 125 total CVEs occurred (90 major CVEs), and 111 patients died (64 from cardiovascular diseases). After statistical adjustments for other cardiovascular risk factors, baseline and mean first-year HbA1c predicted all end points, except non-cardiovascular deaths; and hazard ratios tended to be higher for mean first year than for baseline HbA1c. Each 1 % (10.9 mmol/mol) increase in mean first-year HbA1c increased 27 % the risk of major CVEs occurrence (95 % CI 11-45 %). Updating HbA1c for values obtained beyond the second year of follow-up did not improve its predictive performance. The cardiovascular protection was observed until HbA1c values lower than 6.5 % (48 mmol/mol). Moreover, the magnitude of HbA1c reduction during the first year of follow-up was predictive of better cardiovascular outcomes, independent of baseline HbA1c levels. In conclusion, better glycemic control, especially during the first year of follow-up, is determinant of better cardiovascular outcomes in high-risk patients with type 2 diabetes, without any detectable lower threshold level of HbA1c.

Quantification of Hepatic Steatosis: A Comparison of Computed Tomography and Magnetic Resonance Indices in Candidates for Living Liver Donation

To evaluate, in a group of candidates for liver donation, the role of unenhanced computed tomography (CT) and magnetic resonance (MR) as noninvasive means to measure hepatic steatosis (HS). Sixty-one consecutive candidates underwent CT and MR evaluation for liver donation within 3 weeks of liver biopsy. On CT, three methods of HS quantification were evaluated: the measurement of hepatic attenuation (CT L), the ratio of hepatic attenuation to splenic attenuation (CT L/S), and the difference between the hepatic and splenic attenuation (CT L-S). On MR, HS was reported in terms of fat signal fraction (FSF) using in-phase/opposed-phase and fat/non-fat- saturated images, with and without normalization with the spleen (T1W IP/OP FSF, T1W IP/OP FSF spleen and T2W ± FS FSF, TW2 ± FS FSF spleen). The accuracy of each imaging index in the diagnosis of HS, according to various thresholds, was assessed using receiver operating characteristic analysis. On biopsy, 35 donors showed no significant HS (<5%); the remaining 26 showed HS ranging from 5% to 40%. With all CT and MR indices, there was a trend toward increasing diagnostic accuracy as the threshold levels of HS increased. When comparing all the indices, TW2 ± FS FSF(spl) showed higher accuracy at threshold levels of 5% and 10% of steatosis but without reaching statistical significance. In candidates for living donation, MR and CT indices are similar in estimating liver-fat content; however, MR with T2W ± FS FSF(spl) sequences shows higher accuracy when low threshold levels of steatosis (≤5% and ≤10% HS) are selected.