Approximate Threshold Research Articles

A New Structure for Binary and Multiple Hyperspectral Change Detection Based on Spectral Unmixing and Convolutional Neural Network

The earth is constantly being changed by natural events and human activities that constantly threaten our environment. Therefore, accurate and timely monitoring of changes at the surface of the earth is of great importance for properly facing their consequences. This research presents a new hyperspectral change detection (HCD) framework based on a robust binary mask and convolutional neural network (CNN). The proposed method is implemented in three parts: (1) the first part provides a robust binary change map based on Otsu and dynamic time wrapping (DTW) algorithms; the DTW algorithm plays a predictor role that is a robust predictor for HCD purposes. Also, Otsu’s algorithm gives an estimate about the approximate threshold for detecting change and no-change class areas. These class areas will be used in the next steps. (2) The second part generates pseudo training data based on an image differencing (ID) algorithm and spectral unmixing (SU) manner for multiple change detection. This pseudo training data will be used for training the CNN model in the next step. (3) Finally, the multiple change map is generated by training the CNN network based on pseudo training data. The result of HCD maps is compared to other robust hyperspectral change detection methods by two real bi-temporal hyperspectral image datasets. The result of HCD in multiple change map shows the proposed method can have high performance compared to other HCD methods with an overall accuracy (OA) of more than 92% and Kappa coefficient (KC) of 0.77 and higher.

The effects of multiple-period promotions differing in frequency and depth on internal reference price

ABSTRACT Many marketers use sales promotions but excessive discounting can lower consumers’ internal reference prices. Scant research examines the implications of discounts and premiums varying in frequency and depth across multiple buying periods on period-by-period reference prices. In three studies, we find discounts with deep depth generate lower internal reference prices than those with shallow depth at high frequency. Then, we find frequency moderates depth, identifying approximate threshold levels of reference-price change. Finally, we find that premiums with the same value as discounts preserve internal reference price even if they are implemented with high frequency and deep depth.

Transitivity and approximate consistency threshold determination for reciprocal preference relations in group decision making

In a group decision-making process, contradictory pairwise comparisons may exist in individual preferences or the group preferences even though the consensus level is reached. To avoid such a contradictory phenomenon, this study presents an approximate transitivity-based consistency threshold for reciprocal preference relations to ensure the reliability of the ranking of alternatives with reciprocal preference relations in group decision making. The natural inconsistency or intransitivity of reciprocal preference relations is analyzed and verified by numerical experiments. Then, using the results of numerical experiments, approximate transitivity-based consistency thresholds are introduced based on the objectives of minimising the Type I error, Type II error and total error in statistics. Moreover, a transitivity checking process regarding individual reciprocal preference relations and group reciprocal preference relations is incorporated in the group decision-making process. A transitivity-checking integrated group decision-making model is given for application. An example about the station selection for high-speed railway line is provided to show the necessity of the approximate transitivity-based consistency threshold in checking the transitivity of reciprocal preference relations for group decision making.

OUTCOME-DRIVEN THRESHOLDS OF CENTRAL SYSTOLIC BLOOD PRESSURE AND CROSS-CLASSIFICATION OF SYSTOLIC HYPERTENSION AT CENTRAL AND BRACHIAL ARTERIES

Objective: We aimed to determine the outcome-driven thresholds for central systolic blood pressure (cSBP) based on the new ACC/AHA hypertension classification and to explore the characteristics and prognosis associated with central systolic hypertension (cSHT). Design and method: In 5580 participants enrolled from 9 populations (mean age 54.2 years; 54.1% women), cSBP was estimated tonometrically from the radial waveform (SphygmoCor, Atcor, Australia). We determined the thresholds for cSBP, resulting in 5-year cardiovascular risks similar to those associated with the 2017 ACC/AHA classification of brachial systolic blood pressure (bSBP). Statistical methods included analysis of covariance, the log-rank test and proportional hazards regression. Results: Over 4.1 years (median), 203 persons died (6.4 per 1000 person years) and 252 experienced a composite cardiovascular endpoint (8.2 per 1000 person-years). After rounding to the nearest 5 mm Hg, approximate thresholds for elevated cSBP and stages 1 and 2 and severe cSHT were 110, 120, 130 and 150 mm Hg, respectively. In 3659 untreated subjects, those with isolated cSHT (cSBP > = 120 mmHg, n = 137, 3.7%), compared to the participants with central (cSBP < 120 mmHg) and brachial (bSBP <130 mmHg) normotension (n = 1953, 53.4%), were older, more likely being female, had smaller height, slower heart rate and higher augmentation index. The opposite was true for isolated brachial hypertension (bSHT; bSBP > = 130 mmHg, n = 192, 5.3%). Among 1921 treated patients, the use of b-blockers was more frequent (50% vs. 36.2%, P = 0.027), whereas in isolated cSHT (n = 72, 3.8%) compared with controlled cSBP, RAAS inhibitors less often used (50% vs. 65.3%, P = 0.013). Among all participants, with brachial and central normotension as reference, the multivariable-adjusted hazard ratios (95% confidence interval) of the composite cardiovascular events were 1.29 (0.57–2.90; P = 0.54) for isolated bSHT, 2.30 (1.22–4.33; P = 0.01) for isolated cSHT, and 2.00 (1.39–2.88; P = 0.002) for concordant cSHT and bSHT. Conclusions: Outcome-driven thresholds of central systolic BP were approximately 10 mm Hg lower than their brachial counterparts. cSHT, either isolated (4%) or combined bSHT (90%), was characterised by greater systolic augmentation and was associated with higher cardiovascular risk.

Composition and distribution of fish environmental DNA in an Adirondack watershed.

BackgroundEnvironmental DNA (eDNA) surveys are appealing options for monitoring aquatic biodiversity. While factors affecting eDNA persistence, capture and amplification have been heavily studied, watershed-scale surveys of fish communities and our confidence in such need further exploration.MethodsWe characterized fish eDNA compositions using rapid, low-volume filtering with replicate and control samples scaled for a single Illumina MiSeq flow cell, using the mitochondrial 12S ribosomal RNA locus for taxonomic profiling. Our goals were to determine: (1) spatiotemporal variation in eDNA abundance, (2) the filtrate needed to achieve strong sequencing libraries, (3) the taxonomic resolution of 12S ribosomal sequences in the study environment, (4) the portion of the expected fish community detectable by 12S sequencing, (5) biases in species recovery, (6) correlations between eDNA compositions and catch per unit effort (CPUE) and (7) the extent that eDNA profiles reflect major watershed features. Our bioinformatic approach included (1) estimation of sequencing error from unambiguous mappings and simulation of taxonomic assignment error under various mapping criteria; (2) binning of species based on inferred assignment error rather than by taxonomic rank; and (3) visualization of mismatch distributions to facilitate discovery of distinct haplotypes attributed to the same reference. Our approach was implemented within the St. Regis River, NY, USA, which supports tribal and recreational fisheries and has been a target of restoration activities. We used a large record of St. Regis-specific observations to validate our assignments.ResultsWe found that 300 mL drawn through 25-mm cellulose nitrate filters yielded greater than 5 ng/µL DNA at most sites in summer, which was an approximate threshold for generating strong sequencing libraries in our hands. Using inferred sequence error rates, we binned 12S references for 110 species on a state checklist into 85 single-species bins and seven multispecies bins. Of 48 bins observed by capture survey in the St. Regis, we detected eDNA consistent with 40, with an additional four detections flagged as potential contaminants. Sixteen unobserved species detected by eDNA ranged from plausible to implausible based on distributional data, whereas six observed species had no 12S reference sequence. Summed log-ratio compositions of eDNA-detected taxa correlated with log(CPUE) (Pearson’s R = 0.655, P < 0.001). Shifts in eDNA composition of several taxa and a genotypic shift in channel catfish (Ictalurus punctatus) coincided with the Hogansburg Dam, NY, USA. In summary, a simple filtering apparatus operated by field crews without prior expertise gave useful summaries of eDNA composition with minimal evidence of field contamination. 12S sequencing achieved useful taxonomic resolution despite the short marker length, and data exploration with standard bioinformatic tools clarified taxonomic uncertainty and sources of error.

APPLICATION OF KEGGIN TYPE PHOSPHOTUNGSTOVANADIC HETEROPOLY ACID AS SENSITIVE MATERIAL FOR CARBON MONOXIDE SENSOR

The possibility of using Keggin-type wolframvanadium heteropoly acid with the formula H5[PW10V2O40] as a sensitive material for the development of thin-film resistometric sensors for carbon monoxide is considered. In order to test the applicability of the selected heteropoly acid to solve the problem, thin films were obtained from an aqueous solution of the above-mentioned heteropoly acid by irrigation. Heteropolyacid films were formed on a dielectric citall substrate with metal interpenetrating nickel electrodes. To determine the sensitivity of a film consisting of heteropolyacid to carbon monoxide gas, a change in the electrical resistance of the film was recorded depending on the concentration of carbon monoxide in the air. An approximate alarm threshold was determined when the concentration of carbon monoxide approaches the maximum permissible concentration of the working zone, which is 20 mg/m3, in order to assess the possibility of developing signaling devices based on resistometric sensors, where the selected heteropoly acid can be used as a sensitive reagent. The conditions of interaction of carbon monoxide with the selected heteropoly acid are determined. These conditions consist in activation of a sensitive film consisting of heteropoly acid by ultraviolet radiation in the wavelength range from 230 to 290 nm. The proposed mechanism of interaction of heteropolyacid with carbon monoxide is considered and an explanation of the change in the number of charge carriers in a film consisting of heteropolyacid is proposed. The principal possibility of using a Keggin-type heteropoly acid with the formula H5[PW10V2O40] as a sensitive material for creating resistometric sensors for carbon monoxide without using catalytically active elements based on platinum, palladium or rare scattered elements is proved.

A Depth-Dependent Local Magnitude Scale for New Zealand Earthquakes Consistent with Moment Magnitude

ABSTRACTA new reference attenuation model for calculating local magnitude (ML) for New Zealand earthquakes is derived. An earlier reference model, denoted NZ16, was developed in 2016 as a possible alternative to the classical reference model used by GeoNet for earthquakes located by the SeisComP processing system since January 2012. It aimed to provide a logA0 attenuation relation of the amplitude with the hypocentral distance applicable to the New Zealand region and to make ML more consistent with moment magnitude (Mw). For the present update, denoted NZ20, a much larger set of regional moment tensor solutions and corresponding station amplitudes is available. Residual analysis is used to screen the individual station amplitude readings and then to exclude observations from periods of time when the station residuals were consistently anomalous. Effects of other possible sources of bias on the attenuation relation are also examined, including unreliable locations of earthquakes with large azimuthal gaps and the saturation of ML in large earthquakes. An extra explanatory variable is added to the attenuation relation to account for dependence on hypocentral depth, so the updated local magnitude is consistent with Mw across the full range of depths at which earthquakes occur in New Zealand. Furthermore, to counteract possible sources of bias, the data set for analysis is restricted. Earthquakes above the approximate amplitude saturation threshold of Mw 6.6, as well as those with azimuthal gaps greater than 270°, are excluded.

Variations in the Presence of Carotid Intraplaque Hemorrhage Across Age Categories: What Age Groups Are Most Likely to Benefit From Plaque Imaging?

Although carotid artery intraplaque hemorrhage (IPH) is a known risk-factor for cerebral ischemic events in patients of advanced age, its prevalence in younger cohorts is less certain. The purpose of this study was to assess the prevalence of carotid artery IPH across the age spectrum. A retrospective review was completed of all adult patients from our institution who underwent neck MRA with high-resolution carotid plaque imaging between 2017 and 2020. The mean ages of patients with and without IPH were calculated. The prevalence of IPH was compared between patients that were categorized into age groups. Patients with and without a cerebral ischemic event (e.g., stroke, retinal ischemia) were included. Unilateral anterior circulation ischemic events in patients without atrial fibrillation were presumed to be likely related to ipsilateral carotid artery disease. Multiple regression analysis was performed to determine independent associations with IPH. 634 patients were included (1,268 carotid arteries). Increasing age (OR: 1.04; 95% CI: 1.02–1.06; P = 0.001) was independently associated with IPH. 211 patients had unilateral anterior circulation ischemic events. The mean age of patients with carotid IPH was 71.4 years (SD = 9.9), compared to 62.8 years (SD = 15.8) of those without (P ≤ 0.0001). The prevalence of IPH increased with age in all patients (P = 0.0002). Among patients with ipsilateral anterior circulation ischemic events, each age category above 50 years had a significantly higher prevalence of IPH when compared to patients 18–50 years (P ≤ 0.05 for all comparisons). The prevalence of carotid IPH increases with age and is rare in patients under 50 years. The approximate threshold age for IPH development is likely around 50 years.

Comparison of Pure-Tone Thresholds and Cochlear Microphonics Thresholds in Pediatric Cochlear Implant Patients.

In adult cochlear implant patients, conventional audiometry is used to measure postoperative residual hearing which requires active listening and patient feedback. However, audiological measurements in pediatric cochlear implant patients are both challenging as well as time consuming. Intracochlear electrocochleography (ECOG) offers an objective and a time-efficient method to measure frequency-specific cochlear microphonic or difference thresholds (CM/DIF) thresholds that closely approximate auditory thresholds in adult cochlear implant patients. The correlation between CM/DIF and behavioral thresholds has not been established in pediatric cochlear implant patients. In the present study, CM/DIF thresholds were compared with audiometric thresholds in pediatric cochlear implant patients with postoperative residual hearing. Thirteen (11 unilateral and 2 bilateral) pediatric cochlear implant patients (mean age = 9.2 years ± 5.1) participated in this study. Audiometric thresholds were estimated using conventional, condition play, or visual reinforcement audiometry. A warble tone stimulus was used to measure audiometric thresholds at 125, 250, 500, 1000, and 2000 Hz. ECOG waveforms were elicited using 50-msec acoustic tone-bursts. The most apical intracochlear electrode was used as the recording electrode with an extra-cochlear ground electrode. The ECOG waveforms were analyzed to determine CM/DIF thresholds that were compared with pediatric cochlear implant patients' audiometric thresholds. The results show a significant correlation (r = 0.77, p < 0.01) between audiometric and CM/DIF thresholds over a frequency range of 125 to 2000 Hz in pediatric cochlear implant patients. Frequency-specific comparisons revealed a correlation of 0.82, 0.74, 0.69, 0.41, and 0.32 between the audiometric thresholds and CM/DIF thresholds measured at 125, 250, 500, 1000, and 2000 Hz, respectively. An average difference of 0.4 dB (±14 dB) was measured between the audiometric and CM/DIF thresholds. Intracochlear ECOG can be used to measure CM/DIF thresholds in pediatric cochlear implant patients with residual hearing in the implanted ear. The CM/DIF thresholds are similar to the audiometric thresholds at lower test frequencies and offer an objective method to monitor residual hearing in difficult-to-test pediatric cochlear implant patients.

Approximate Logic Synthesis: A Survey

Approximate computing is an emerging paradigm that, by relaxing the requirement for full accuracy, offers benefits in terms of design area and power consumption. This paradigm is particularly attractive in applications where the underlying computation has inherent resilience to small errors. Such applications are abundant in many domains, including machine learning, computer vision, and signal processing. In circuit design, a major challenge is the capability to synthesize the approximate circuits automatically without manually relying on the expertise of designers. In this work, we review methods devised to synthesize approximate circuits, given their exact functionality and an approximability threshold. We summarize strategies for evaluating the error that circuit simplification can induce on the output, which guides synthesis techniques in choosing the circuit transformations that lead to the largest benefit for a given amount of induced error. We then review circuit simplification methods that operate at the gate or Boolean level, including those that leverage classical Boolean synthesis techniques to realize the approximations. We also summarize strategies that take high-level descriptions, such as C or behavioral Verilog, and synthesize approximate circuits from these descriptions.

Feature selection in deterministic policy gradient

The authors consider the task of learning control problem in reinforcement learning (RL) with continuous action space. Policy gradient, and in particular the determinist policy gradient (DPG) algorithm, provides a method for solving learning control problem with continuous action space. However, when the RL task is complex enough so that tuning of the function approximation is necessary, hand-tuning for the features is infeasible. In order to solve this problem, the authors extend DPG algorithm by adding an approximate-linear-dependency-based sparsification procedure, which makes DPG algorithm to automatically select the useful and sparse features. As far as the authors know, this is the first time to consider the feature selection problem in DPG. Simulation results illustrate that (i) the proposed algorithm can find the optimal solution of the continuous version of mountain car problem; (ii) the proposed algorithm achieves good performance over a large range of the approximate linear dependency threshold parameter settings.

A hybrid phase boundary detection technique for two-phase-flow PIV measurements

Particle Image Velocimetry (PIV) measurement accuracy is lower along the phase boundaries of two-phase-flows, because the interrogation windows contain information from both phases. Different seeding density, background intensity, velocity magnitude and flow direction conditions often exist across the boundary, and the cross-correlation-based PIV algorithm selects only the highest correlation peak. The highest correlation peak is either influenced by the wrong phase (across the boundary), or the correctly calculated displacement is erroneously detected as an outlier at a later stage and is subsequently replaced. Phase-separated PIV measurements minimize this problem, and increase accuracy along the boundary by treating each phase separately. This type of measurement requires for each time step; (i) the accurate detection of the phase boundary in consecutive frames, (ii) generation of dynamic phase masks, (iii) an accurate PIV evaluation of each phase and (iv) recombination of the flow fields. In this article, we focus on the first step and test a hybrid phase boundary detection (PBD) technique in three different two-phase-flow configurations which manifest different challenges: The first configuration is the mixing of two liquids in a magnetic micromixer, the second is a combustion experiment where a turbulent, pre-mixed, low-swirl, lifted flame is investigated, and the third is a bubble column reactor where air bubbles are rising in a water tank. The PBD implementation uses a three-step procedure: approximate global thresholding, local Otsu thresholding, and discrimination of image gradients. Comparison of results with and without the use of PBD and phase separation indicate that there are significant measurement accuracy improvements along the boundary.

On a Possible Logarithmic Connection between Einstein’s Constant and the Fine-Structure Constant, in Relation to a Zero-energy Hypothesis

This paper brings into attention a possible logarithmic connection between Einstein’s constant and the fine-structure constant, based on a hypothetical electro-gravitational resistivity of vacuum: we also propose a zero-energy hypothesis (ZEH) which is essentially a conservation principle applied on zero-energy that mainly states a general quadratic equation having a pair of conjugate mass solutions for each set of coefficients, thus predicting a new type of mass “symmetry” called here “mass conjugation” between elementary particles (EPs) which predicts the zero/non-zero rest masses of all known/unknown EPs to be conjugated in boson-fermion pairs; ZEH proposes a general formula for all the rest masses of all EPs from Standard model, also indicating a possible bijective connection between the three types of neutrinos and the massless bosons (photon, gluon and the hypothetical graviton), between the electron/positron and the W boson and predicting two distinct types of neutral massless fermions (modelled as conjugates of the Higgs boson and Z boson respectively) which are plausible candidates for dark energy and dark matter. ZEH also offers a new interpretation of Planck length as the approximate length threshold above which the rest masses of all known elementary particles have real number values (with mass units) instead of complex/imaginary number values (as predicted by the unique quadratic equation proposed by ZEH).

Loop seals in circulating fluidized beds – Review and parametric studies using CPFD simulation

Loop seal is a robust particle recycling technique used in circulating fluidized bed (CFB) reactors. The rate and the location of the loop seal aeration exert a significant impact on the rate of particle circulation (GS). The standpipe balances the cumulative pressure drop across the rest of the CFB by adjusting its particle height or gas-particle slip velocity. Higher fraction of the loop seal aeration naturally flows down to riser. Increased pressure drop in the standpipe results in high rate of particle circulation.Computational-particle-fluid-dynamic (CPFD) code is customized for multiphase flow modelling. The inbuilt tool of “BC connectors” was incorporated to downsize a CFB into a loop seal. The simulation results of GS and system pressures for loop seal showed a perfect match with experimentally validated CFB model. A parametric study for the effects of aeration rate, aeration position and length of the horizontal section was performed using the developed CPFD model of the loop seal. GS increased proportionally with the loop seal aeration, reaching an approximate threshold at 0.9 Nm3/h and beyond that GS did not improve significantly. Uniform aeration from the loop seal bottom realized the highest particle circulation with a 71% increment. The length of the horizontal section of the loop seal exhibited an inverse relationship on the particle circulation.

Plant community type is an indicator of the seasonal moisture deficit in a disturbed raised bog

AbstractDepth to water table is a simple, commonly used measure of hydrological function in raised bogs. The maximum depth of the water table or the average annual water table is often monitored over the long term to track the hydrological trajectory of the ecosystem. These measures, however, may not take into account the duration of the moisture deficit period. The annual water table moisture deficit (WTMD) at 67 sites in a single disturbed raised bog was calculated using the amount of time that the water table was at each depth below the surface during the moisture deficit season. The calculated value estimates a linearly developing deficit that dewaters the acrotelm during the moisture deficit season. At each site, plant species composition was assigned to one of eight plant community types. The approximate threshold above which bog plant communities will begin transitioning into drier types with taller shrubs and trees was a WTMD of 62 m‐days. An annual climatic moisture deficit (CMD) was calculated using daily air temperature, spatially interpolated precipitation and estimated potential evapotranspiration for each site. Mixed‐effects modelling of WTMD as a function CMD indicated a positive linear relation for most vegetation types, which was affected by the presence of drainage ditches, ditch blocking, fire and evapotranspiration by shrubs and trees. Tracking the WTMD and its relation to CMD may be useful for assessing ecosystem health and serve as a basis for estimating moisture deficit thresholds for bogs of conservation concern.

Optimal iterative threshold-kernel estimation of jump diffusion processes

In this paper, we propose a new threshold-kernel jump-detection method for jump-diffusion processes, which iteratively applies thresholding and kernel methods in an approximately optimal way to achieve improved finite-sample performance. As in Figueroa-López and Nisen (Stoch Process Appl 123(7):2648–2677, 2013), we use the expected number of jump misclassifications as the objective function to optimally select the threshold parameter of the jump detection scheme. We prove that the objective function is quasi-convex and obtain a new second-order infill approximation of the optimal threshold in closed form. The approximate optimal threshold depends not only on the spot volatility \(\sigma _t\), but also the jump intensity and the value of the jump density at the origin. Estimation methods for these quantities are then developed, where the spot volatility is estimated by a kernel estimator with thresholding and the value of the jump density at the origin is estimated by a density kernel estimator applied to those increments deemed to contain jumps by the chosen thresholding criterion. Due to the interdependency between the model parameters and the approximate optimal estimators built to estimate them, a type of iterative fixed-point algorithm is developed to implement them. Simulation studies for a prototypical stochastic volatility model show that it is not only feasible to implement the higher-order local optimal threshold scheme but also that this is superior to those based only on the first order approximation and/or on average values of the parameters over the estimation time period.

Investigating the Relation between Level of Service and Volume-to-Capacity ratio at Signalized Intersections under Heterogeneous Traffic Condition

Among the various performance measures for assessing the operational condition of signalized intersection, both volume-to-capacity (v/c) ratio and control delay have gained importance universally. Even though delay is used as the service measure for arriving at the level of service (LOS) of signalized intersection, the practitioners use v/c ratio as the prime indicator of intersection performance. This study aims at understanding the significance of using the v/c ratio as an indicator of signalized intersection performance under Indian context. Previous studies and various highway capacity manuals have proposed a one-to-one relationship between delay and v/c ratio. The relationship has been revisited to find out whether there is a one-to-one correspondence. Further, an attempt was made to investigate the relationship between level of service and the v/c ratio at signalized intersection under heterogeneous traffic condition. The delay model proposed in the Indian Highway Capacity Manual (Indo-HCM) has been used for this. The results show that the delay distribution under different degrees of saturation are overlapping and it is difficult to arrive at v/c thresholds for each LOS category. i.e. there is no one-to-one correspondence between v/c ratio and delay values. Based on the study results, some approximate thresholds of v/c ratios are proposed for LOS of signalized intersections under heterogeneous traffic condition.

Nontrivial path covers of graphs: existence, minimization and maximization

Let G be a graph and $${{{\mathcal {P}}}}$$ be a set of pairwise vertex-disjoint paths in G. We say that $${{\mathcal {P}}}$$ is a path cover if every vertex of G belongs to a path in $${{\mathcal {P}}}$$. In the minimum path cover problem, one wishes to find a path cover of minimum cardinality. In this problem, known to be $${\textsc {NP}}$$-hard, the set $${{\mathcal {P}}}$$ may contain trivial (single-vertex) paths. We study the problem of finding a path cover composed only of nontrivial paths. First, we show that the corresponding existence problem can be reduced to a matching problem. This reduction gives, in polynomial time, a certificate for both the yes-answer and the no-answer. When trivial paths are forbidden, for the feasible instances, one may consider either minimizing or maximizing the number of paths in the cover. We show that, the minimization problem on feasible instances is computationally equivalent to the minimum path cover problem: their optimum values coincide and they have the same approximation threshold. We show that the maximization problem can be solved in polynomial time. We also consider a weighted version of the path cover problem, in which we seek a path cover with minimum or maximum total weight (the number of paths do not matter), and we show that while the first is polynomial, the second is NP-hard, but admits a constant-factor approximation algorithm. We also describe a linear-time algorithm on (weighted) trees, and mention results for graphs with bounded treewidth.

Climate change, interspecific competition, and poleward vs. depth distribution shifts: Spatial analyses of the eastern Bering Sea snow and Tanner crab (Chionoecetes opilio and C. bairdi)

Snow crab (Chionoecetes opilio), an arctic species, and Tanner crab (C. bairdi), a subarctic species, support large-scale industrial fisheries in the eastern Bering Sea and are spatially overlapping congeneric species at the opposite boundaries of their distributional ranges in the eastern North Pacific. Using summer bottom trawl survey data from 1982 to 2017, spatial analyses and geostatistical regressions were conducted for each species for three population categories (immature females, oldshell mature females, and oldshell large males) to explore intra and interspecies differences in habitat and spatial distributions as well as interspecific spatial co-occurrence patterns. Variability in depth distributions rather than poleward distributional shifts may be a Tanner crab response to ocean warming, the apparent converse of snow crab. Both temperature and depth have strong effects on the Tanner crab distributions and 2 °C is an approximate minimum temperature threshold for Tanner crab habitat. 2 °C is an important maximum temperature threshold for immature female snow crab but temperature effects are weaker for adult snow crab. Snow crab ontogenetic movement results in loose coupling between settlement and adult habitat and in significant spatial overlap between older snow crab and Tanner crab. The similarity in spatial distributions and habitat of older snow crab with juvenile Tanner crab habitat and the predatory nature of snow suggest a possible regulatory role of snow crab on the northern extent of spatial distributions of Tanner crab, along with other possible factors such as groundfish predation. Snow crab distributions will most probably continue to shift northwards with warming ocean temperatures but a poleward shift for Tanner crab appears more uncertain. The utilities of comparing spatial and non-spatial models and accounting for spatial confounding in spatial regression modeling are also addressed.

Impact of Temporal Lobe Epilepsy on Central Auditory Processing in Children

Background: Anatomical and functional integrity of the auditory pathways, from peripheral to central structures, is essential for proper processing of auditory stimuli and a satisfactory development of language, speech, and learning. Neurological disorders, such as epilepsy, are one of the possible causes of central auditory disorders. Objective: The aim of the current work was to study the effect of temporal lobe epilepsy on auditory temporal resolution ability in children. Patients and methods: Thirty children suffering from temporal lobe epilepsy, with age ranged from 12 to 16 years, were included in this study. Also, 10 apparently healthy children with age and gender matched with the study group were taken as a control group. All children were subjected to full history taking, clinical examination, cognitive and basic audiological evaluation. Also, questionnaire for central auditory processing disorders in children was applied and assessment of temporal resolution ability using Gaps In Noise (GIN) test. Results: Children with temporal lobe epilepsy had significantly increased gap detection threshold (GDTh) values, and lower percentage of correct gap detection than control group. 86.7% of epileptic children demonstrated abnormal scores for approximate GIN threshold (gap detection threshold above 6 msec, with sensitivity and specificity of 80% and 100% for right ear and 86% and 100% for left ear. Conclusion: Temporal resolution deficit is a comorbidity in children with temporal lobe epilepsy and is increased with longer duration of epilepsy. Impairment was not affected by age, gender, medications or duration of treatment. Also, there was no significant difference between both ears in GIN test, reflecting no laterality effect.