Publications by authors named "Nathan Kirk"

Discrepancy is a well-known measure for the irregularity of the distribution of a point set. Point sets with small discrepancy are called low discrepancy and are known to efficiently fill the space in a uniform manner. Low-discrepancy points play a central role in many problems in science and engineering, including numerical integration, computer vision, machine perception, computer graphics, machine learning, and simulation.

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Objectives: Characterize the dimensional spectrum of preadolescent (PA) irritability, a robust transdiagnostic vulnerability marker, using the youth version of the Multidimensional Assessment Profiles Temper Loss (MAPS-TL-Youth) scale including common and with developmentally specific items. Based on this, derive and validate a clinically optimized irritability screener to flag psychopathology risk in preadolescents.

Methods: The normal:abnormal irritability spectrum was modeled using MAPS-TL-Youth data from the Multidimensional Assessment of Preschoolers Study (MAPS) Study PA wave (n = 340) via item response theory.

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Objectives: Developmentally specified measures that identify clinically salient irritability are needed for early school-age youth to meaningfully capture this transdiagnostic risk factor for psychopathology. Thus, the current study modeled the normal:abnormal irritability spectrum and generated a clinically optimized screening tool for this population.

Methods: The irritability spectrum was modeled via the youth version of the Multidimensional Assessment Profile Scales-Temper Loss Scale (MAPS-TL-Youth) in children (n = 474; 6.

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Objectives: Heightened irritability in adolescence is an impairing symptom that can lead to negative outcomes in adulthood, but effective screening tools are lacking. This study aimed to derive clinically-optimized cutoff scores using the Multidimensional Assessment Profile Scales-Temper Loss (MAPS-TL) to pragmatically identify adolescents with impairing irritability.

Methods: A diverse sample of 79 adolescents and their parents completed the MAPS-TL-Youth version.

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Objectives: This study examines how accurate pediatric dentists are at estimating dental arch lengths by comparing their model estimations (guesstimating the arch length without measuring) to the Tanaka and Johnston mixed dentition arch length analysis.

Study Design: This study consisted of two parts, a survey of practitioners and a model estimating and measuring component. The survey was designed and given to 44 pediatric dentists to determine how many were practicing orthodontics and using arch length analyses routinely.

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Purpose: To investigate HIV transmission potential from a cluster of HIV infections among men who have sex with men to persons who inject drugs in 15 West Virginia counties. These counties were previously identified as highly vulnerable to rapid HIV dissemination through injection drug use (IDU) associated with high levels of opioid misuse.

Methods: We interviewed persons with 2017 HIV diagnoses about past-year risk behaviors and elicited sexual, IDU, and social contacts.

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Scleractinian corals occur in tropical regions near their upper thermal limits and are severely threatened by rising ocean temperatures. However, several recent studies have shown coral populations can harbour genetic variation in thermal tolerance. Here, we have extended these approaches to study heat tolerance of corals in the Persian/Arabian Gulf, where heat-tolerant local populations experience extreme summer temperatures (up to 36°C).

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Metabolic exchange between cnidarians and their symbiotic dinoflagellates is central to maintaining their mutualistic relationship. Sugars are translocated to the host, while ammonium and nitrate are utilized by the dinoflagellates (Symbiodinium spp.).

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Understanding the potential for coral adaptation to warming seas is complicated by interactions between symbiotic partners that define stress responses and the difficulties of tracking selection in natural populations. To overcome these challenges, we characterized the contribution of both animal host and symbiotic algae to thermal tolerance in corals that have already experienced considerable warming on par with end-of-century projections for most coral reefs. Thermal responses in Platygyra daedalea corals from the hot Persian Gulf where summer temperatures reach 36°C were compared with conspecifics from the milder Sea of Oman.

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Symbionts in each generation are transmitted to new host individuals either vertically (parent to offspring), horizontally (from exogenous sources), or a combination of both. Scleractinian corals make an excellent study system for understanding patterns of symbiont transmission since they harbor diverse symbionts and possess distinct reproductive modes of either internal brooding or external broadcast spawning that generally correlate with vertical or horizontal transmission, respectively. Here, we focused on the under-recognized, but apparently widespread, coral-associated apicomplexans (Protista: Alveolata) to determine if symbiont transmission depends on host reproductive mode.

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Numerous marine invertebrates form endosymbiotic relationships with dinoflagellates of the genus Symbiodinium, yet few studies have examined the population structure of these symbionts. Here, we elucidate the population genetic structure of Symbiodinium harboured by the Caribbean octocoral Gorgonia ventalina throughout the entire range of the host. We used ten microsatellite loci to survey 35 localities spanning 3124 km across the Caribbean and Western Atlantic.

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Here we report primers targeting 10 microsatellite loci of dinoflagellates in the genus Symbiodinium (clade B1/B184) symbiotic with the Caribbean sea fan coral, Gorgonia ventalina. Primers were tested on 12 Symbiodinium B1/B184 cultures, as well as 40 genomic DNA extracts of G. ventalina tissue samples.

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Like most Caribbean octocorals, Gorgonia ventalina, the common sea fan, harbors endosymbiotic dinoflagellates belonging to the genus Symbiodinium. When stressed, the host can lose these algal symbionts, a phenomenon termed "bleaching." Many cnidarians host multiple types of algal symbionts within the genus Symbiodinium, and certain types of algae may be more tolerant of stress than others.

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