Optimizing Pulsar Timing Arrays to Maximize Gravitational Wave Single Source Detection: a First Cut

Pulsar Timing Arrays (PTAs) use high accuracy timing of a collection of low timing noise pulsars to search for gravitational waves in the microhertz to nanohertz frequency band. The sensitivity of such a PTA depends on (a) the direction of the gravitational wave source, (b) the timing accuracy of the pulsars in the array and (c) how the available observing time is allocated among those pulsars. Here, we present a simple way to calculate the sensitivity of the PTA as a function of direction of a single GW source, based only on the location and root-mean-square residual of the pulsars in the array. We use this calculation to suggest future strategies for the current North American Nanohertz Observatory for Gravitational Waves (NANOGrav) PTA in its goal of detecting single GW sources. We also investigate the affects of an additional pulsar on the array sensitivity, with the goal of suggesting where PTA pulsar searches might be best directed. We demonstrate that, in the case of single GW sources, if we are interested in maximizing the volume of space to which PTAs are sensitive, there exists a slight advantage to finding a new pulsar near where the array is already most sensitive. Further, the study suggests that more observing time should be dedicated to the already low noise pulsars in order to have the greatest positive effect on the PTA sensitivity. We have made a web-based sensitivity mapping tool available at http://gwastro.psu.edu/ptasm.Comment: 14 pages, 3 figures, accepted by Ap

Prevalence of Deep Periodontal Pockets in New Mexico Adults Aged 27 to 74 Years *

The purpose of this study was to describe the distribution of advanced periodontal destruction (pocket depth equal to or deeper than six mm) in continuous residents, aged 27 to 74 years, of Lordsburg and Deming, New Mexico. The distance from the free gingival margin to the base of the gingival crevice or pocket was measured on the facial and mesiofacial sides of six index teeth. The presence of supragingival calculus, subgingival calculus, and plaque, as well as gingival bleeding around the index teeth, also were evaluated. Of the 372 examinees, only 46 individuals (12.4 percent) had at least one deep pocket equal to or deeper than six mm on at least one site on the six index teeth. Age was significantly associated with prevalence of deep pockets, although about 80 percent of those aged 47 to 74 years did not have deep pockets. Of those with deep pockets, 89.1 percent had fewer than four tooth sites (out of 12) affected. The only significant risk factor of the presence of deep pockets, other than age, was the number of teeth with plaque accumulations. Age and the number of teeth with plaque explained only 10.5 percent of the variability in the prevalence of deep pocketing, suggesting that risk factors other than those included in this study may be important. The results of this study indicate that destructive periodontal disease occurs at selected sites within the mouth, and that about 87 percent of the adults over age 27, in this population, do not have deep pockets in the si. index teeth examined.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66049/1/j.1752-7325.1986.tb03142.x.pd

Glycemic Control and Alveolar Bone Loss Progression in Type 2 Diabetes

This study tested the hypothesis that the risk for alveolar bone loss is greater, and bone loss progression more severe, for subjects with poorly controlled (PC) type 2 diabetes mellitus (type 2 DM) compared to those without type 2 DM or with better controlled (BC) type 2 DM. The PC group had glycosylated hemoglobin (HbA1) ≥ 9%; the BC group had HbA1 < 9%. Data from the longitudinal study of the oral health of residents of the Gila River Indian Community were analyzed. Of the 359 subjects, aged 15 to 57 with less than 25% radiographic bone loss at baseline, 338 did not have type 2 DM, 14 were BC, and 7 were PC. Panoramic radiographs were used to assess interproximal bone level. Bone scores (scale 0–4) corresponding to bone loss of 0%, 1% to 24%, 25% to 49%, 50% to 74%, or ≥ 75% were used to identify the worst bone score (WBS) in the dentition. Change in worst bone score at follow‐up, the outcome, was specified on a 4‐category ordinal scale as no change, or a 1‐, 2‐, 3‐, or 4‐category increase over baseline WBS (WBS1). Poorly controlled diabetes, age, calculus, time to follow‐up examination, and WBS1 were statistically significant explanatory variables in ordinal logistic regression models. Poorly controlled type 2 DM was positively associated with greater risk for a change in bone score (compared to subjects without type 2 DM) when the covariates were included in the model. The cumulative odds ratio (COR) at each threshold of the ordered response was 11.4 (95% CI = 2.5, 53.3). When contrasted with subjects with BC type 2 DM, the COR for those in the PC group was 5.3 (95% CI = 0.8, 53.3). The COR for subjects with BC type 2 DM was 2.2 (95% CI = 0.7, 6.5), when contrasted to those without type 2 DM. These results suggest that poorer glycemic control leads to both an increased risk for alveolar bone loss and more severe progression over those without type 2 DM, and that there may be a gradient, with the risk for bone loss progression for those with better controlled type 2 DM intermediate to the other 2 groups. Ann Periodontol 1998;3:30–39.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142262/1/aape0030.pd

The Mission Accessible Near-Earth Objects Survey: Four years of photometry

Over 4.5 years, the Mission Accessible Near-Earth Object Survey (MANOS) assembled 228 Near-Earth Object (NEO) lightcurves. We report rotational lightcurves for 82 NEOs, constraints on amplitudes and periods for 21 NEOs, lightcurves with no detected variability within the image signal to noise and length of our observing block for 30 NEOs, and 10 tumblers. We uncovered 2 ultra-rapid rotators with periods below 20s; 2016MA with a potential rotational periodicity of 18.4s, and 2017QG$_{18}$ rotating in 11.9s, and estimate the fraction of fast/ultra-rapid rotators undetected in our project plus the percentage of NEOs with a moderate/long periodicity undetectable during our typical observing blocks. We summarize the findings of a simple model of synthetic NEOs to infer the object morphologies distribution using the measured distribution of lightcurve amplitudes. This model suggests a uniform distribution of axis ratio can reproduce the observed sample. This suggests that the quantity of spherical NEOs (e.g., Bennu) is almost equivalent to the quantity of highly elongated objects (e.g., Itokawa), a result that can be directly tested thanks to shape models from Doppler delay radar imaging analysis. Finally, we fully characterized 2 NEOs as appropriate targets for a potential robotic/human mission: 2013YS$_{2}$ and 2014FA$_{7}$ due to their moderate spin periods and low $\Delta v$.Comment: Accepted for Publication, The Astrophysical Journal Supplement Serie

Advances in the Epidemiological Study of Oral-Facial Diseases

Both demographic patterns and disease distribution are changing rapidly in the United States. These developments have led to the recognition that the epidemiology of many conditions is poorly understood, and that other research has thus been hindered. Four areas of epidemiological study were chosen for detailed analysis of how new technology will affect the conduct of future research. These areas, selected because information about them will be increasingly needed in an aging society, were periodontitis, temporomandibular disorders (TMD) and other orofacial pain, salivary gland disturbances, and health services research. The potential effect of new technology was examined in the short, intermediate, and long term. While the nature of epidemiological study is unlikely to change with the advent of new technology, the scope of potential studies will become broader. Advances in diagnostic techniques from elsewhere will permit far more precise diagnosis than is possible at present. Computer technology will permit an efficient system of epidemiological surveillance to provide current data on trends in tooth loss, caries, and periodontitis—data which will complement the results of national surveys. Analytical studies to produce hypotheses on the etiology of oral conditions, especially in such poorly-understood areas as chronic pain and TMD, will help direct clinical research in those areas.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66664/2/10.1177_08959374890030010301.pd

Prenatal exposure to metal mixtures and newborn neurobehavior in the Rhode Island Child Health Study

Background: Prenatal exposure to metals can affect the developing fetus and negatively impact neurobehavior. The associations between individual metals and neurodevelopment have been examined, but little work has explored the potentially detrimental neurodevelopmental outcomes associated with the combined impact of coexisting metals. The objective of this study is to evaluate prenatal metal exposure mixtures in the placenta to elucidate the link between their combined effects on newborn neurobehavior. Method: This study included 192 infants with available placental metal and NICU Network Neurobehavioral Scale data at 24 hours-72 hours age. Eight essential and nonessential metals (cadmium, cobalt, copper, iron, manganese, molybdenum, selenium, zinc) detected in more than 80% of samples were tested for associations with atypical neurobehavior indicated by NICU Network Neurobehavioral Scale using logistic regression and in a quantile g-computation analysis to evaluate the joint association between placental metal mixture and neurobehavioral profiles. Results: Individually, a doubling of placental cadmium concentrations was associated with an increased likelihood of being in the atypical neurobehavioral profile (OR = 2.39; 95% CI = 1.05 to 5.71). In the mixture analysis, joint effects of a quartile increase in exposure to all metals was associated with 3-fold increased odds of newborns being assigned to the atypical profile (OR = 3.23; 95% CI = 0.92 to 11.36), with cadmium having the largest weight in the mixture effect. Conclusions: Prenatal exposure to relatively low levels of a mixture of placental metals was associated with adverse newborn neurobehavior. Examining prenatal metal exposures as a mixture is important for understanding the harmful effects of concomitant exposures in the vulnerable populations

Non‐Insulin Dependent Diabetes Mellitus and Alveolar Bone Loss Progression Over 2 Years

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141702/1/jper0076.pd