A unified model of illusory and occluded contour interpolation

Models of contour interpolation have been proposed for illusory contour interpolation but seldom for interpolation of occluded contours. The identity hypothesis ( [Kellman and Loukides, 1987] and [Kellman and Shipley, 1991]) posits that an early interpolation mechanism is shared by interpolated contours that are ultimately perceived as either illusory or occluded. Here we propose a model of such a unified interpolation mechanism for illusory and occluded contours, building on the framework established in Heitger, von der Heydt, Peterhans, Rosenthaler, and Kubler (1998). We show that a single, neurally plausible mechanism that is consistent with the identity hypothesis also generates contour interpolations in agreement with perception for cases of transparency, self-splitting objects, interpolation with mixed boundary assignment, and “quasimodal” interpolations. Limiting cases for this local, feed-forward approach are presented, demonstrating that both early, local interpolation mechanisms and non-local scene constraints are necessary for describing the perception of interpolated contours.     

A community-based assessment of heat-related morbidity in North Philadelphia

A 6-month community-based study designed to (1) determine the perceptions and barriers affecting the overall quality of life of isolated older adults greater than 65 years of age, (2) assess their risk factors, health attitudes, and beliefs concerning their susceptibility to heat-related conditions, and (3) evaluate the effectiveness of an age-specific innovative intervention program consisting of a specially marked clock-like thermometer and other creative educational materials was conducted among 34 participants during the spring and summer of 1997 in north Philadelphia. The study objectives were measured at preintervention (baseline) and at 8 weeks postintervention follow-up using a 24-item pretest/posttest self-administered questionnaire. We report the short-term benefit of our intervention, theorize that innovative strategies targeting at-risk older adults should be culturally sensitive and age-specifically appropriate, and recommend that more vigorous research methods should be implemented to lend credence to our findings.     

MtDNA evidence for a genetic bottleneck in the early history of the Ashkenazi Jewish population

The relative roles of natural selection and accentuated genetic drift as explanations for the high frequency of more than 20 Ashkenazi Jewish disease alleles remain controversial. To test for the effects of a maternal bottleneck on the Ashkenazi Jewish population, we performed an extensive analysis of mitochondrial DNA (mtDNA) hypervariable segment 1 (HVS-1) sequence and restriction site polymorphisms in 565 Ashkenazi Jews from different parts of Europe. These patterns of variation were compared with those of five Near Eastern (n=327) and 10 host European (n=849) non-Jewish populations. Only four mtDNA haplogroups (Hgs) (defined on the basis of diagnostic coding region RFLPs and HVS-1 sequence variants) account for approximately 70% of Ashkenazi mtDNA variation. While several Ashkenazi Jewish mtDNA Hgs appear to derive from the Near East, there is also evidence for a low level of introgression from host European non-Jewish populations. HVS-1 sequence analysis revealed increased frequencies of Ashkenazi Jewish haplotypes that are rare or absent in other populations, and a reduced number of singletons in the Ashkenazi Jewish sample. These diversity patterns provide evidence for a prolonged period of low effective size in the history of the Ashkenazi population. The data best fit a model of an early bottleneck (approximately 100 generations ago), perhaps corresponding to initial migrations of ancestral Ashkenazim in the Near East or to Europe. A genetic bottleneck followed by the recent phenomenon of rapid population growth are likely to have produced the conditions that led to the high frequency of many genetic disease alleles in the Ashkenazi population.     

Living Donor Adult Liver Transplantation: A Longitudinal Study of the Donor''s Quality of Life

We report the results of a prospective, longitudinal quality of life survey on our adult right lobe (RL) liver donors. A total of 47 donors were enrolled; a standard SF-36 form and 43 questions developed by our team were completed before donation, at 1 week, and 1, 3, 6 and 12 months after donation. There were no donor deaths. Twenty-nine complications occurred in 16 patients. Major complication rate was 12.8%. Employment status and personal finances were identified as major stressors. All donors who wished to return to work did so by 1 year (mean 3.4 months). Individuals reported between 0 dollars and 25,000 dollars in losses (wages, travel, lodging, etc.). Relationships with recipients and other family members were not altered significantly. Anticipated pain (predonation) was greater than actual pain reported. Donors indicated satisfaction with the donation process regardless of recipient outcome. Physical complaints were significant at 1 week and 1 month, but returned to baseline. Donor mental health remained stable. In conclusion, RL donors found the experience to be a positive one throughout the first postdonation year. The study identified areas (finances, employment and expected recipient outcomes) to be stressed as future donors are evaluated.     

Improved Survival After Live Donor Adult Liver Transplantation (LDALT) Using Right Lobe Grafts: Program Experience and Lessons Learned

We present our program experience with 85 live donor adult liver transplantation (LDALT) procedures using right lobe grafts with five simultaneous live donor kidney transplants using different donors performed over a 6-year period. After an "early" 2-year experience of 25 LDALT procedures, program improvements in donor and recipient selection, preoperative imaging, donor and recipient surgical technique and immunosuppressive management significantly reduced operative mortality (16% vs. 3.3%, p = 0.038) and improved patient and graft 1-year survival in recipients during our "later" experience with the next 60 cases (January 2001 and March 2005; patient survival: early 70.8% vs. later 92.7%, p = 0.028; graft survival: Early 64% vs. later 91.1%, p = 0.019, respectively). Overall patient and graft survival were 82% and 80%. There was a trend for less postoperative complications (major and minor) with program experience (early 88% vs. later 66.7%; p = 0.054) but overall morbidity remained at 73.8%. Biliary complications (cholangitis, disruption, leak or stricture) were not influenced by program experience (early 32% vs. later 38%). Liver volume adjusted to 100% of standard liver volume (SLV) within 1 month post-transplant. Despite a high rate of morbidity after LDALT, excellent patient and graft survival can be achieved with program experience.     

Genome sequencing reveals complex speciation in the Drosophila simulans clade

The three species of the Drosophila simulans clade--the cosmopolitan species, D. simulans, and the two island endemic species, D. mauritiana and D. sechellia--are important models in speciation genetics, but some details of their phylogenetic and speciation history remain unresolved. The order and timing of speciation are disputed, and the existence, magnitude, and timing of gene flow among the three species remain unclear. Here we report on the analysis of a whole-genome four-species sequence alignment that includes all three D. simulans clade species as well as the D. melanogaster reference sequence. The alignment comprises novel, paired short-read sequence data from a single highly inbred line each from D. simulans, D. mauritiana, and D. sechellia. We are unable to reject a species phylogeny with a basal polytomy; the estimated age of the polytomy is 242,000 yr before the present. However, we also find that up to 4.6% of autosomal and 2.2% of X-linked regions have evolutionary histories consistent with recent gene flow between the mainland species (D. simulans) and the two island endemic species (D. mauritiana and D. sechellia). Our findings thus show that gene flow has occurred throughout the genomes of the D. simulans clade species despite considerable geographic, ecological, and intrinsic reproductive isolation. Last, our analysis of lineage-specific changes confirms that the D. sechellia genome has experienced a significant excess of slightly deleterious changes and a dearth of presumed favorable changes. The relatively reduced efficacy of natural selection in D. sechellia is consistent with its derived, persistently reduced historical effective population size.     

Use of a Combination Biomarker Algorithm To Identify Medical Intensive Care Unit Patients with Suspected Sepsis at Very Low Likelihood of Bacterial Infection

Sepsis remains a diagnostic challenge in the intensive care unit (ICU), and the use of biomarkers may help in differentiating bacterial sepsis from other causes of systemic inflammatory syndrome (SIRS). The goal of this study was to assess test characteristics of a number of biomarkers for identifying ICU patients with a very low likelihood of bacterial sepsis. A prospective cohort study was conducted in a medical ICU of a university hospital. Immunocompetent patients with presumed bacterial sepsis were consecutively enrolled from January 2012 to May 2013. Concentrations of nine biomarkers (α-2 macroglobulin, C-reactive protein [CRP], ferritin, fibrinogen, haptoglobin, procalcitonin [PCT], serum amyloid A, serum amyloid P, and tissue plasminogen activator) were determined at baseline and at 24 h, 48 h, and 72 h after enrollment. Performance characteristics were calculated for various combinations of biomarkers for discrimination of bacterial sepsis from other causes of SIRS. Seventy patients were included during the study period; 31 (44%) had bacterial sepsis, and 39 (56%) had other causes of SIRS. PCT and CRP values were significantly higher at all measured time points in patients with bacterial sepsis. A number of combinations of PCT and CRP, using various cutoff values and measurement time points, demonstrated high negative predictive values (81.1% to 85.7%) and specificities (63.2% to 79.5%) for diagnosing bacterial sepsis. Combinations of PCT and CRP demonstrated a high ability to discriminate bacterial sepsis from other causes of SIRS in medical ICU patients. Future studies should focus on the use of these algorithms to improve antibiotic use in the ICU setting.