Exceptional preservation of mid-Cretaceous marine arthropods and the evolution of novel forms via heterochrony.

Evolutionary origins of novel forms are often obscure because early and transitional fossils tend to be rare, poorly preserved, or lack proper phylogenetic contexts. We describe a new, exceptionally preserved enigmatic crab from the mid-Cretaceous of Colombia and the United States, whose completeness illuminates the early disparity of the group and the origins of novel forms. Its large and unprotected compound eyes, small fusiform body, and leg-like mouthparts suggest larval trait retention into adulthood via heterochronic development (pedomorphosis), while its large oar-like legs represent the earliest known adaptations in crabs for active swimming. Our phylogenetic analyses, including representatives of all major lineages of fossil and extant crabs, challenge conventional views of their evolution by revealing multiple convergent losses of a typical "crab-like" body plan since the Early Cretaceous. These parallel morphological transformations may be associated with repeated invasions of novel environments, including the pelagic/necto-benthic zone in this pedomorphic chimera crab.

Interference enhanced thermoelectricity in quinoid type structures.

Quantum interference (QI) effects in molecular junctions may be used to obtain large thermoelectric responses. We study the electrical conductance G and the thermoelectric response of a series of molecules featuring a quinoid core using density functional theory, as well as a semi-empirical interacting model Hamiltonian describing the π-system of the molecule which we treat in the GW approximation. Molecules with a quinoid type structure are shown to have two distinct destructive QI features close to the frontier orbital energies. These manifest themselves as two dips in the transmission, that remain separated, even when either electron donating or withdrawing side groups are added. We find that the position of the dips in the transmission and the frontier molecular levels can be chemically controlled by varying the electron donating or withdrawing character of the side groups as well as the conjugation length inside the molecule. This feature results in a very high thermoelectric power factor S(2)G and figure of merit ZT, where S is the Seebeck coefficient, making quinoid type molecules potential candidates for efficient thermoelectric devices.

Electronic structure calculations with GPAW: a real-space implementation of the projector augmented-wave method.

Electronic structure calculations have become an indispensable tool in many areas of materials science and quantum chemistry. Even though the Kohn-Sham formulation of the density-functional theory (DFT) simplifies the many-body problem significantly, one is still confronted with several numerical challenges. In this article we present the projector augmented-wave (PAW) method as implemented in the GPAW program package (https://wiki.fysik.dtu.dk/gpaw) using a uniform real-space grid representation of the electronic wavefunctions. Compared to more traditional plane wave or localized basis set approaches, real-space grids offer several advantages, most notably good computational scalability and systematic convergence properties. However, as a unique feature GPAW also facilitates a localized atomic-orbital basis set in addition to the grid. The efficient atomic basis set is complementary to the more accurate grid, and the possibility to seamlessly switch between the two representations provides great flexibility. While DFT allows one to study ground state properties, time-dependent density-functional theory (TDDFT) provides access to the excited states. We have implemented the two common formulations of TDDFT, namely the linear-response and the time propagation schemes. Electron transport calculations under finite-bias conditions can be performed with GPAW using non-equilibrium Green functions and the localized basis set. In addition to the basic features of the real-space PAW method, we also describe the implementation of selected exchange-correlation functionals, parallelization schemes, ΔSCF-method, x-ray absorption spectra, and maximally localized Wannier orbitals.

Benchmark density functional theory calculations for nanoscale conductance.

We present a set of benchmark calculations for the Kohn-Sham elastic transmission function of five representative single-molecule junctions. The transmission functions are calculated using two different density functional theory methods, namely an ultrasoft pseudopotential plane-wave code in combination with maximally localized Wannier functions and the norm-conserving pseudopotential code SIESTA which applies an atomic orbital basis set. All calculations have been converged with respect to the supercell size and the number of k|| points in the surface plane. For all systems we find that the SIESTA transmission functions converge toward the plane-wave result as the SIESTA basis is enlarged. Overall, we find that an atomic basis with double zeta and polarization is sufficient (and in some cases, even necessary) to ensure quantitative agreement with the plane-wave calculation. We observe a systematic downshift of the SIESTA transmission functions relative to the plane-wave results. The effect diminishes as the atomic orbital basis is enlarged; however, the convergence can be rather slow.

Outcome of formocresol/ZOE sub-base pulpotomies utilizing alternative radiographic success criteria.

PURPOSE: The purposes of this investigation were to 1) measure success of a primary tooth pulpotomy technique that applies formocresol in the sub-base without the common five-minute application of a formocresol impregnated cotton pellet; and 2) compare success rates of the pulpotomy procedure using traditional criteria found throughout the literature with new criteria recently established, excluding internal resorption as a radiographic failure. METHODS: Clinical and radiographic data were collected from a retrospective chart review of patients receiving formocresol pulpotomies with the application of formocresol in the zinc oxide-eugenol sub-base. RESULTS: Clinical and radiographic data were available for 196 primary molars in 122 children (followup=six to 103 months; mean=49 months). Traditional assessment of radiographic success and failure yielded a success rate of 79%. Alternative assessment excluding internal resorption as a failure yielded a 99% success rate. Most frequently observed pulpal responses were calcific metamorphosis and internal resorption. Overall clinical success was 99%. Two of the 196 teeth were extracted due to failure. A survival analysis demonstrated that the overall probability of survival remained high over time with a cumulative survival of over 95% after six years. CONCLUSIONS: The overall success rates in this study indicate that the formocresol pulpotomy technique incorporating formocresol in the zinc oxide-eugenol sub-base is a very successful treatment modality for primary molars requiring pulp therapy.

Leukocyte and endothelial cell adhesion molecules in a chronic murine model of myocardial reperfusion injury.

Expression of endothelial and leukocyte cell adhesion molecules is a principal determinant of polymorphonuclear neutrophil (PMN) recruitment during inflammation. It has been demonstrated that pharmacological inhibition of these molecules can attenuate PMN influx and subsequent tissue injury. We determined the temporal expression of alpha-granule membrane protein-40 (P-selectin), endothelial leukocyte adhesion molecule 1 (E-selectin), and intercellular cell adhesion molecule 1 (ICAM-1) after coronary artery occlusion and up to 3 days of reperfusion. The expression of all of these cell adhesion molecules peaked around 24 h of reperfusion. We determined the extent to which these molecules contribute to PMN infiltration by utilizing mice deficient (-/-) in P-selectin, E-selectin, ICAM-1, and CD18. Each group underwent 30 min of in vivo, regional, left anterior descending (LAD) coronary artery ischemia and 24 h of reperfusion. PMN accumulation in the ischemic-reperfused (I/R) zone was assessed using histological techniques. Deficiencies of P-selectin, E-selectin, ICAM-1, or CD18 resulted in significant (P < 0.05) attenuation of PMN infiltration into the I/R myocardium (MI/R). In addition, P-selectin, E-selectin, ICAM-1, and CD18 -/- mice exhibited significantly (P < 0.05) smaller areas of necrosis after MI/R compared with wild-type mice. These data demonstrate that MI/R induces coronary vascular expression of P-selectin, E-selectin, and ICAM-1 in mice. Furthermore, genetic deficiency of P-selectin, E-selectin, ICAM-1, or CD18 attenuates PMN sequestration and myocardial injury after in vivo MI/R. We conclude that P-selectin, E-selectin, ICAM-1, and CD18 are involved in the pathogenesis of MI/R injury in mice.

Valuation effects of health cost containment measures.

This study reports the findings of research into the valuation effects of health cost containment activities by publicly traded corporations. The motivation for this study was employers' increasing cost of providing health care insurance to their employees and employers' efforts to contain those costs. A 1990 survey of corporate health benefits indicated that these costs represented 25 percent of employers' net earnings and this would rise by the year 2000 if no actions were taken to reduce cost. Health cost containment programs that are implemented by firms should be seen by shareholders as a wealth maximizing effort. As such, this should be reflected in share price. This study employed standard event study methodology where the event is a media announcement or report regarding an attempt by a firm to contain the costs of providing health insurance and other health related benefits to employees. It examined abnormal returns on a number of event days and for a number of event intervals. Of the daily and interval returns that are least significant at the 10 percent level, virtually all are negative. Cross-sectional analysis shows that the abnormal returns are related negatively to a unionization variable.

Bilateral versus unilateral mandibular block anesthesia in a pediatric population.

PURPOSE: This prospective study aimed to evaluate unilateral versus bilateral mandibular nerve block anesthesia with regard to post-operative soft tissue trauma and other complications in a pediatric population. METHODS: A total of 320 patients age 2 to 18 years were appointed for routine operative treatment. There were no age, gender, behavior, or general health exclusions. Oral and written post-operative instructions were given to parents, as well as a survey preview. A phone survey was conducted after treatment to determine a number of variables, including soft tissue trauma. RESULTS: A total of 13% of all patients experienced post-operative soft tissue trauma. By age group, trauma frequency was 18% (< 4 yrs.), 16% (4-7 yrs.), 13% (8-11 yrs.) and 7% (> 12 yrs.). Comparing unilateral versus bilateral subjects as to trauma revealed that in the < 4 age group trauma was higher for the unilateral subjects (35% vs. 5%, P < .02). Non-significant trends showed increased trauma in unilateral groups at ages 8-11 and > 12 years. CONCLUSION: This study represents the first documentation of post-anesthetic soft tissue trauma prevalence in a pediatric population. The results reveal no contraindication to the use of bilateral mandibular block anesthesia.

Sonography of the circumrenal and horseshoe adrenal gland in the newborn.

The adrenal gland can be visualized using ultrasonography in at least 90% of fetuses of more than 26 weeks gestation. The fetal and neonatal adrenal gland is described as a structure having a characteristic V or Y shape. Despite the frequency of visualization of the neonatal adrenal gland, few reports of adrenal anomalies are present in the radiologic literature. The purpose of this paper is to describe and depict the sonographic appearance of the "horseshoe" and the "circumrenal" adrenal gland and to discuss adrenal anomalies in general.

Malrotation in twins: a rare occurrence.

Although malrotation is commonly found in infants with intestinal obstruction, the presence of malrotation in twins is rare. We report a set of twins who each had malrotation and non-bilious vomiting on the first day of life.

Serving two masters: the interaction between Family and Medical Leave Acts and the ADA.

The complex interaction between family leave acts and the new Americans with Disabilities Act (ADA) is just coming to light as employers begin to analyze how to comply with both laws. Specifically, the ADA implicates the procedures set forth in most family leave acts for verifying an employee's need for a leave through mandatory medical examinations and doctor's certificates. Many employees who are entitled to a leave of absence under state law are defined as "disabled" under the ADA. The ADA protects these employees with disabilities by regulating medical examinations and inquiries, and protecting the confidentiality of information obtained in such inquiries. This article offers some practical guidance for employers in providing leaves of absence under state family leave acts, while verifying the need for leaves in compliance with the ADA.

Mycoplasmal infections of cerebrospinal fluid in newborn infants from a community hospital population.

Mycoplasma hominis or Ureaplasma urealyticum have previously been isolated from cerebrospinal fluid (CSF) in 13 of 100 newborn infants tested from a high risk university hospital population where the mothers were of predominantly lower income and socioeconomic status and had often received little or no prenatal care. We sought to determine whether such infections occur in neonates born to women cared for mainly through private obstetric practices and who delivered in 4 suburban community hospitals. CSF cultures were done in 318 infants during an 8-month period. M. hominis was isolated from 9 and U. urealyticum from 5 CSF cultures. Four infants infected with U. urealyticum and 3 infected with M. hominis were born at term. One infant infected with U. urealyticum had a birth weight of less than 1000 g. In 5 infants clearance of the infecting organism was documented without specific treatment. Twelve infants had good perinatal outcomes regardless of treatment and 2 died. One death in a 2240-g infant infected with M. hominis was associated with Haemophilus influenzae sepsis and pneumonia. The other death occurred 3 days after birth in a 630-g infant infected with U. urealyticum who had evidence of meningitis and intraventricular hemorrhage. Results of this study suggest that mycoplasmas are common causes of neonatal CSF infections, not only in high risk populations, but also in the general population.

A randomized, controlled trial of very early prophylactic ligation of the ductus arteriosus in babies who weighed 1000 g or less at birth.

We speculated that prophylactic ligation of the ductus arteriosus would reduce mortality and morbidity in very-low-birth-weight infants. To test this hypothesis, we randomly assigned 84 babies who weighed 1000 g or less at birth and required supplemental oxygen either to receive standard treatment (n = 44) or to undergo prophylactic surgical ligation of the ductus arteriosus on the day of birth (n = 40). The ductus was ligated in babies in the control group only if the shunt was hemodynamically important. All the babies were followed for one year. The incidence of necrotizing enterocolitis was reduced in the group that underwent prophylactic ligation (3 of 40 [8 percent]) as compared with the control group (13 of 44 [30 percent]; P = 0.002). The frequency of death, bronchopulmonary dysplasia, retinopathy of prematurity, and intraventricular hemorrhage was similar in both groups. Because early enteral feeding may have increased the incidence of necrotizing enterocolitis, we analyzed separately the babies who were fed early. Among the infants who were fed within 14 days of birth, those who underwent prophylactic ligation had a lower incidence of necrotizing enterocolitis (1 of 11 [9 percent]) than those who did not (13 of 24 [54 percent]; P = 0.001). Within the control group, the infants who were fed within 14 days of birth and whose ductus was ligated for medical reasons within 5 days of birth had a lower incidence of necrotizing enterocolitis (2 of 10 [20 percent]) than those whose ductus was ligated later or not at all (11 of 14 [79 percent]; P = 0.004). We conclude that early surgical closure of the ductus arteriosus reduces the risk of necrotizing enterocolitis in infants of very low birth weight who require supplemental oxygen.

Defining the family in family medicine: implications for social workers.

Physicians and social workers in the family medicine setting anticipate that a substantial portion of their practice will consist of intact, nuclear families. This study examined that expectation by collecting data on age, sex, and marital status of the patients in a family practice residency. Two separate methods of sampling the practice were used, and each resulted in a different picture of the practice. A dramatic finding was that 9% of the patients with active medical charts consumed 45% of the medical care. Women and patients over age 40 were overrepresented in the sample of frequent-user patients. Social work implications are presented.

Neonatal transcutaneous bilirubinometry.

The authors present data supporting the conclusion that the transcutaneous bilirubin index may be a valuable tool to help distinguish term babies with a total serum bilirubin value less than 13 mg/dl from those with higher levels and that it serves as a valuable screening device to decrease the number of unnecessary total serum bilirubin tests. Also examined are clinical guidelines and limitations of the device.

Trypanosoma brucei: detection of low parasitaemias in mice by a miniature anion-exchanger/centrifugation technique.

A method is described for the detection of trypanosomaemia in mice using the samples of about 55 microliter of blood which can be readily obtained from mice by puncture of the retro-orbital plexus with heparinized glass microhaematocrit tubes. The samples, mixed with an appropriate diluent, are passed through small (2 ml) anion-exchanger columns by means of peristatic pumps and the eluates collected in tubes which can be centrifuged so as to concentrate any organisms in the terminal part of the tube, of calibre about 200 micrometer, for microscopical examination. Evidence is presented to show that the method is more sensitive than other methods in use. It is also quick, requiring only some five minutes per mouse examined.

Filter wedge spectrometer for field use.

Two spectrometers, utilizing interference filter wedges, have been constructed for measurements under field conditions. One, operating from 1.6 micro. to 5.4 micro, has been flown unpressurized in an airplane to 12.2 km; the other, operating from 7.4 micro to 14.6 micro has been flown in a balloon to 33.3 km. Both instruments performed well, proving the interference filter wedge as avaluable tool for spectral measurements, especially in hostile environments.