A kilonova as the electromagnetic counterpart to a gravitational-wave source.

Gravitational waves were discovered with the detection of binary black-hole mergers and they should also be detectable from lower-mass neutron-star mergers. These are predicted to eject material rich in heavy radioactive isotopes that can power an electromagnetic signal. This signal is luminous at optical and infrared wavelengths and is called a kilonova. The gravitational-wave source GW170817 arose from a binary neutron-star merger in the nearby Universe with a relatively well confined sky position and distance estimate. Here we report observations and physical modelling of a rapidly fading electromagnetic transient in the galaxy NGC 4993, which is spatially coincident with GW170817 and with a weak, short γ-ray burst. The transient has physical parameters that broadly match the theoretical predictions of blue kilonovae from neutron-star mergers. The emitted electromagnetic radiation can be explained with an ejected mass of 0.04 ± 0.01 solar masses, with an opacity of less than 0.5 square centimetres per gram, at a velocity of 0.2 ± 0.1 times light speed. The power source is constrained to have a power-law slope of -1.2 ± 0.3, consistent with radioactive powering from r-process nuclides. (The r-process is a series of neutron capture reactions that synthesise many of the elements heavier than iron.) We identify line features in the spectra that are consistent with light r-process elements (atomic masses of 90-140). As it fades, the transient rapidly becomes red, and a higher-opacity, lanthanide-rich ejecta component may contribute to the emission. This indicates that neutron-star mergers produce gravitational waves and radioactively powered kilonovae, and are a nucleosynthetic source of the r-process elements.

Super-cooled and amorphous lipid-based colloidal dispersions for the delivery of phytosterols.

Super-cooled and amorphous lipid-based colloids are highly desirable delivery systems because of their ability to encapsulate compounds in a soluble or in a non-crystalline state. In this study, we demonstrate the preparation and characterization of super-cooled and amorphous lipid-based nanoscale colloidal dispersions containing high concentrations of phytosterols (PSs). PSs are highly hydrophobic natural bioactive compounds that are known to significantly reduce blood cholesterol levels in humans, but are insoluble in water and are poorly soluble in common lipids such as triacylglycerols (TAGs). Using the ultrahigh pressure homogenization of pre-heated dispersions, followed by temperature quenching, colloidal dispersions with varying concentrations of PSs in the lipid phase are prepared. Long and medium chain TAGs in combination with a non-ionic surfactant are used. The particle size, morphology and stability are analysed by dynamic and static light scattering, electron microscopy, and X-ray diffraction. Rapid temperature quenching enables the formation of stable colloidal dispersions of 10 wt% PSs, more than five times the equilibrium solubility at room temperature. Super-cooled emulsions are formed using liquid TAG, whereas amorphous particles are formed in the case of solid TAG. In both cases, the complete suppression of the crystallization of both PSs and lipids is observed due to the nanoscale confinement. The colloidal dispersions are stable for at least four months. The insights of this work will help understand the colloid formation and particle morphology control in the development of delivery systems for hydrophobic bio-actives such as drugs, cosmeceuticals, nutraceuticals, nutritional and agricultural nanoscale formulations.

Osmotic stress and the yeast cytoskeleton: phenotype-specific suppression of an actin mutation.

In the yeast Saccharomyces cerevisiae, actin filaments function to direct cell growth to the emerging bud. Yeast has a single essential actin gene, ACT1. Diploid cells containing a single copy of ACT1 are osmosensitive (Osms), i.e., they fail to grow in high osmolarity media (D. Shortle, unpublished observations cited by Novick, P., and D. Botstein. 1985. Cell. 40:415-426). This phenotype suggests that an underlying physiological process involving actin is osmosensitive. Here, we demonstrate that this physiological process is a rapid and reversible change in actin filament organization in cells exposed to osmotic stress. Filamentous actin was stained using rhodamine phalloidin. Increasing external osmolarity caused a rapid loss of actin filament cables, followed by a slower redistribution of cortical actin filament patches. In the recovery phase, cables and patches were restored to their original levels and locations. Strains containing an act1-1 mutation are both Osms and temperature-sensitive (Ts) (Novick and Botstein, 1985). To identify genes whose products functionally interact with actin in cellular responses to osmotic stress, we have isolated extragenic suppressors which revert only the Osms but not the Ts phenotype of an act1-1 mutant. These suppressors identify three genes, RAH1-RAH3. Morphological and genetic properties of a dominant suppressor mutation suggest that the product of the wild-type allele, RAH3+, is an actin-binding protein that interacts with actin to allow reassembly of the cytoskeleton following osmotic stress.

A Method for Investigating "Instructional Familiarity" and Discerning Authentic Learning.

BACKGROUND: Presently, most medical educators rely exclusively on item difficulty and discrimination indices to investigate an item's psychometric quality and functioning. We argue "instructional familiarity" effects should also be of primary concern for persons attempting to discern the quality and meaning of a set of test scores. AIM: There were four primary objectives of this study: (1) Revisit Haladyna and Roid's conceptualization of "instructional sensitivity" within the context of criterion-referenced assessments, (2) provide an overview of "instructional familiarity" and its importance, (3) reframe the concept for a modern audience concerned with medical school assessments, and (4) conduct an empirical evaluation of a medical school examination in which we attempt to investigate the instructional effects on person and item measures. SUBJECTS AND METHODS: This study involved a medical school course instructor providing ratings of instructional familiarity (IF) for each mid-term examination item, and a series of psychometric analyses to investigate the effects of IF on students' scores and item statistics. The methodology used in this study is based primarily on a mixed-method, "action research" design for a medical school course focusing on endocrinology. Rasch measurement model; correlation analysis. RESULTS: The methodology presented in this article was evidenced to better discern authentic learning than traditional approaches that ignore valuable contextual information about students' familiarity with exam items. CONCLUSIONS: The authors encourage other medical educators to adopt this straightforward methodology so as to increase the likelihood of making valid inferences about learning.

Reliability and physiologic correlates of the Harvard Alumni Activity Survey in a general population.

The reliability of the Harvard Alumni Activity Survey (HAAS) and its association with physiologic measures was assessed in a large sample of men and women aged 25-65 years residing in the Boston metropolitan area in 1987. Reliability was estimated by comparing HAAS energy expenditure reports (kcal/week) from two separate interviews conducted 7-12 weeks apart. The test-retest reliability coefficient was 0.58 for the entire sample, but was considerably higher (r = 0.69) for those whose activity patterns had not changed from one interview to the next. HAAS self-reports were compared to two physiologic measures known to be affected by physical activity: high density lipoprotein cholesterol (HDLC) and body mass index (BMI). The natural logarithm of weekly HAAS expenditures was positively correlated with HDLC (r = 0.14, p less than 0.01) and negatively correlated with BMI (r = 0.13, p less than 0.01) for all respondents. These statistically significant associations persisted when adjusted for other covariates influencing physiologic status. The reliability coefficients and physiologic correlations for the HAAS in this sample are comparable to those reported for physical activity instruments requiring more intensive data collection and scoring procedures.

The Physical Activity Scale for the Elderly (PASE): development and evaluation.

A Physical Activity Scale for the Elderly (PASE) was evaluated in a sample of community-dwelling, older adults. Respondents were randomly assigned to complete the PASE by mail or telephone before or after a home visit assessment. Item weights for the PASE were derived by regressing a physical activity principal component score on responses to the PASE. The component score was based on 3-day motion sensor counts, a 3-day physical activity dairy and a global activity self-assessment. Test-retest reliability, assessed over a 3-7 week interval, was 0.75 (95% CI = 0.69-0.80). Reliability for mail administration (r = 0.84) was higher than for telephone administration (r = 0.68). Construct validity was established by correlating PASE scores with health status and physiologic measures. As hypothesized, PASE scores were positively associated with grip strength (r = 0.37), static balance (r = +0.33), leg strength (r = 0.25) and negatively correlated with resting heart rate (r = -0.13), age (r = -0.34) and perceived health status (r = -0.34); and overall Sickness Impact Profile score (r = -0.42). The PASE is a brief, easily scored, reliable and valid instrument for the assessment of physical activity in epidemiologic studies of older people.

Local excision of carcinoma of the rectum for cure.

During the past 10 years, we have treated 63 patients with invasive adenocarcinoma of the rectum by full-thickness local excision. Rigid criteria were employed in patient selection. None of the tumors was pedunculated or in situ carcinoma. Of the 63 lesions, 53 were confined to the bowel wall and constitute the basis for this report. Thirty-five lesions penetrated only the submucosa and 18 invaded the muscularis propria. Twenty-four patients underwent full-dose postoperative radiotherapy with minimal complications. Follow-up ranged from 12 to 130 months, with a median of 44 months. Four tumors recurred locally (8%). Of these, two patients apparently have been salvaged by reexcision. One patient died 32 months after abdominoperineal resection of brain metastases (without local tumor). One patient who did not receive close follow-up died of local recurrence. Seven have died of unrelated causes. The 5-year corrected disease-free survival is 90%. Local excision combined with radiotherapy for selected rectal cancers yields a high rate of cure with minimal morbidity and is now our preferred mode of treatment for all patients whose tumors meet our rigid criteria.

Antibiotic prophylaxis during clean neurosurgery: a large, multicenter study using cefuroxime.

Cefuroxime is a second-generation cephalosporin with in vitro activity against the organisms that are commonly associated with neurosurgical wound infections. Other properties of cefuroxime are an elimination half-life of 1.3 hours, which yields prolonged serum concentrations, and its ability to penetrate the blood-brain barrier in proportion to the degree of inflammation. A prospective, multicenter, open-label study was conducted to evaluate the efficacy and safety of cefuroxime for antibiotic prophylaxis in patients undergoing clean neurosurgery. Cefuroxime 1.5 g was given intravenously 25 to 60 minutes before surgery; for procedures lasting more than 3 hours, cefuroxime 750 mg was given intravenously 8 hours after the initial dose. Patients were examined before surgery, daily during hospitalization, and at 8 weeks after surgery. A total of 956 adults were enrolled in the study. The most common procedures in study patients were laminectomy (41.8% of patients) or craniotomy (24.3%), and the mean duration of surgery was 3.2 hours. Infection occurred in 2 (0.3%) of 592 assessable patients by the time of discharge and in 1 additional patient by the 8-week follow-up evaluation for a total of 3 (0.5%) of 560 assessable patients. Drug-related adverse events occurred in 5 (0.5%) of 956 patients. These results indicate that antibiotic prophylaxis with cefuroxime is associated with a low incidence of postoperative wound infection and is well tolerated in patients undergoing clean neurosurgery.

Is cardiovascular risk factor knowledge sufficient to influence behavior?

This paper examines the level of cardiovascular risk knowledge in the general population and the relationship between such knowledge and behavior. The following questions are addressed: (1) How informed is the general population about what persons can do to reduce their risk of cardiovascular disease? (2) How do sociodemographic factors, self-perceptions of health, and cardiovascular risk factors relate to knowledge? (3) Is there a relationship between knowledge and behavior? (4) What might explain apparent inconsistencies between knowledge and behavior? The data used in this paper derive from a random sample of 732 men and women form the greater Boston area. We assessed cardiovascular risk factor knowledge by asking respondents what specific steps a person could take to make a heart attack or stroke less likely. Risk factors (including physiological measures), sociodemographic factors, and self-perceptions of health also were measured. Results showed that respondents were most knowledgeable about the relationships of exercise and cholesterol to heart disease. Knowledge was related positively to education, being female, and exercising. When we compared knowledge with behavior, results showed that for smokers and those who were overweight, risk was related to awareness, thus suggesting that knowledge does not lead necessarily to risk-reducing behavior. Implications of these results in terms of education and prevention are discussed.

Results of 1,000 single-layer continuous polypropylene intestinal anastomoses.

Between 1979 and 1988, we created intestinal anastomoses in 1,000 patients using a single-layer, continuous suturing technique and a polypropylene suture. The technique is easily learned, flexible in its application, and incurs less cost than most other techniques. The anastomoses involved all levels of the colon and the upper (intraperitoneal and extraperitoneal) rectum. All patients were followed for a minimum of 1 year. The clinically suspected anastomotic leak rate was 1%. Other morbidity included would complications (2%), obstruction of the small intestine (2%), anastomotic stricture (1%), and death (1%). No death was due to anastomotic complications. These rates of complications are comparable with, and in many instances lower than, those reported with other techniques of intestinal anastomosis.

Reliability and validity of the Child and Adolescent Trial for Cardiovascular Health (CATCH) Food Checklist: a self-report instrument to measure fat and sodium intake by middle school students.

OBJECTIVE: To develop a scoring algorithm and evaluate the reliability and validity of scores from the Child and Adolescent Trial for Cardiovascular Health (CATCH) Food Checklist (CFC) as measures of total fat, saturated fat, and sodium intake in middle school students. DESIGN: Randomized, controlled trial in which participants were assigned to 1 of 3 study protocols that varied the order of CFC and 24-hour dietary recall administration. Criterion outcomes were percent energy from total fat, percent energy from saturated fat, and sodium intake in milligrams. SUBJECTS/SETTING: A multiethnic sample (33% ethnic and racial minorities) of 365 seventh-grade students from 8 schools in 4 states. STATISTICAL ANALYSES: Multivariable regression models were used to calibrate the effects of individual food checklist items; bootstrap estimates were used for cross-validation; and kappa statistics, Pearson correlations, t tests, and effect sizes were employed to assess reliability and validity. RESULTS: The median same-day test-retest reliability kappa for the 40 individual CFC food items was 0.85. With respect to item validity, the median kappa statistic comparing student choices to those identified by staff dietitians was 0.54. Test-retest reliability coefficients ranged from 0.84 to 0.89 for CFC total nutrient scores. Correlations between CFC scores and 24-hour recall values were 0.36 for total fat, 0.36 for saturated fat, and 0.34 for sodium; CFC scores were consistent with hypothesized gender differences in nutrient intake. APPLICATIONS/CONCLUSIONS: The CFC is a reliable and valid tool for measuring fat, saturated fat, and sodium intake in middle school students. Its brevity and ease of administration make the CFC a cost-effective way to measure middle school students' previous day's intake of selected nutrients in school surveys and intervention studies.

Sociocultural factors associated with smoking behavior by Puerto Rican adolescents in Boston.

This study examined cigarette smoking among Puerto Rican adolescents in the Boston area in its sociocultural context by describing who uses cigarettes, and by identifying factors that encourage or discourage cigarette use. The study, conducted from 1986-87, used two approaches. The first was to survey 605 Puerto Rican households with adolescents 11-20 years old. Households were identified from a random sample of census blocks in five neighborhoods. In each household, interviews were completed with one adolescent and his or her female caretaker. The second approach was to conduct ethnographic interviews with 40 adolescents selected through a purposive sample of survey respondents from three of the study neighborhoods. Bivariate and multivariate statistical analyses were used to examine the relationships between smoking behavior and characteristics of the adolescents. The results of these analyses were examined in light of the ethnographic data. Overall, 13.7% reported smoking in the month preceding the interview. Smoking was most prevalent among males 17-20. Patterns of smoking were associated with teens' social networks. The Puerto Rican adolescents in this study were more likely to smoke when their friends and household members smoked, if they participated in recreational activities such as sports or unsupervised games, and if they were not in school. These effects varied according to the gender of the respondent.

A self-efficacy scale for HIV risk behaviors: development and evaluation.

To measure self-efficacy with respect to risk behaviors for HIV infection, a set of questionnaire items was developed regarding condom use, drug use with friends, and negotiations with potential sex partners. These items were tested with a sample of Latinos aged 14 to 22 years in two New England cities. A nine-item self-efficacy scale was found to have a high level of internal consistency (Cronbach's alpha = .77). Reliability coefficients were similar for men, women, and both English- and Spanish-speaking respondents. Strong associations with recent performance accomplishments, as specified in Bandura's social cognitive theory, support the construct validity of the scale.

Quality of Medicare-reimbursed home health care.

We investigated the prevalence of quality of care deficiencies in 4,324 Medicare-reimbursed episodes of care provided by 47 home health agencies. The quality of care protocol consisted of a process-oriented, systematic record review by a trained nurse reviewer. Results suggest that an estimated 14.4% of home health care episodes had quality deficiencies with the potential for or actual adverse effects on the patient. Multivariate analyses revealed that the complexity of patients' needs increased the likelihood and severity of the quality problems. Agency ownership was not related to risk of a quality problem, but regional variation in agency effects was observed. Specific problem areas were identified that suggested several ways that home health care could be improved.

Do blacks and whites differ in reporting Rose Questionnaire angina? Results of the Boston Health Care Project.

We investigated the prevalence of angina (as determined by the Rose Questionnaire) in a random sample of African-American and white adults, aged 44 to 75 years, in three Boston (Mass) neighborhoods. Telephone interviews were completed by 2030 eligible subjects (response rate = 87.9%). A sample of 737 persons who had never been hospitalized for a heart attack also participated in a home visit. The prevalence of Rose angina was 7.0% in black women, 4.8% in white women, 5.0% in black men, and 5.7% in white men (P = .37). In both racial groups, respondents with diagnosed cardiovascular conditions, those taking cardiovascular medications, and those living alone were more likely to report angina than were other respondents. Blacks were more likely to report angina if they felt they were not getting needed medical care. Risk of angina declined with age among whites. In the home visit sample, the presence of major electrocardiogram abnormalities was also associated with angina. Rose angina appears to be influenced by similar risk factors in both blacks and whites.

Perioral dermatitis with histopathologic features of granulomatous rosacea: successful treatment with isotretinoin.

A young woman with a persistent eruption of small granulomas about the mouth and chin was studied and granulomatous perioral dermatitis was diagnosed. Some authorities consider that perioral dermatitis is a circumscribed variant of rosacea; the findings in this case tend to show a relationship between the two conditions. Once conventional therapies failed to result in a response, the eruption cleared, leaving pitted, atrophic scarring after a twenty week course of isotretinoin treatment.

Dinitrochlorobenzene immunotherapy of human warts.

A joint clinical study was conducted to test the effectiveness of topical dinitrochlorobenzene ointment in the treatment of warts. The feasibility of this therapeutic modality was demonstrated by the fact that warts completely cleared in more than 80 percent of the eighty-four patients enrolled in the study. Healing time average from three to six weeks. Complications incurred are presented and ways to minimize them are reviewed.

Plating of canine scapular fractures.

The purpose in this study was to determine whether there was a significance difference between conservative management and plating of scapular body fractures. Bilateral scapular body fractures were created in 10 dogs. The left scapula in each dog was treated by open reduction and plating of the scapular spine. The right scapula was not treated. Plating enhanced healing and early return of function, but there was no significant difference in the long-term results.

Adolescent involvement in Kansas City gangs.

The authors present information to enlighten physicians on the subject of adolescent gang involvement. Discussion includes explanations of who gets involved in these gangs, why they get involved and why it is important to identify youths who may be involved with gangs.

Time-of-flight methods in MR angiography.

Magnetic resonance angiography is a promising new technique for vascular imaging. MRA is based on gradient recalled acquisitions to maximize flow-related enhancement. The two major methods of MRA are time-of-flight and phase contrast. This article examines the time-of-flight method, and also includes a discussion of hemodynamics and the effects of scanning parameters.