Color, composition, and thermal environment of Kuiper Belt object (486958) Arrokoth.

The outer Solar System object (486958) Arrokoth (provisional designation 2014 MU69) has been largely undisturbed since its formation. We studied its surface composition using data collected by the New Horizons spacecraft. Methanol ice is present along with organic material, which may have formed through irradiation of simple molecules. Water ice was not detected. This composition indicates hydrogenation of carbon monoxide-rich ice and/or energetic processing of methane condensed on water ice grains in the cold, outer edge of the early Solar System. There are only small regional variations in color and spectra across the surface, which suggests that Arrokoth formed from a homogeneous or well-mixed reservoir of solids. Microwave thermal emission from the winter night side is consistent with a mean brightness temperature of 29 ± 5 kelvin.

Antarctic offshore polynyas linked to Southern Hemisphere climate anomalies.

Offshore Antarctic polynyas-large openings in the winter sea ice cover-are thought to be maintained by a rapid ventilation of deep-ocean heat through convective mixing. These rare phenomena may alter abyssal properties and circulation, yet their formation mechanisms are not well understood. Here we demonstrate that concurrent upper-ocean preconditioning and meteorological perturbations are responsible for the appearance of polynyas in the Weddell Sea region of the Southern Ocean. Autonomous profiling float observations-collected in 2016 and 2017 during the largest polynyas to form near the Maud Rise seamount since 1976-reveal that the polynyas were initiated and modulated by the passage of severe storms, and that intense heat loss drove deep overturning within them. Wind-driven upwelling of record strength weakened haline stratification in the upper ocean, thus favouring destabilization in 2016 and 2017. We show that previous Weddell polynyas probably developed under similarly anomalous conditions, which are associated with a mode of Southern Hemisphere climate variability that is predicted to strengthen as a result of anthropogenic climate change.

Towards total voluntary non-remunerated blood donation in Trinidad and Tobago

Objective: Investigate the historical origins of voluntary nonremunerated blood donation (VNRD) and describe a UWI-led initiative. Design and Methodology: Historical review was performed using internet searches, documents, books, journals, interviews. Data from blood donor cards and Microsoft Excel spreadsheets was collected prospectively and analysed retrospectively. Donors were classified by age, gender, donation status (first-time or repeat) and donation outcome (accepted or deferred). The prevalence of transfusion transmissible infections and deferrals in donors was compared to the national donor pool using Chi square analysis to compare proportions and a p value < 0.05 to assign statistical significance. Results: Human to human blood transfusion and voluntary non-remunerated blood donation were first practised in metropolitan countries and amplified in large scale community blood donation programmes during World War II. Blood donation systems based on individual, transactional donations emerged in most developing countries, including Trinidad and Tobago, causing low donation rates, chronic blood shortage, unequal access, high donor infections and high donor deferrals. A voluntary non-remunerated blood donation programme started by the UWI Blood Donor Foundation and the North Central Health Authority has collected 660 units of blood in its first three years, the majority from persons aged 16 -25 age (52%), females (52%) and repeat donors (51%). Deferrals were < 10% and total transfusion transmissible infections in donors 0.9% compared with 43.6% and 2.4 % respectively (p < 0.05 for both) for the involuntary national donor pool. Conclusion: This model could be extended to all blood donation centres and the community to achieve 100% VNRD.

The formation of Charon's red poles from seasonally cold-trapped volatiles.

A unique feature of Pluto's large satellite Charon is its dark red northern polar cap. Similar colours on Pluto's surface have been attributed to tholin-like organic macromolecules produced by energetic radiation processing of hydrocarbons. The polar location on Charon implicates the temperature extremes that result from Charon's high obliquity and long seasons in the production of this material. The escape of Pluto's atmosphere provides a potential feedstock for a complex chemistry. Gas from Pluto that is transiently cold-trapped and processed at Charon's winter pole was proposed as an explanation for the dark coloration on the basis of an image of Charon's northern hemisphere, but not modelled quantitatively. Here we report images of the southern hemisphere illuminated by Pluto-shine and also images taken during the approach phase that show the northern polar cap over a range of longitudes. We model the surface thermal environment on Charon and the supply and temporary cold-trapping of material escaping from Pluto, as well as the photolytic processing of this material into more complex and less volatile molecules while cold-trapped. The model results are consistent with the proposed mechanism for producing the observed colour pattern on Charon.

The small satellites of Pluto as observed by New Horizons.

The New Horizons mission has provided resolved measurements of Pluto's moons Styx, Nix, Kerberos, and Hydra. All four are small, with equivalent spherical diameters of ~40 kilometers for Nix and Hydra and ~10 kilometers for Styx and Kerberos. They are also highly elongated, with maximum to minimum axis ratios of ~2. All four moons have high albedos (~50 to 90%) suggestive of a water-ice surface composition. Crater densities on Nix and Hydra imply surface ages of at least 4 billion years. The small moons rotate much faster than synchronous, with rotational poles clustered nearly orthogonal to the common pole directions of Pluto and Charon. These results reinforce the hypothesis that the small moons formed in the aftermath of a collision that produced the Pluto-Charon binary.

Surface compositions across Pluto and Charon.

The New Horizons spacecraft mapped colors and infrared spectra across the encounter hemispheres of Pluto and Charon. The volatile methane, carbon monoxide, and nitrogen ices that dominate Pluto's surface have complicated spatial distributions resulting from sublimation, condensation, and glacial flow acting over seasonal and geological time scales. Pluto's water ice "bedrock" was also mapped, with isolated outcrops occurring in a variety of settings. Pluto's surface exhibits complex regional color diversity associated with its distinct provinces. Charon's color pattern is simpler, dominated by neutral low latitudes and a reddish northern polar region. Charon's near-infrared spectra reveal highly localized areas with strong ammonia absorption tied to small craters with relatively fresh-appearing impact ejecta.

The Pluto system: Initial results from its exploration by New Horizons.

The Pluto system was recently explored by NASA's New Horizons spacecraft, making closest approach on 14 July 2015. Pluto's surface displays diverse landforms, terrain ages, albedos, colors, and composition gradients. Evidence is found for a water-ice crust, geologically young surface units, surface ice convection, wind streaks, volatile transport, and glacial flow. Pluto's atmosphere is highly extended, with trace hydrocarbons, a global haze layer, and a surface pressure near 10 microbars. Pluto's diverse surface geology and long-term activity raise fundamental questions about how small planets remain active many billions of years after formation. Pluto's large moon Charon displays tectonics and evidence for a heterogeneous crustal composition; its north pole displays puzzling dark terrain. Small satellites Hydra and Nix have higher albedos than expected.

Extended family caring for children orphaned by AIDS: balancing essential work and caregiving in a high HIV prevalence nations.

While over 90 per cent of the 15 million children who have been orphaned by HIV/AIDS are cared for by family members, there is little information about whether adults can meet orphans' essential caregiving needs while working to economically survive. Using a survey we conducted in Botswana of 1033 working adults, we analyse the experience of adults who are caring for orphans. Over one-third of working adults were caring for orphans and many with few financial resources: 82% were living on household incomes below US$10 purchasing power parity adjusted per person per day. Because of their caregiving responsibilities, they were less able to supplement income with overtime, weekend, evening, or night work. At the same time caregiving responsibilities meant orphan caregivers spent fewer hours caring for their own children and other family members. Nearly half of orphan caregivers had difficulties meeting their children's needs, and nearly 75% weren't able to meet with children's teachers. Pay loss at work compounded the problems: One-quarter of orphan caregivers reported having to take unpaid leave to meet sick childcare needs and nearly half reported being absent from work for children's routine health care. This paper makes clear that if families are to provide adequate care for orphans while economically surviving there needs to be increases in social supports and improvements in working conditions.

The impact of welfare reform on parents' ability to care for their children's health.

OBJECTIVES: Most of the national policy debate regarding welfare assumed that if middle-income mothers could balance work while caring for their children's health and development, mothers leaving welfare for work should be able to do so as well. Yet, previous research has not examined the conditions faced by mothers leaving welfare for work. METHODS: Using data from the National Longitudinal Survey of Youth, this study examined the availability of benefits that working parents commonly use to meet the health and developmental needs of their children; paid sick leave, vacation leave, and flexible hours. RESULTS: In comparison with mothers who had never received welfare, mothers who had been on Aid to Families with Dependent Children were more likely to be caring for at least 1 child with a chronic condition (37% vs 21%, respectively). Yet, they were more likely to lack sick leave for the entire time they worked (36% vs 20%) and less likely to receive other paid leave or flexibility. CONCLUSIONS: If current welfare recipients face similar conditions when they return to work, many will face working conditions that make it difficult or impossible to succeed in the labor force at the same time as meeting their children's health and developmental needs.

Parental availability for the care of sick children.

OBJECTIVE: Parents have always played a critical role in the care of sick children. Although parents' roles remain crucial to children's health, parental availability has declined during the past half century. The percentage of women with preschool children who work has risen almost fivefold in 45 years from 12% in 1947 to 58% in 1992. The percentage of women in the paid work force with school-aged children has almost tripled in the same period, from 27.3% to 75.9%. Research has examined the effects of a variety of parental work conditions on children. However, past research has not examined how working conditions affect the ability of parents to care for their sick children. In this article, we examine how often the children of working parents get sick and whether parents receive enough paid leave to care for their sick children. METHODOLOGY: This analysis makes use of two national surveys, which provide complementary information regarding the care of sick children. The National Longitudinal Survey of Youth is a longitudinal survey of a nationally representative probability sample of 12,686 men and women; the National Medical Expenditure Survey is a panel survey of 34,459 people. First, we estimated the family illness burden. Second, we looked in detail at the number of days of sick leave mothers had. Third, we examined whether mothers who had sick leave had it consistently during a 5-year period. Finally, we conducted a logistic regression to determine what factors were significant predictors of both lacking sick leave. RESULTS: More than one in three families faced a family illness burden of 2 weeks or more each year. Yet, 28% of mothers had sick leave none of the time they were employed between 1985 and 1990. Employed mothers of children with chronic conditions had less sick leave than other employed mothers. Thirty-six percent of mothers whose children had chronic conditions had sick leave none of the time they were employed. Although 20% of working parents who did not live in poverty lacked sick leave, 38% of parents who did live in poverty lacked sick leave. The problem is also more marked for nonwhite parents. Although 23% of working white parents lacked paid sick leave, 31% of nonwhite parents lacked sick leave. One in six families that lacked sick leave had to cover for more than 4 weeks of family illness during the year. CONCLUSION: In 1993, the US Congress passed the Family and Medical Leave Act (FMLA). However, by limiting the medical leave to the care of major illnesses, primarily those requiring hospitalization, the FMLA does not address the majority of children's sick care needs. For the common childhood illnesses that are not covered by the FMLA, employed parents often must rely on their sick leave if they are to care for their sick children themselves. Yet, we found that many employed parents lack sick leave. This is particularly true of parents of children with chronic conditions and poor and minority families.

The relationship of the subarachnoid injection of blood and blood fractions with cardiac rate change and arrhythmias.

The relationship of subarachnoid hemorrhage and cardiac arrhythmias was studied utilizing a Sprague-Dawley rat model. A total of 30 male animals were divided into five groups and given subarachnoid injections of either blood, blood fractions, or control substances. Blood pressure, intracranial pressure, serum electrolytes, arterial blood gases, hypothalamic multiple unit activity and an electrocardiogram were concurrently monitored. Cardiac arrhythmias were graded on a 0 to 4 + objective scale. Control parameter values were similar for all animals. Arrhythmias, hypotension, and decreased hypothalamic multiple unit activity were seen with infusion of whole blood and packed red blood cells. Packed red blood cells were statistically demonstrated to have the most potent arrhythmogenic effect. Cardiac histopathology revealed myocardial contraction band lesions most predominant in the packed red blood cell group. In addition, significant QT interval prolongation was observed after subarachnoid injection of either whole blood or packed red blood cells. These findings indicate that packed red blood cells, or a component thereof, may play an important role in the etiology of immediate (i.e. acute) post subarachnoid hemorrhage induced cardiac arrhythmias.

Vascular impairment and free tissue transfer in the lower extremity.

Fourteen patients with arteriosclerotic peripheral vascular disease and extensive tissue defects of the lower extremity, underwent microsurgical reconstruction using free tissue ("free flap") transfer. It was possible to provide coverage in ten of these patients. Analysis of this small series showed that only six of these ten patients were able to resume unassisted ambulation. The authors discuss technical aspects of microsurgical reconstruction in this unfavorable group of patients. Analysis of this small series suggest that: (1) inadequate patient motivation, and (2) inability to form granulation tissue in the soft tissue defect, either before or after a vascular reconstructive procedure, are both strong contraindications to microvascular free flap reconstruction in patients with arteriosclerotic peripheral vascular insufficiency of the lower extremity.

Open tibial fractures with severe soft-tissue loss. Limb salvage compared with below-the-knee amputation.

The long-term outcomes and the quality of life were studied in patients who had had an open fracture of the tibial shaft with severe soft-tissue loss. Limb salvage with a free flap was attempted in twenty-seven patients (sixteen of whom had a successful procedure and were examined personally by us), while eighteen patients were managed concurrently with an early below-the-knee amputation. Soft-tissue coverage was successful in all but one patient in whom limb salvage had been attempted. Ultimately, however, five extremities were amputated, with an infection at the site of a non-union being the most common reason for amputation. The patients who had had limb salvage had more complications (p < 0.001), more operative procedures (p < 0.001), and a longer stay in the hospital (p < 0.05) than the patients who had had an early below-the-knee amputation. The long-term functional results for sixteen patients who had had a successful limb-salvage procedure (average duration of follow-up, thirty-five months) were compared with those for eighteen patients who had had a below-the-knee amputation (average duration of follow-up, forty-four months). The patients who had had a successful limb-salvage procedure took significantly more time to achieve full weight-bearing (p < 0.05), were less willing or able to work (p < 0.01), and had higher hospital charges (p < 0.006) than the patients who had been managed with an early below-the-knee amputation. They also had a significant decrease in motion at the ankle and subtalar joint in the injured leg compared with the contralateral leg (p < 0.001). A quality-of-life evaluation was possible for only thirteen of the patients who had had a successful limb-salvage procedure and for sixteen of the patients who had had a below-the-knee amputation. The two groups were similar in terms of their responses, but significantly more patients who had had limb salvage considered themselves severely disabled (p < 0.05). They also had more problems with the performance of occupational and recreational activities (p < 0.05). This study confirmed the reliability of modern microvascular free tissue techniques for the coverage of large soft-tissue defects associated with tibial fractures. It also showed that complications and difficulties in the restoration of osseous union are common and may be directly related to the less satisfactory functional, occupational, recreational, and quality-of-life outcomes that are seen in many patients who have had limb salvage.(ABSTRACT TRUNCATED AT 400 WORDS)

Concurrent radiation therapy, 5-fluorouracil, and cisplatin for stage II, III, and IV, node-negative, squamous cell head and neck cancer. Results and surgical implications.

METHODS: Between 1983 and 1989, 42 patients with Stage II, III, and IV, node-negative, squamous cell head and neck cancer were treated with concurrent 5-fluorouracil, cisplatin, and radiation therapy. Two courses of chemotherapy with 30 Gy of concurrent radiation therapy were to be followed in all patients by definitive surgery and then an additional 30 Gy of radiation therapy and one to two courses of chemotherapy. The patients who achieved a complete response to the initial induction treatment, however, did not undergo surgery. RESULTS: After the completion of all therapy, 41 of the 42 patients (98%) were considered disease-free. Only 4 of these 41 had relapses, for a projected Kaplan-Meier disease-free survival rate of 86%. Treatment failure occurred in no patients with Stage II, 1 of 17 patients with Stage III, and 4 of 14 patients with Stage IV disease. Of the 42 patients, 23 (55%) did not require surgery after achieving a complete response to induction therapy, and only 1 of these 23 patients subsequently had a relapse. CONCLUSIONS: Although the value of adding chemotherapy to conventional treatment remains unproven in squamous cell head and neck cancer, this treatment schedule appears promising in node-negative disease. Randomized trials will be necessary, however, to validate the efficacy of this approach and confirm the suggestion by the authors that surgery can be avoided in most patients with N0 disease.

Vein grafts in reconstructive microsurgery of the lower extremity.

This paper describes surgical techniques and results of lower extremity microsurgical reconstruction using vein grafts. During a 5 year period, free tissue transfers were used to reconstruct 118 lower extremity defects in 109 patients. In 28 of these cases (24%), saphenous vein grafts were used when reconstruction would otherwise have been difficult or impossible. A preliminary arteriovenous fistula was established between the proximal arterial source and the final venous drainage in the majority (26) of cases. Venous drainage was left intact at the point of entry into the deep venous system in 23 cases. Three complications included anastomotic clotting in 2 patients and postoperative blow-out of the vein graft in another; all were treated without flap loss. Flap survival was 86% in vein grafted patients and 94% in those cases in which vein grafts were not used. Flap loss was related in each case to the nature of the pre-existing condition, rather than to vein grafting per se.

Long-term results after chemoradiotherapy for locally confined squamous-cell head and neck cancer.

The long-term results after simultaneous chemoradiotherapy in 54 patients with previously untreated or minimally treated, locally confined (M0) squamous-cell carcinoma of the head and neck are presented. Multiple concurrent courses of radiation therapy and chemotherapy with cisplatin and a four-day 5-fluorouracil infusion were given. Twenty-eight patients underwent definitive surgery and 26 were treated without surgical resection. Treatment-associated toxicity was significant, including mucositis, myelosuppression, and a mean 12% loss of initial body weight. Of the 54 patients, 51 were ultimately rendered disease free by this combined modality protocol. With a follow-up ranging from 42-68 months, the projected Kaplan-Meier relapse-free survival for the entire patient cohort is 70%, with all relapses occurring within 17 months of patient entry. The projected Kaplan-Meier relapse-free survival for patients with Stage IV disease is 62%. The durability of these remissions suggests that there is a significant likelihood of cure in all patients with locally confined disease, and justifies comparative trials with standard treatment.

Long saphenous vein grafts as an aid to microsurgical reconstruction of the trunk.

The authors describe a method of closing truncal defects using free-tissue transfer when neither local tissue or vascular access are available. The long saphenous vein is dissected free as far distally as necessary and turned up, leaving its upper drainage intact. The distal end is then anastomosed to the femoral artery to create a temporary arteriovenous loop. After placing an appropriate free flap in the defect, the A-V loop is divided and used to provide both arterial supply and venous drainage for the flap. Anatomy, technique, and representative cases in which this method has been used for closing traumatic tissue defects of the trunk are presented and discussed.

Treatment of oral squamous cell carcinoma with simultaneous chemotherapy and radiation: results and surgical implications.

Thirty-seven patients with oral squamous cell carcinoma, many with advanced disease, were treated initially with a protocol using simultaneous intravenous 5-fluorouracil (5-FU) cis-platinum, and radiation. Twenty-two patients (62%) experienced complete remission after one cycle of therapy. Fifteen patients (38%) demonstrated an incomplete response; surgical resection was possible in 14 of these 15 patients. A second cycle of chemoradiotherapy was administered to all 37 patients. After this treatment resection is possible for some patients who are initially inoperable, and surgery is necessary only for those patients (38%) who show an incomplete remission after the first cycle of therapy and for those who present initially with bony invasion. Furthermore, the treatment of cervical nodes and intraoral disease may be divorced and the extent of surgery may be reduced for many patients. A 5-year survival of 76% is predicted for this group of patients. The described protocol shows promise for treatment of oral squamous cell carcinoma.

Simultaneous versus sequential combined technique therapy for squamous cell head and neck cancer.

Forty-eight patients with locally confined (M0) squamous cell head and neck cancer were prospectively randomized to receive either simultaneous (SIM) or sequential (SEQ) combined technique therapy with a 5-fluorouracil infusion, a cisplatin bolus injection, and radiation therapy. Patients with residual resectable disease underwent surgery after induction therapy, whereas those achieving a complete response to induction did not require surgery. Patients on the two treatment arms were equivalent in all measured variables, including disease extent. Toxicities of the SIM and SEQ arms also were equivalent except for mucositis and the resultant weight loss, which were more severe on the SIM arm (P = 0.002). With a follow-up time ranging from 9 to 41 months, seven of the 24 SIM patients and 14 of the 24 SEQ patients are considered treatment failures. The relapse-free survival is significantly better on the SIM arm (P = 0.03), although an overall survival advantage has not yet been demonstrated (P = 0.13). The achievement of a complete response after induction therapy correlates with both the relapse-free (P = 0.0005) and overall (P = 0.05) survival, and the likelihood of an induction complete response also is significantly better for those treated with the SIM schedule (P = 0.02). Eighteen patients did not require surgery after achieving an induction complete response. Relapse-free survival does not appear to be compromised in this patient subset.