Predicting rare earth elements concentration in coal ashes with multi-task neural networks

The increasing demand for rare earth elements (REEs) makes them a scarce strategic resource for technical developments. In that regard, harvesting REEs from coal ashes-a waste byproduct from coal power plants-offers an alternative solution to conventional ore-based extraction. However, this approach is bottlenecked by our ability to screen coal ashes bearing large concentrations of REEs from feedstocks-since measuring the REE content in ashes is a time-consuming and costly task requiring advanced analytical tools. Here, we propose a machine learning approach to predict the REE contents based on the bulk composition of coal ashes, easily measurable under the routine testing protocol. We introduce a multi-task neural network that simultaneously predicts the contents of different REEs. Compared to the single-task model, this model exhibits notably improved accuracy and reduced sensitivity to noise. Further model analyses reveal key data patterns for screening coal ashes with high REE concentrations. Additionally, we showcase the utilization of transfer learning to improve the adaptability of our model to coal ashes from a distinct source.

Exploring Models of Exposure to Primary Care Careers in Training: a Narrative Review

Multiple models of clinical exposure to primary care exist within undergraduate medical education (UME) and graduate medical education (GME). In this narrative review, we explore the evidence behind these different models of exposure, their alignment with positive promoters of primary care careers, and the pros and cons of each. Without positive exposure to primary care during training, sustaining the future primary care work force becomes increasingly challenging. Here, we explore multiple models of clinical exposure in UME, including longitudinal integrated clerkships, primary care tracks, and primary care clerkships. Within GME, we will review the impact of primary care tracks, Area Health Education Centers, block scheduling models, and continuity clinic scheduling models. The goal of this narrative review is to allow educators to think broadly and intentionally about the array of models to develop positive primary care experiences and perceptions in training, ultimately sustaining the primary care workforce.

Quality Improvement Within a Mental Health Setting: Alcohol Detoxification

Aims We describe a clinical audit on alcohol detoxification, using NICE guidelines as a comparable standard. NICE guidelines recommend completing a thorough alcohol history, documentation of a physical examination including screening for Wernicke's encephalopathy, monitoring of vital signs and liver investigations. Breath alcohol level and standardised assessment of withdrawal should be completed in addition to documentation of chlordiazepoxide and thiamine prescriptions. The reported mental health service completed the first cycle of the audit as part of a large-scale, international audit on alcohol detoxification by the Prescribing Observatory for Mental Health, UK (POMH-UK). Two additional audit cycles were completed within the service to ensure continuous quality improvement and clinical effectiveness. Methods Retrospective chart reviews were performed for admissions within pre-defined 6-month periods. Inclusion criteria: ICD-10 F10 diagnosis; prescription of alcohol detoxification schedule. Results This mental health service demonstrated greater compliance with the NICE standards in comparison to other services in the POMH-UK audit. The second-cycle audit showed increased compliance in most areas compared to the initial results. The third-cycle audit focused on two specific areas that required improvement to optimise quality improvement - Breath Alcohol Level and Clinical Institute of Withdrawal Assessment, documentation of which improved from 79% to 85% and 39% to 91% respectively in the final audit cycle. Conclusion The results of this audit indicate that adherence to defined clinical standards within this mental health service exceeds that of the benchmark POMH-UK data. The effectiveness of electronic patient records in improving adherence to set clinical standards, specifically in relation to documentation of clinical parameters is evident. The report also confirms continued improved results with each audit cycle within the service.

Solidification/stabilization of flue gas desulfurization brine and coal fly ash for heavy metals and chloride immobilization: Effects of S/S conditions and zero-valent-iron pretreatment

Effective management of flue-gas-desulfurization (FGD) wastewater and coal-combustion-residues (CCRs) are major challenges in the coal-fired power industry. The zero-liquid-discharge (ZLD) method of combining FGD brines and CCRs in solidification/stabilization (S/S) is promising due to its potential of treating both wastes in the same process. This study evaluated the performance of such a ZLD method for immobilizing heavy metals (Se, As, Cd and Cr) and chloride in FGD wastewater and/or CCRs. Effects of different coal fly ash (bituminous (BCFA) and sub-bituminous (SCFA)), activating agent (Portland cement (PC) and lime) and pretreatment of brines by zero valent iron (ZVI) on the S/S process were evaluated. Short-term and long-term leaching tests were conducted to evaluate performance of the S/S solids in pollutant retainment. The pre-treatment of FGD brine by ZVI enhanced the retainment of heavy metals when BCFA was used, but not when SCFA was used since it already performed quite well without ZVI pretreatment. Quantitative X-ray diffraction and scanning electron microscopy analyses strongly indicated the formation of Friedel's salt, Ca₂Al(OH)₆(Cl,OH)·2H₂O, is critical in the retainment of heavy metals and chloride. SCFA contained higher lime and reactive aluminate contents than BCFA; thus, S/S solids made with SCFA contained higher amounts of Friedel's salt.

Near-Sun observations of an F-corona decrease and K-corona fine structure

Remote observations of the solar photospheric light scattered by electrons (the K-corona) and dust (the F-corona or zodiacal light) have been made from the ground during eclipses¹ and from space at distances as small as 0.3 astronomical units^2-5 to the Sun. Previous observations^6-8 of dust scattering have not confirmed the existence of the theoretically predicted dust-free zone near the Sun^9-11. The transient nature of the corona has been well characterized for large events, but questions still remain (for example, about the initiation of the corona¹² and the production of solar energetic particles¹³) and for small events even its structure is uncertain¹⁴. Here we report imaging of the solar corona¹⁵ during the first two perihelion passes (0.16-0.25 astronomical units) of the Parker Solar Probe spacecraft¹³, each lasting ten days. The view from these distances is qualitatively similar to the historical views from ground and space, but there are some notable differences. At short elongations, we observe a decrease in the intensity of the F-coronal intensity, which is suggestive of the long-sought dust free zone^9-11. We also resolve the fine-scale plasma structure of very small eruptions, which are frequently ejected from the Sun. These take two forms: the frequently observed magnetic flux ropes^12,16 and the predicted, but not yet observed, magnetic islands^17,18 arising from the tearing-mode instability in the current sheet. Our observations of the coronal streamer evolution confirm the large-scale topology of the solar corona, but also reveal that, as recently predicted¹⁹, streamers are composed of yet smaller substreamers channelling continual density fluctuations at all visible scales.

Are extreme distal periprosthetic supracondylar fractures of the femur too distal to fix using a lateral locked plate?

It is unclear whether there is a limit to the amount of distal bone required to support fixation of supracondylar periprosthetic femoral fractures. This retrospective multicentre study evaluated lateral locked plating of periprosthetic supracondylar femoral fractures and compared the results according to extension of the fracture distal with the proximal border of the femoral prosthetic component. Between 1999 and 2008, 89 patients underwent lateral locked plating of a supracondylar periprosthetic femoral fracture, of whom 61 patients with a mean age of 72 years (42 to 96) comprising 53 women, were available after a minimum follow-up of six months or until fracture healing. Patients were grouped into those with fractures located proximally (28) and those with fractures that extended distal to the proximal border of the femoral component (33). Delayed healing and nonunion occurred respectively in five (18%) and three (11%) of more proximal fractures, and in two (6%) and five (15%) of the fractures with distal extension (p = 0.23 for delayed healing; p = 0.72 for nonunion, Fisher's exact test). Four construct failures (14%) occurred in more proximal fractures, and three (9%) in fractures with distal extension (p = 0.51). Of the two deep infections that occurred in each group, one resolved after surgical debridement and antibiotics, and one progressed to a nonunion. Extreme distal periprosthetic supracondylar fractures of the femur are not a contra-indication to lateral locked plating. These fractures can be managed with internal fixation, with predictable results, similar to those seen in more proximal fractures.

Animal abuse and intimate partner violence: researching the link and its significance in Ireland - a veterinary perspective

Research on domestic violence has established a substantial association between intimate partner abuse and the abuse of children within the home. It is only recently however, that researchers have demonstrated the correlation between non-accidental injury in animals, and abuse of women by their intimate male partners. A growing body of evidence suggests that animal abuse can be an early indicator for other forms of violent behaviour. This research includes the responses of a sample of 23 women using refuge services in the Republic of Ireland. It investigates the connection between domestic violence and animal abuse, and ascertains if there is sufficient support service for animals and people relevant to domestic abuse. In the survey population, 57% of women reported witnessing one or more forms of abuse, or threats of abuse, of their pets. Five of which were reported to have resulted in the death of the pet. Eighty seven per cent of women felt a facility to accommodate pets would have made their decision to leave the family home easier. Four women disclosed that lack of such a service and concern for the welfare of their companion animals caused them to remain in their abusive relationships for longer than they felt appropriate. Nine families placed pets in the care of family or friends, one woman is unaware of the fate of her pet, while the pets of six families remained with the abusive male after his partner entered a refuge. The majority of women felt unable to talk to anyone about their fears for their pets' welfare. Many felt that there is no service which can provide temporary accommodation for womens' pets while they are in refuge. The results obtained support those found elsewhere in larger studies in the USA and UK, and demonstrate an association of animal abuse in households where there is reported domestic violence.

Poor nutritional status prior to peripheral blood stem cell transplantation is associated with increased length of hospital stay

The nutritional status of patients prior to peripheral blood stem cell transplantation (PBSCT) and its impact on length of hospital stay is not well described in the literature. The nutritional status of 66 consecutive patients (46 m:20 f); and the mean age 58.7+/-12.0 years was determined a maximum of 2 weeks pre-transplantation using the scored Patient-Generated-Subjective Global Assessment (PG-SGA). According to the global assessment, 73% patients were well nourished, 23% moderately malnourished and 4% severely malnourished. There was a significant difference in post transplant length of stay (mean difference+/-s.e.m. -7.0+/-2.1 days) between well-nourished and malnourished patients and a trend towards higher mortality in the malnourished group (2 vs 20%). Although 89% of patients described no problems eating, two or more nutrition impact symptoms were reported in 30% of patients. From stepwise multiple regression analysis, nutritional status as determined by PG-SGA score was significantly associated with length of stay, accounting for 12% of the variance. In conclusion, malnutrition prior to PBSCT is associated with increased length of stay. Routine nutrition assessment of patients prior to PBSCT should be undertaken.

A pilot plant study using a vertically moving biofilm process to treat municipal wastewater

The pilot plant study comprised the construction and monitoring of a new vertically moving biofilm system (VMBS) for treating municipal wastewater. The system operated on site for 11 months. The biofilm module in this system, consisting of high surface area plastic media, was vertically and repeatedly moved in cycles up into the air and down into the wastewater. The vertical movement of the biofilm module supplied sufficient oxygen for the removal of the organic carbon in the wastewater. The overall physical oxygen transfer coefficient (Kla) measured at the cycle speed of six cycles per minute was 2.53 per hour. During the pilot study, dissolved oxygen (DO) concentrations in the bulk fluid were in the range of 1.5-5 mg/l. It was found that the areal removal rate of filtered chemical oxygen demand (COD) was up to 35 g COD/(m(2)day) and the bulk fluid volumetric filtered COD removal rate was 2.62 kg COD/(m(3)day). The field experiment showed that clogging commonly found in other biofilm systems did not occur in this system. The power consumption was in the range of 0.09-0.25 k Wh/m(3) wastewater flow, 0.40-2.19 k Wh/kg COD removal and 1.24-1.74 k Wh/kg BOD removal. The new biofilm system offers potential for reduced reactor volumes, energy saving, simple construction and easy operation.

A fall prevention program for the home environment

Falls are the leading cause of injury, death, and disability among people older than 65. When elders fall, they sustain such injuries as hip, spine, hand, and/or pelvic fractures. The prognosis after such a fall is poor--only half of older adults hospitalized for hip fractures are able to return home or live independently again. Even without injury, falls cause a loss of confidence that results in reduced physical activity, increased dependency, and social withdrawal. As a home care agency dealing with a geriatric population, our goal was to develop a user-friendly fall prevention program that would promote multidisciplinary assessment and intervention. We have developed a preventive approach through which clinicians and patients can collaborate on preventing falls in the home and maintaining our patients' first priority: quality of life.

Cancer incidence in New York State acquired immunodeficiency syndrome patients

To identify cancers that occur at higher rates in acquired immunodeficiency syndrome (AIDS) patients, the cancer experience of New York State (NYS) AIDS patients aged 15-69 years who were diagnosed between 1981 and 1994 was compared with that of the NYS general population. Sex and HIV risk group-specific standardized incidence ratios (SIRs), post-AIDS relative risks, and trends of relative risks were calculated to determine cancer risk. Among non-AIDS-related cancers, elevated SIRs were found for Hodgkin's disease (male, 8.0; female, 6.4; heterosexually infected males, 31.3); cancer of the rectum, rectosigmoid, and anus (male, 3.3; female, 3.0); trachea, bronchus, and lung (male, 3.3; female, 7.5); and brain and central nervous system (male, 3.1; female, 3.4; heterosexually infected females, 23.8) cancers. Moreover, significant trends of increasing relative risks from the pre-AIDS to the post-AIDS period were found for cancers of the rectum, rectosigmoid, and anus; trachea, bronchus, and lung; skin; and connective tissues (all sites, p < 0.05) among males. For AIDS-related cancers in women, invasive cervical cancer had an overall SIR of 9.1 (95% confidence interval: 6.9, 10.8) and a post-AIDS relative risk of 6.5 (95% confidence interval: 4.1, 9.7). This population-based registry linkage analysis evaluates cancer risk in AIDS patients by sex and risk factors and adds evidence that HIV-associated immunosuppression increases the risks of specific types of cancer.

Evaluation of the dissemination of active support training in staffed community residences

Our aim was to replicate Active Support, a staff training intervention designed to increase the assistance given to adults with severe mental retardation living in community residences in order to increase their participation in activities. Training was conducted in 38 residences, involving 303 staff members and 106 persons with mental retardation. Active Support resulted in significant increases in assistance and engagement in activity. Significant correlations between participant abilities, receipt of assistance, and levels of engagement were found. Active Support was found to be of greater benefit to people with lower adaptive behavior and to have a diminishing value for people with higher adaptive behavior, implying that its implementation should be matched to the support needs of residents.

Enhancement of human immunodeficiency virus type 1-specific CD4 and CD8 T cell responses in chronically infected persons after temporary treatment interruption

Immunologic and virologic outcomes of treatment interruption were compared for 5 chronically human immunodeficiency virus (HIV)-infected persons who have maintained antiretroviral therapy-mediated virus suppression, as compared with 5 untreated controls. After a median interruption of 55 days of therapy accompanied by rebound of virus, reinitiated therapy in 4 of 5 subjects resulted in suppression of 98.86% of plasma virus load by 21-33 days and no significant decrease in CD4 T cell percentage from baseline. Increased T helper responses against HIV-1 p24 antigen (P=. 014) and interferon-gamma-secreting CD8 T cell responses against HIV-1 Env (P=.004) were present during interruption of therapy and after reinitiation of treatment. The remaining subject whose treatment was interrupted did not resume treatment and continued to have a low virus load (<1080 HIV-1 RNA copies/mL) and persistent antiviral cell-mediated responses. In summary, cellular immunity against autologous HIV-1 has the potential to be acutely augmented in association with temporary treatment interruption in chronically infected persons.

Discontinuation of prophylaxis against Mycobacterium avium complex disease in HIV-infected patients who have a response to antiretroviral therapy. Terry Beirn Community Programs for Clinical Research on AIDS

BACKGROUND

Several agents are effective in preventing Mycobacterium avium complex disease in patients with advanced human immunodeficiency virus (HIV) infection. However, there is uncertainty about whether prophylaxis should be continued in patients whose CD4+ cell counts have increased substantially with antiviral therapy.

METHODS

We conducted a multicenter, double-blind, randomized trial of treatment with azithromycin (1200 mg weekly) as compared with placebo in HIV-infected patients whose CD4+ cell counts had increased from less than 50 to more than 100 per cubic millimeter in response to antiretroviral therapy. The primary end point was M. avium complex disease or bacterial pneumonia.

RESULTS

A total of 520 patients entered the study; the median CD4+ cell count at entry was 230 per cubic millimeter. In 48 percent of the patients, the HIV RNA value was below the level of quantification. The median prior nadir CD4+ cell count was 23 per cubic millimeter, and 65 percent of the patients had had an acquired immunodeficiency syndrome-defining illness. During follow-up over a median period of 12 months, there were no episodes of confirmed M. avium complex disease in either group (95 percent confidence interval for the rate of disease in each group, 0 to 1.5 episodes per 100 person-years). Three patients in the azithromycin group (1.2 percent) and five in the placebo group (1.9 percent) had bacterial pneumonia (relative risk in the azithromycin group, 0.60; 95 percent confidence interval, 0.14 to 2.50; P=0.48). Neither the rate of progression of HIV disease nor the mortality rate differed significantly between the two groups. Adverse effects led to discontinuation of the study drug in 19 patients assigned to receive azithromycin (7.4 percent) and in 3 assigned to receive placebo (1.1 percent; relative risk, 6.6; P=0.002).

CONCLUSIONS

Azithromycin prophylaxis can safely be withheld in HIV-infected patients whose CD4+ cell counts have increased to more than 100 cells per cubic millimeter in response to antiretroviral therapy.

Outcome in children under 5 years of age with constipation: a prospective follow-up study

Constipation in the pre-school child is common and causes considerable distress to children and their parents. There is a lack of information regarding prognosis in this group of patients although some are clearly at risk of developing long-term difficulties with defaecation. We have previously reported characteristics of children under 5 years of age referred to hospital over a one-year period with idiopathic constipation. We now report outcome data after 18 months of follow-up in 41 of the original cohort of 42 children. We have also summarised what we regard as good practice in managing constipation in this age group. Eighteen months after initial outpatient assessment, the symptoms of constipation were reported to have resolved in 36 (88%), although seven of these were still needing regular laxative treatment. It was our subjective impression that the five children who apparently did not improve came from families that had a greater degree of psychosocial problems and where compliance with treatment was suspect. This study shows that with simple treatment measures and ongoing support, an optimistic prognosis can be given to families from the outset. The minority of pre-school children who do not improve may benefit from a more intensive psychological approach to management.

Validation of a malnutrition screening tool for patients receiving radiotherapy

Nutrition screening identifies individuals who are malnourished or at risk of becoming malnourished and who may benefit from nutrition support. The aim of this study was to validate a new malnutrition screening tool (MST) in cancer patients undergoing radiotherapy. The MST was compared with the subjective global assessment (SGA) of nutritional status. One hundred and six patients attending two cancer care centres in Australia were independently rated as well nourished or malnourished using SGA and at risk or not at risk of malnutrition using the MST. Convergent validity of the MST was established by determining the ability of the MST to predict SGA. According to SGA, 89% of the patients were well nourished and 11% were moderately malnourished. According to the MST, 28% of patients were at risk of malnutrition. The MST had a sensitivity of 100% and a specificity of 81%. The positive predictive value was 0.4 and the negative predictive value was 1.0. The MST is easy to use and is a strong predictor of nutritional status. The malnutrition screening tool is a simple, quick, valid tool that can be used to identify radiation oncology outpatients who are at risk of malnutrition.

Characteristics of children under 5 referred to hospital with constipation: a one-year prospective study

Constipation in the pre-school child can cause considerable distress to the individual and to the family. Most cases are idiopathic and with early diagnosis and effective treatment prognosis is good. In a teaching hospital paediatric unit, a year-long prospective study identified 42 new referrals for constipation in children under 5. Before referral for a specialist opinion there appeared to be considerable variation in both duration of symptoms and treatment given. Psychological factors in the family, as well as advice regarding simple behaviour modification and management of common secondary behavioural problems, seemed largely overlooked. Guidelines for for treating constipation in the community could help standardise and improve care. For children with refractory constipation referred to a specialist centre, we recommended a multidisciplinary assessment including paediatrician, paediatric surgeon and member of the child mental health team.

Magnetic resonance imaging in childhood intractable partial epilepsies: pathologic correlations

We conducted a retrospective single-blind study assessing the value of MRI in 44 children surgically treated for partial epilepsy, and correlated the MRI findings with the pathology in all cases. MRI revealed abnormalities in concordance with the clinical and electroencephalographic data in 84% of patients. Developmental neuronal migration pathology was present in 25% of patients and was relatively more common in the sensorimotor cortex. There was hippocampal sclerosis in 50% of patients with temporal lobe resection; however, only two of the 10 children with hippocampal sclerosis were below the age of 12 years. Similarly, ganglio-glial tumors were more common than astrocytomas in children below age 12. These results indicate that MRI is sensitive in the detection of pathologic abnormalities in most pediatric candidates for epilepsy surgery, and that the distribution and type of pathology appear to be age related in this population.

The significance of pleural elastica invasion by lung carcinomas

Invasion of visceral pleura by primary lung carcinomas is an important parameter in staging. The complex histology of visceral pleura requires special elastic stains for proper evaluation, yet only approximately 10% of peripheral lung carcinomas seen in consultation (S.J.U.) are thus assessed. The objective of this study was to examine the prognostic importance of microscopic visceral pleura invasion by lung carcinomas. Retrospective analysis of 23 cases of peripheral T2, N0, M0 carcinomas with microscopic pleural invasion on elastic stains and a matched control group documented a statistically significant (P = 0.0236) difference in survival between squamous cell carcinoma subgroups. This study therefore suggests the need for histologic assessment of peripheral lung carcinomas for invasion of internal pleural elastic lamina.

A fast communication aid for non-verbal subjects with severe motor handicaps

A computer-based communication system for non-verbal persons with severely deficient coordination of the upper extremities is described. The device doubles as an environmental control unit. Modular design is chosen throughout. Commercially available subunits are used to reduce cost. Input is by a 3 x 3 keyboard, when the user has some command over his hands. Otherwise a binary 'autoscan' access mode is used, which is controlled by repeated closures of a single binary switch. Output is in written form on a display or acoustical by synthesized speech. Hard-copy output can also be provided. Remote communication is possible by modem or by synthesized speech. Speed of message generation is increased by establishing a vocabulary, which contains, in addition to signs and letters of the alphabet, whole words and stereotyped phrases. The data blocks of the latter are accessed by a single input cycle similar to that used for the selection of isolated letters, symbols, etc.

Lipid granulomatosis: Erdheim-Chester disease

Twenty-six cases of lipid (cholesterol) granulomatosis, Erdheim-Chester Disease (ECD), have been described in the literature to date. A new case of ECD in a 33-year-old man with an unusual presentation of exudative ascites following a four year history of abdominal pain is reported. The radiographic and bone scan findings in this disease have been established and Ga-67 scan findings are reported. The Tc-99m sulphur colloid bone marrow and In-111 chloride scan findings are presented.

Are there any successful men from criminogenic backgrounds?

In the Cambridge Study in Delinquent Development, a prospective longitudinal survey of 411 London males, a vulnerable group of 63 boys from criminogenic backgrounds was defined on the basis of the best nonbehavioral predictors of delinquency at age 8-10 (low family income, large family size, convicted parents, low intelligence, and poor parental child-rearing behavior). These males were followed up to age 32, and the more successful men were defined according to criteria such as the absence of convictions and of other deviant behavior, good relationships with wives and children, and good accommodation and employment histories. Hence, "success" here refers to satisfactory social adjustment. The more successful men were those who had been neurotic at age 10, those who had few or no friends at age 8, those without convicted parents or behavior problem siblings, those with mothers who had a high opinion of their sons, and those who did not spend their leisure time with their fathers. At age 8-10 they were already better behaved and less daring than those later judged as the unsuccessful men. There was some tendency for shyness to act as a protective factor against delinquency for non-aggressive boys but as an aggravating factor for aggressive boys.

Prosthesis in velopharyngeal insufficiency: effect on nasal resonance

A review of case history records showed that 80 postoperative cleft palate cases with velopharyngeal incompetence and hypernasal voice quality had received speech therapy once or twice a week for unspecified periods of time but were unable to produce normal nasal resonance prior to the fitting of a nasopharyngeal prosthesis. After the fitting, 59 (74 percent) had normal nasal resonance during clinical assessment with an additional 10 showing reduced but residual hypernasality. It therefore is suggested that speech therapy may not be the treatment of choice in many cases of velopharyngeal inadequacy. Creation of what may be considered a relatively more normal speech mechanism by means of pharyngeal prosthesis seems to result in normal nasal resonance in a large majority of cases.

Synthesis of (6-3H)-1alpha-hydroxyvitamin D3 and its metabolism in vivo to (3H)-1alpha,25-dihydroxyvitamin D3

[6-3H]-1alpha-Hydroxyvitamin D3 was chemically synthesized and its full biological activity and radiochemical purity were demonstrated. With the use of this preparation it has been possible to demonstrate in vivo that in rats the [6-3H]-1Alpha-hydroxyvitamin D3 is converted to [6-3H]-1alpha,25-dihydroxyvitamin D3, the natural hormone. In fact, in the intestine and bone of rats given 32 picomoles of [6-3H]-1alpha-hydroxyvitamin D3 each day for 6 days, more than 80 percent of the lipid-soluble radioactivity exists as [6-3H]-1alpha,25-dihydroxyvitamin D3, a finding that suggests that much of the biological effectiveness of 1alpha-hydroxyvitamin D3 is due to its conversion to 1alpha,25-dihydroxyvitamin D3.