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PubMed2000

Kinetics of nitrogen uptake by Populus tremuloides in relation to atmospheric CO(2) and soil nitrogen availability.

Sustained increases in plant production in response to elevated atmospheric carbon dioxide (CO(2)) concentration may be constrained by the availability of soil nitrogen (N). However, it is possible that plants will respond to N limitation at elevated CO(2) concentration by increasing the specific N uptake capacity of their roots. To explore this possibility, we examined the kinetics of (15)NH(4) (+) and (15)NO(3) (-) uptake by excised roots of Populus tremuloides Michx. grown in ambient and twice-ambient CO(2) concentrations, and in soils of low- and high-N availability. Elevated CO(2) concentration had no effect on either NH(4) (+) or NO(3) (-) uptake, whereas high-N availability decreased the capacity of roots to take up both NH(4) (+) and NO(3) (-). The maximal rate of NH(4) (+) uptake decreased from 12 to 8 &mgr;mol g(-1) h(-1), and K(m) increased from 49 to 162 &mgr;mol l(-1), from low to high soil N availability.Because NO(3) (-) uptake exhibited mixedkinetics over the concentration range we used (10-500 &mgr;mol l( -1)), it was not possible to calculate V(max) and K(m). Instead, we used an uptake rate of 100 &mgr;mol g(-1) h(-1) as our metric of NO(3) (-) uptake capacity, which averaged 0.45 and 0.23 &mgr;mol g(-1) h(-1) at low- and high-N availability, respectively. The proximal mechanisms for decreased N uptake capacity at high-N availability appeared to be an increase in fine-root carbohydrate status and a decrease in fine-root N concentration. Both NH(4) (+) and NO(3) (-) uptake were inversely related to fine-root N concentration, and positively related to fine-root total nonstructural carbohydrate concentration. We conclude that soil N availability, through its effects on fine-root N and carbohydrate status, has a much greater influence on the specific uptake capacity of P. tremuloides fine roots than elevated atmospheric CO(2). In elevated atmospheric CO(2), changes in N acquisition by P. tremuloides appeared to be driven by changes in root architecture and biomass, rather than by changes in the amount or activity of N-uptake enzymes.

Journal Article↗

PubMed2002

Responses of Acer negundo genders to interannual differences in water availability determined from carbon isotope ratios of tree ring cellulose.

Understanding the responses of riparian trees to water availability is critical for predicting the effects of changes in precipitation on riparian ecosystems. Dioecious Acer negundo L. (box elder) is a common riparian tree that is highly sensitive to water stress. Earlier studies indicated that the genders of A. negundo respond differently to water availability, with males being more conservative in their water use than females. To assess the potential effects of changes in precipitation on the sex ratio of riparian trees, we extended earlier studies of A. negundo by analyzing responses of male and female genotypes to interannual differences in water availability in a common garden. We measured growth of tree rings and used stable carbon isotope analysis of tree ring alpha-cellulose to integrate physiological responses to annual water treatments. During dry years, male and female trees exhibited similar growth and physiological responses. However, during wet years, females exhibited higher growth rates and lower carbon isotope ratios (indicating less conservative water use) than did males. Furthermore, we found that male trees exhibited similar stomatal behavior (inferred from integrated carbon isotope ratios) whether years were wet or dry, whereas females did not exhibit a consistent response to changes in water availability. We predict that with increasing precipitation and soil water availability, the representation of females will be favored because of shifts in the competitive interactions of the genders. Such changes may affect the reproductive output of these riparian trees and may influence overall water flux from riparian ecosystems. In addition, this study demonstrates the utility of carbon isotope analysis for assessing long-term responses of tree populations to shifts in water availability.

Acer↗

PubMed1998

Tissue availability of insulin-like growth factor I is inversely related to insulin resistance in essential hypertension: effects of angiotensin converting enzyme inhibition.

BACKGROUND: The insulin-like growth factor I possesses biologic actions that resemble those of insulin. Tissue access of the factor depends on the distribution of the circulating bound factor between its binding protein 3 that remains within the intravascular space and its binding protein I that is able to cross the endothelium. Preliminary results have shown that tissue availability of insulin-like growth factor I is a determinant of glucose regulation in essential hypertension OBJECTIVE: To investigate whether the tissue availability of circulating insulin-like growth factor I in patients with essential hypertension is related to insulin resistance and whether chronic angiotensin converting enzyme inhibition influences tissue availability of the factor and insulin resistance in these patients. DESIGN AND METHODS: We studied 29 patients with essential hypertension and 20 age-matched and sex-matched normotensive subjects. The measurements were repeated for 25 patients after 12 months of treatment with lisinopril. Tissue availability of circulating insulin-like growth factor I was assessed by analyzing its distribution between its binding proteins 3 and 1. An insulin resistance index was estimated using the homeostasis model analysis of fasting insulin-glucose interactions. Levels of serum insulin-like growth factor I binding proteins 3 and 1, plasma insulin-like growth factor I, and insulin were determined by specific radioimmunoassays. RESULTS: Baseline insulin resistance index was significantly higher in the hypertensive patients than it was in the normotensive controls. With the upper 100% confidence limit of the normotensive population as the cutoff point, a subgroup of 12 hypertensives had an abnormally high insulin resistance index. Compared with patients with normal insulin resistance indexes, patients with greater than normal indexes were characterized by lower binding protein 1 levels, similar binding protein 3 levels, lower binding protein 1 : binding protein 3 ratio and similar insulin-like growth factor I levels. The serum binding protein 1 level and the binding protein 1 : binding protein 3 ratio were inversely correlated to the insulin resistance index for the whole group of hypertensives. After treatment with lisinopril hypertensive patients with higher than normal insulin resistance indexes at baseline exhibited normalization of this parameter and significant increases of binding protein 1 levels and binding protein 1 : binding protein 3 ratio, with no significant changes in insulin-like growth factor I levels. These parameters remained unchanged for the remaining patients. CONCLUSIONS: These results suggest that tissue availability of circulating insulin-like growth factor I is a determinant of insulin sensitivity in patients with essential hypertension. Whereas the patients with normal insulin sensitivity exhibit greater than normal tissue access of circulating insulin-like growth factor I, patients with insulin resistance present normal tissue access of the factor. Our findings suggest that the ability of angiotensin converting enzyme inhibitors to restore insulin sensitivity in essential hypertensives may be related to their ability to facilitate the tissue availability of circulating insulin-like growth factor I.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed1996

The benefits and risks of over-the-counter availability of nicotine polacrilex ("nicotine gum").

Nicotine polacrilex ("nicotine gum") is effective in helping persons to quit smoking cigarettes. Because many persons try to quit without formal assistance, it may be an appropriate product for over-the-counter (OTC) purchase. Some smokers, however, might use such a product in lieu of more effective methods of cessation, and still others might use it to cope with enforced periods of nicotine abstinence (eg, at the work place) and thereby delay their decision to quit. The study's objective was to assess the public health benefits and risks of OTC availability of nicotine gum. A Markov model was developed and used to contrast two alternative policy scenarios: one in which nicotine gum was assumed to remain available only by prescription, and another in which it was assumed to be made available for OTC purchase. Various data sources were used to estimate the model, including the Health Promotion and Disease Prevention Supplement to the 1991 National Health Interview Survey and the 1986 Adult Use of Tobacco Survey. Primary outcome measures included the numbers of persons who would try to quit smoking, the numbers who would use various methods of smoking cessation, including OTC nicotine gum, and the numbers of current adult smokers who would be abstinent at the end of 10 years. Findings suggest that an average of 3 million persons each year would use OTC nicotine gum. As a consequence of OTC availability, an additional 450,000 smokers would be abstinent at the end of 10 years. These results are sensitive to assumptions regarding the effectiveness of OTC nicotine gum, as well as to the effect of OTC availability on the use of other methods of smoking cessation. The number of persons who would quit smoking, however, increases under a fairly wide range of assumptions. Over-the-counter availability of nicotine gum may confer significant public health benefits.

Adolescent↗

PubMed2001

Adjustment of offspring sex ratios in relation to the availability of resources for philopatric offspring in the common brushtail possum.

The local-resource-competition hypothesis predicts that where philopatric offspring compete for resources with their mothers, offspring sex ratios will be biased in favour of the dispersing sex. This should produce variation in sex ratios between populations in relation to differences in the availability of resources for philopatric offspring. However, previous tests of local resource competition in mammals have used indirect measures of resource availability and have focused on sex-ratio variation between species or individuals rather than between local populations. Here, we show that the availability of den sites predicts the offspring sex ratio in populations of the common brushtail possum. Female possums defend access to dens, and daughters, but not sons, occupy dens within their mother's range. However, the abundances of possums in our study areas were determined principally by food availability. Consequently, in food-rich areas with a high population density, the per-capita availability of dens was low, and the cost of having a daughter should have been high. This cost was positively correlated with male bias in the sex ratio at birth. Low per capita availability of dens was correlated with male bias in the sex ratio at birth.

Animals↗

PubMed1994

Patterns of autologous blood use in elective orthopedic surgery: does the availability of autologous blood change transfusion behavior?

We studied the orthopedic surgery service at our institution to determine whether the mere availability of autologous blood (AB) affected transfusion practice. As a group, patients who had AB available received an average of 1.11 fewer red cell units per hospitalization than did patients with only homologous blood (HB) available. At every transfusion episode, those patients having AB available received fewer red cell units than did patients without AB available. Predeposit of autologous red cells was effective in protecting 77.6% of patients from HB exposure. The availability of autologous red cells resulted in an overall more conservative approach to transfusion.

Aged↗

PubMed2005

Effect on enamel microhardness of two consumer-available bleaching solutions when compared with a dentist-prescribed, home-applied bleaching solution and a control.

BACKGROUND: There exists limited data in the literature regarding the efficacy and safety of consumer-available, paint-on bleaching solutions. PURPOSE: The purpose of this in vitro study was to evaluate the effect of two consumer-available, paint-on bleaching products on enamel microhardness against a control and a dentist-prescribed, home-applied (DPHA) bleaching product. MATERIALS AND METHODS: Eighty enamel slabs were obtained from extracted human teeth and randomly divided into four treatment groups: (1) control; (2) Opalescence (Ultradent Products, Inc., South Jordan, UT, USA); (3) Crest Night Effects (Procter & Gamble, Cincinnati, OH, USA); and (4) Colgate Simply White Night (Colgate-Palmolive Co., Piscataway, NJ, USA). Opalescence is a carbamide peroxide DPHA product, whereas Crest Night Effects and Colgate Simply White Night are consumer-available products. The specimens in groups 2 to 4 underwent 2 weeks of treatment for 8 h/d. Specimens were maintained in artificial saliva at 37 degrees C between treatments. Subsequently, one-half of the specimens in groups 2 to 4 (n=10) underwent an additional seven treatments for 8 h/d, while the other half were stored in artificial saliva, receiving no further treatment. Microhardness was measured as Knoop hardness numbers (KHNs) at baseline and after 1, 7, 14, and 21 treatment days. The results were analyzed for statistical significance both intra- and intergroups using analysis of variance (p=.05). RESULTS: A statistically significant reduction in mean KHN was observed compared with baseline at 1, 7, 14, and 21 treatment days for group 4 and at 7 treatment days for group 3. When compared with the control or DPHA product, group 4 was the only treatment that resulted in significantly lower mean KHNs at 7, 14, and 21 treatment days. CONCLUSION: When evaluating enamel microhardness, consumer available, paint-on bleaching solutions may adversely affect enamel microhardness compared to a control and 10% carbamide peroxide DPHA bleaching solution. CLINICAL SIGNIFICANCE: With numerous consumer-available bleaching products on the market, it is crucial to be judicious in their selection and use. The results of this in vitro study showed that the consumer-available, paint-on bleaching solutions adversely affected enamel microhardness at some time during the study. Consumers should be made aware of this effect on enamel.

Carbamide Peroxide↗

PubMed2006

Urban-rural differences in the availability of hospital information technology applications: a survey of Georgia hospitals.

CONTEXT: Information technology (IT) has been identified as a potential tool for improving the safety of health care delivery. PURPOSE: To determine if there are significant differences between urban and rural community hospitals in the availability of selected IT functional applications and technological devices. METHODS: A mailed survey of community hospitals in Georgia assessing the current availability of IT applications (54.6% response rate). FINDINGS: Georgia hospitals reported having 63.6% of 56 possible functional applications computerized but only 52.9% of 41 technological devices. Compared to rural hospitals, urban hospitals had significantly more functional applications computerized (38.0 vs 31.8, P = .031) and technological devices available (23.9 vs 18.2, P = .016). Urban hospitals had significantly (P < .05) more IT applications available in 4 areas: emergency room services (7 of 10), surgical/operating room (8 of 12), laboratory (7 of 12), and radiology (5 of 11). Overall, the availability of IT applications was bimodal in rural hospitals: over 40% of rural hospitals had adopted over 70% of all applications, while approximately 26% of rural hospitals had adopted less than 30%. CONCLUSIONS: Some of the observed urban/rural differences in availability of IT applications may be due to differences in the scope of services provided by rural hospitals, in particular laboratories, radiology departments, emergency rooms, and surgery/operating rooms. Nevertheless, the bimodal distribution of IT applications adopted in rural hospitals raises concerns about the ability of selected rural hospitals to take advantage of regional data-sharing initiatives and maintain quality of patient care in the future.

Georgia↗

PubMed1975

Alterations in hepatic chromatin template availability during infection.

Hepatic chromatin was isolated from rats at various times after inoculation with either live or heat-killed bacteria. The chromatin was assayed under conditions that allow determination of the DNA template available to support in vitro transcription. Both a fulminant Diplococcus pneumoniae and a milder Salmonella typhimurium infection produced time-related increases in hepatic chromatin template availability when compared to chromatin isolated from rats inoculated with heat-killed bacteria. Both timing and magnitude of increased template availability correlated with the severity of the infection. The earliest change observed was a 50 percent rise in availability noted 4 h after inoculation with D. pneumoniae. This preceded the onset of fever, as well as other known heaptic consequences of systemic infection. After 24 h of infection the maximum rise of 90 percent occurred. Similar changes developed during S. typhimurium infection, but were slower in onset and smaller in magnitude. Adrenalectomy prior to infection enhanced the severity of the disease but markedly blunted the increase in template availability. The data are consistent with the hypothesis that systemic infection regulates the hepatic metabolic response to infection through transcriptional control and that a permissive or stimulatory action of glucocorticoids is involved in the increases in template availability effected.

Adrenalectomy↗

PubMed1998

Low energy availability, not stress of exercise, alters LH pulsatility in exercising women.

We tested two hypotheses about the disruption of luteinizing hormone (LH) pulsatility in exercising women by assaying LH in blood samples drawn at 10-min intervals over 24 h from nine young, habitually sedentary, regularly menstruating women on days 8, 9, or 10 of two menstrual cycles after 4 days of intense exercise [E = 30 kcal.kg lean body mass (LBM)-1.day-1 at 70% of aerobic capacity]. To test the hypothesis that LH pulsatility is disrupted by low energy availability, we controlled the subjects' dietary energy intakes (I) to set their energy availabilities (A = I - E) at 45 and 10 kcal.kg LBM-1.day-1 during the two trials. To test the hypothesis that LH pulsatility is disrupted by the stress of exercise, we compared the resulting LH pulsatilities to those previously reported in women with similar controlled energy availability who had not exercised. In the exercising women, low energy availability reduced LH pulse frequency by 10% (P < 0.01) during the waking hours and increased LH pulse amplitude by 36% (P = 0.05) during waking and sleeping hours, but this reduction in LH pulse frequency was blunted by 60% (P = 0.03) compared with that in the previously studied nonexercising women whose low energy availability was caused by dietary restriction. The stress of exercise neither reduced LH pulse frequency nor increased LH pulse amplitude (all P > 0.4). During exercise, the proportion of energy derived from carbohydrate oxidation was reduced from 73% while A = 45 kcal.kg LBM-1.day-1 to 49% while A = 10 kcal.kg LBM-1.day-1 (P < 0.0001). These results contradict the hypothesis that LH pulsatility is disrupted by exercise stress and suggest that LH pulsatility in women depends on energy availability.

Adolescent↗

PubMed2000

North Carolina stroke prevention and treatment facilities survey. Statewide availability of programs and services.

BACKGROUND/PURPOSE: The aim of this study was to determine the statewide availability of facilities and programs for stroke prevention and treatment to identify underserved regions and target educational efforts. METHODS: A single-page survey was mailed to the directors of each inpatient medical facility in North Carolina. Data collected included the availability of selected diagnostic tests, programs, and services. Facilities were categorized as providing basic (emergency department, brain CT, treatment with rtPA, transthoracic echocardiography, carotid ultrasonography, cerebral angiography, carotid endarterectomy) or advanced (basic services plus brain MRI, MR angiography, transesophageal echocardiography, transcranial Doppler ultrasonography, interventional radiology) services. The availability of other programs and services, including having a neurologist on staff, organized anticoagulation clinics, inpatient rehabilitative services, diffusion-weighted MRI, community awareness and rapid stroke identification programs, stroke teams, stroke acute care units or an equivalent, and the use of stroke-care maps, were also determined. RESULTS: Complete responses were obtained from all of the state's 125 inpatient medical facilities. Overall, 97% of the state's population resided in counties with a hospital providing at least some stroke prevention or treatment procedures or services. Full basic services were provided by 23 facilities located in 19 of the state's 100 counties and were available to 52% of the state's population based on county of residence; advanced services were provided by 8 facilities located in 7 counties and were available to 26% of the state's population based on county of residence. Stroke-care maps were used in 83% of basic or advanced centers versus 23% of other hospitals (P<0.001), stroke teams were organized in 48% versus 12% (P=0.001), stroke units or equivalents were available in 61% versus 9% (P<0.001), rapid patient identification programs were in place in 57% versus 9% (P<0.001), and community awareness programs were in place in 57% versus 21% (P=0.005). CONCLUSIONS: Only 52% of the state's population reside in counties with hospitals providing full basic services; by expanding these services to only 6 additional facilities and thereby encompassing the state's 50 most populous counties, this proportion would be increased to 84%. Services that may improve outcomes and reduce costs (eg, stroke teams, stroke units, care maps) are not widely used, even in centers with full basic capabilities. Targeting educational efforts to these centers could improve the overall level of stroke care for the majority of the state's population. The study serves as a model that can be applied to other states and regions.

Data Collection↗

PubMedDate not supplied

The prevalence of cancer: a review of the available data.

AIMS AND BACKGROUND: Cancer prevalence in a population, defined as the proportion - or the number - of people who were diagnosed with a cancer during their lives and are still alive at a given date, is a crucial indicator for heath care planning and resource allocation. Long-term population-based cancer registries (CR) are the appropriate tools to produce prevalence figures, which, however, are scarcely available. This paper contains a review up to 1999 of the published data world-wide (reports and articles) on cancer prevalence: including measured and estimated figures. MATERIALS AND METHODS: Data on cancer prevalence from CRs are available for the Nordic countries, Connecticut, and Italy. In addition, electronic data are available for the European Union (EU). Data for the Nordic countries were first published in the mid-seventies, reporting the prevalence for 1970. The first data from Connecticut were available 10 years later. Estimates for all EU countries were published by the International Agency for Research on Cancer (IARC) in 1997. In Italy, observed and estimated data on the prevalence of respiratory and digestive tract cancer and breast cancer have been published during the nineties, followed by a systematic analysis for all cancers in 1999. By using information obtained from CRs, cancer prevalence data were calculated directly (observed prevalence) by means of incidence and follow-up information on individual cancer patients, or indirectly (estimated prevalence) by means of mathematical models, which generally use epidemiological information at the aggregate level. RESULTS: Cancer prevalence for all cancers combined (proportions per 100,000 inhabitants) showed values of less than 700 in males and less than 800 in females in 1970 (Finland) to over 2,300 in males and over 3,000 in females in 1992 (Italian registries). With few exceptions, in each country and period considered the cancer sites contributing most to cancer prevalence are lung, colon-rectum, prostate and bladder in males, colon-rectum, breast, uterus (both cervix and corpus) and ovary in females. At present, comparison of measurements from different areas is difficult because there exists no standardized mode of presentation. CONCLUSIONS: In spite of their being potentially useful for health care planning, prevalence data have been produced inconsistently and late by cancer registries, at least in comparison with the systematic availability of incidence and survival statistics. The available data can be compared only to a limited extent due to differences in completeness, in the choice of indicators, in the standard populations, and in the frequency of publication. It would be desirable that in the future data will be produced systematically, with a higher level of standardization compared to the past, and, most importantly, on the same geographic and administrative scale as health-care decision-making.

Europe↗

PubMed2005

Agreement between diagnoses reached by clinical examination and available reference standards: a prospective study of 216 patients with lumbopelvic pain.

BACKGROUND: The tissue origin of low back pain (LBP) or referred lower extremity symptoms (LES) may be identified in about 70% of cases using advanced imaging, discography and facet or sacroiliac joint blocks. These techniques are invasive and availability varies. A clinical examination is non-invasive and widely available but its validity is questioned. Diagnostic studies usually examine single tests in relation to single reference standards, yet in clinical practice, clinicians use multiple tests and select from a range of possible diagnoses. There is a need for studies that evaluate the diagnostic performance of clinical diagnoses against available reference standards. METHODS: We compared blinded clinical diagnoses with diagnoses based on available reference standards for known causes of LBP or LES such as discography, facet, sacroiliac or hip joint blocks, epidurals injections, advanced imaging studies or any combination of these tests. A prospective, blinded validity design was employed. Physiotherapists examined consecutive patients with chronic lumbopelvic pain and/or referred LES scheduled to receive the reference standard examinations. When diagnoses were in complete agreement regardless of complexity, "exact" agreement was recorded. When the clinical diagnosis was included within the reference standard diagnoses, "clinical agreement" was recorded. The proportional chance criterion (PCC) statistic was used to estimate agreement on multiple diagnostic possibilities because it accounts for the prevalence of individual categories in the sample. The kappa statistic was used to estimate agreement on six pathoanatomic diagnoses. RESULTS: In a sample of chronic LBP patients (n = 216) with high levels of disability and distress, 67% received a patho-anatomic diagnosis based on available reference standards, and 10% had more than one tissue origin of pain identified. For 27 diagnostic categories and combinations, chance clinical agreement (PCC) was estimated at 13%. "Exact" agreement between clinical and reference standard diagnoses was 32% and "clinical agreement" 51%. For six pathoanatomic categories (disc, facet joint, sacroiliac joint, hip joint, nerve root and spinal stenosis), PCC was 33% with actual agreement 56%. There was no overlap of 95% confidence intervals on any comparison. Diagnostic agreement on the six most common patho-anatomic categories produced a kappa of 0.31. CONCLUSION: Clinical diagnoses agree with reference standards diagnoses more often than chance. Using available reference standards, most patients can have a tissue source of pain identified.

Humans↗

PubMed2005

Do Indonesian medical practitioners approve the availability of emergency contraception over-the-counter? A survey of general practitioners and obstetricians in Jakarta.

BACKGROUND: Few studies have examined the attitude of medical practitioners towards the availability of emergency contraception (EC) without prescription. In Indonesia, EC (either Yuzpe regimen or Postinor-2) is available by prescription only. We aimed to examine the level of knowledge, attitudes and practices of medical practitioners in Indonesia about EC, in particular their attitudes to the availability of EC over-the-counter (OTC), using a questionnaire. METHODS: Data were collected by an anonymous structured questionnaire. Questionnaires were distributed to general practitioners in 36 Community Health Centres and 25 private clinics using stratified random sampling according to area in Jakarta, and to obstetricians practicising in 24 government and private hospitals and eight private clinics in Jakarta. Two hundred and five general practitioners and 142 obstetricians and gynaecologists participated; overall response rate was 75%. RESULTS: Although most participants were familiar with EC, only 22% received a very good knowledge score (4 or 5/5 answers correct), while 52% received a poor score (0-2/5 correct). Most participants did not support the OTC availability of EC (70%). Logistic regression identified that participants who prescribed EC had an Odds of 3.8 (95% CI 1.90, 7.73) of approving OTC EC, after adjustment for age and speciality. CONCLUSION: Although many organisations are working towards OTC availability of EC, it needs to be recognized and addressed that doctors who do not prescribe EC are unlikely to support the increased availability of EC.

Journal Article↗

PubMed2000

Availability bias in clinical formulation: the first idea that comes to mind.

This study tested whether initial client formulations are based simply on the ideas that come most readily to mind, irrespective of the validity of these ideas. This phenomenon is known in decision theory literature as availability bias. The study tested the influence of two possible sources of availability bias in formulation: (a) theoretical orientation; and (b) a suggestion in a referral letter. Forty-four qualified and 20 trainee clinical psychologists participated in a procedure designed to reflect clinical practice. Clinical materials consisted of a fictional referral letter describing a client with adult attachment difficulties and post-traumatic stress disorder. Participants recalled information from the referral letter, described their areas of further interest and initial hypotheses. Results showed no evidence of an availability bias in clinical formulation as a result of theoretical orientation. Theoretical orientation towards attachment did appear to influence the availability of attachment ideas and predicted clinicians taking a stronger attachment focus when discussing the client. In particular, a self-report measure of theoretical orientation demonstrated high predictive validity. However, orientation towards attachment did not predict bias in the sense of selective recall of attachment information or neglect of alternative psychological frameworks. The study provided an inadequate test of availability bias as a result of a suggestion in the referral letter, possibly due to a ceiling effect, and no conclusions can be drawn as to clinical materials as a potential source of availability bias. The discussion addresses implications for further research and for a scientist-practitioner approach to individual case formulation.

Adult↗

PubMed2001

Availability of child care in the United States: a description and analysis of data sources.

Lack of high-quality, affordable, and accessible child care is an often-cited impediment to a manageable balance between work and family. Researchers, however, have been restricted by a scarcity of data on the availability of child care across all U.S. communities. In this paper we describe and evaluate several indicators of child care availability that have been released by the U.S. Census Bureau over the last 15 years. Using community- and individual-level analyses, we find that these data sources are useful for indicating child care availability within communities, even though they were collected for other purposes. Furthermore, our results generally suggest that the data on child care availability are equally valid across communities of different urbanicity and average income levels, although it appears that larger geographic areas more accurately capture the child care market of centers than that of family day care providers. Our analyses indicate that center child care is least available in nonmetropolitan, poor communities, and that family day care is most available in nonmetropolitan, mixed-income communities. We discuss the benefits and limitations of the data sources, and point to directions for future data developments and research.

Child↗

PubMed1984

Corticosterone availability in male rats at rest and during shock avoidance: differences among individuals, temporal patterns and effects of dexamethasone.

Repeated measurement of the time-integral of interstitial fluid free corticosterone concentration (corticosterone availability) under home-cage conditions, during exposure to recently unfamiliar apparatus, and during active shock avoidance over 3 days, demonstrated extreme stability within individuals, and consistent differences among individuals, in corticosterone availability under home-cage conditions. These consistent differences among individuals were preserved, while mean levels were doubled, during exposure to apparatus and during shock avoidance after treatment with dexamethasone. However, this persistent pattern of differences among individuals was not apparent during shock avoidance in the absence of dexamethasone. Shock avoidance provoked up to fourfold increases in corticosterone availability. Repeated measurements over 3 days showed consistent hour-to-hour increases within days and a gradual decline over days. Dexamethasone given 4 h before shock avoidance resulted in corticosterone availability intermediate between that in home-cage and that in the previous shock-avoidance session. The situation-dependent loss of consistent interindividual differences is proposed to signal a qualitative change in regulation of corticosterone availability within individuals, and a tactic for using inter-individual differences to study some aspects of complex regulatory systems is suggested. The hour-to-hour increase in corticosterone availability during shock avoidance may be attributable to slow achievement of full adrenal output; the decline over days may be due to behavioural factors.

Animals↗

PubMed1994

A behavioral economic analysis of concurrently available money and cigarettes.

In economic terms, consumption of a reinforcer is determined by its price and the availability and price of other reinforcers. This study examined the effects of response-requirement (i.e., price) manipulations on the self-administration of two concurrently available reinforcers. Six cigarette smokers participated in 4-hr sessions in which money and puffs on a cigarette were concurrently available according to fixed-ratio schedules of reinforcement. Once stable responding was obtained with both reinforcers available at Fixed Ratio 100, the response requirement for one reinforcer was systematically varied (Fixed Ratio 1,000 and 2,500), while the other reinforcer remained scheduled at Fixed Ratio 100. Increasing the fixed-ratio size for a reinforcer decreased its consumption, with a greater decrease occurring for monetary reinforcement. This finding was quantified in economic terms as own-price elasticity, with elasticity coefficients greater for money than cigarettes. The effects of fixed-ratio size on response output also differed across the two reinforcers. Although greater responding occurred for money at Fixed Ratio 100, increases in fixed-ratio size (for money) decreased responding for money, whereas the same increase in fixed-ratio size (for puffs) increased responding for puffs. Finally, increasing the fixed-ratio size for one reinforcer had little effect on consumption of the other concurrently available reinforcer. This finding was quantified as cross-price elasticity, with elasticity coefficients near 0.0 for most subjects, indicating little or no reinforcer interaction. The results indicate that the reinforcing effects of cigarettes and money in the setting studied here differed, and that the effects produced by changing the price of one reinforcer did not interact with the consumption of the other concurrently available reinforcer.

Adolescent↗