Canopy nitrogen, carbon assimilation, and albedo in temperate and boreal forests: Functional relations and potential climate feedbacks.

The availability of nitrogen represents a key constraint on carbon cycling in terrestrial ecosystems, and it is largely in this capacity that the role of N in the Earth's climate system has been considered. Despite this, few studies have included continuous variation in plant N status as a driver of broad-scale carbon cycle analyses. This is partly because of uncertainties in how leaf-level physiological relationships scale to whole ecosystems and because methods for regional to continental detection of plant N concentrations have yet to be developed. Here, we show that ecosystem CO(2) uptake capacity in temperate and boreal forests scales directly with whole-canopy N concentrations, mirroring a leaf-level trend that has been observed for woody plants worldwide. We further show that both CO(2) uptake capacity and canopy N concentration are strongly and positively correlated with shortwave surface albedo. These results suggest that N plays an additional, and overlooked, role in the climate system via its influence on vegetation reflectivity and shortwave surface energy exchange. We also demonstrate that much of the spatial variation in canopy N can be detected by using broad-band satellite sensors, offering a means through which these findings can be applied toward improved application of coupled carbon cycle-climate models.

An experimentally confirmed statistical model on arm movement.

The purpose of this research work was to develop a methodology to model arm movement in normal subjects and neurologically impaired individuals through the application of a statistical modelling method. Thirteen subjects with Parkinson's disease and 29 normal controls were recruited to participate in an arm motor task. An infrared optoelectronic kinematic movement analysis system was employed to record arm movement at 50 times per second. This study identified the modified extended Freundlich model as one that could be used to describe this task. Results showed that this model fit the data well and that it has a good correspondence between the observed and the predicted data. However, verification of the model showed that the residuals contained a sizeable autocorrelation factor. The Cochrane and Orcutt method was applied to remove this factor, which improved the fit of the model. Results showed that Parkinson's disease subjects had a higher autocorrelation coefficient than the normal subjects for this task. A positive correlation (r(s) = 0.72, p < 0.001) was found between the Langton-Hewer stage and the autocorrelation coefficient of PD subjects. This finding suggests that if autocorrelation is positively correlated with disease progression, clinicians in their clinical practice might use the autocorrelation value as a useful indicator to quantify the progression of a subjects' disease. Significant differences in model parameters were seen between normal and Parkinson's disease subjects. The use of such a model to represent and quantify movement patterns provides an important base for future study.

Attitudes of Hong Kong Chinese to traditional Chinese medicine and Western medicine: survey and cluster analysis.

OBJECTIVES: To determine whether within a cohort of Hong Kong out-patients definable subtypes exist based on their attitudes to traditional Chinese medicine and Western medicine. DESIGN: Data were collected using a structured questionnaire. SETTING: The sample of 503 subjects was recruited at two local outpatient clinics in Hong Kong. MAIN OUTCOME MEASURES: The study employs demographic variables, illness status, the Chinese-Western Medical Belief Scale, trust of physicians and subjects' preferences on consultation fees, attitude of health care professional, efficacy of service and waiting time during consultation. RESULTS: A cluster analysis yielded three clusters based on their attitudes towards traditional Chinese and Western medicine. One cluster, 24% of the sample, is noted for being older, poorer, more likely to be female and to have chronic conditions; they are sceptical of western physicians. The second cluster (63% of the sample) is younger and have considerably more belief in Western than traditional Chinese medicine. The third group (14%) is intermediate in age and is noted for a marked faith in both forms of medicine. CONCLUSIONS: A clear profile of these attitudes of Hong Kong Chinese may benefit health care professionals in making appropriate patient-doctor relationships and planning patient care.

Recent cocaine use is not associated with fetal acidemia or other manifestations of intrapartum fetal distress.

The objective of this paper is to evaluate the impact of recent cocaine use on umbilical cord blood gas values in cocaine-dependent pregnant women who received formal prenatal care. Ninety-two cocaine-dependent pregnant women receiving comprehensive prenatal care were divided into two groups, with patients in Group A (n = 35) testing positive for cocaine metabolites at the time of delivery and Group B (n = 57) testing negative. One hundred and three patients with no history of drug or alcohol dependence served as the control group (Group C). Umbilical cord blood gases were obtained at all deliveries. Additional variables included 1 and 5-min Apgar scores, meconium staining of the amniotic fluid, route of delivery, premature rupture of the membranes, and length of nursery stay. There were no statistically significant differences between groups in either umbilical artery pH, pO2, pCO2, bicarbonate, or base excess. Similarly, there was no difference in meconium staining of the amniotic fluid, depressed Apgar scores, cesarean delivery, or neonatal length of stay. Our data do not support an association between recent cocaine use and fetal hypoxemia or acidemia, depressed 5-min Apgar scores, meconium staining of the amniotic fluid, or cesarean delivery in cocaine-dependent pregnant women enrolled in prenatal care.

Perinatal complications associated with maternal tobacco use.

The use of tobacco products by pregnant women is associated with placenta previa, abruptio placentae, premature rupture of the membranes, preterm birth, intrauterine growth restriction and sudden infant death syndrome. Approximately 15-20% of women smoke during pregnancy. It has been suggested that smoking is responsible for 15% of all preterm births, 20-30% of all infants of low birthweight, and a 150% increase in overall perinatal mortality. Cigarette smoking is one of the most important and modifiable risk factors associated with adverse perinatal outcomes.

Comparison of Abbott LCx Chlamydia trachomatis assay with Gen-Probe PACE2 and culture.

In this study the LCx assay (a nucleic acid amplification assay) for Chlamydia trachomatis in endocervical samples was compared with the Gen-Probe PACE2 assay (a nucleic acid probe assay) for endocervical samples, and with endocervical culture. In addition, the efficacy of the LCx assay was determined for midstream clean-catch urine samples because it is often necessary to obtain such a sample for routine urine culture and it is simpler to collect only a single sample without also collecting a first-void urine for LCx. Endocervical specimens from 205 patients were tested for C. trachomatis via LCx and PACE2. Of these patients, 203 were tested by culture. Midstream clean-catch urine samples from 75 of these patients were tested by LCx. The sensitivities and specificities for these assays, after discrepant analysis, were 100 and 98.9% for LCx of endocervical samples, 52.4 and 100% for PACE2; and 71.4 and 100% for culture. The sensitivity/specificity of LCx for midstream clean-catch urines was 66.7/98.5%. The apparent prevalence of C. trachomatis in our population was 10.2%. These data indicate that among the methods tested, LCx of endocervical samples had the highest sensitivity for C. trachomatis in this population. The sensitivity of the urine LCx assay using midstream clean-catch collected urines was considerably less than that reported in other studies that used first-void urines but was higher than that of PACE2.

Criteria for same and different judgments and visual comparison strategies of four-year-olds.

4-year-olds made same and different judgments about pairs of stimuli requiring detailed comparison in 2 conditions: a judgment-only condition and a justification condition in which children explained the reasons for their judgments. The systematic comparison strategies revealed in the justifications indicated that all children had definite criteria for "same" and "different" although about two-thirds of the children used a criterion that differed from the adult criterion. Judgments were more accurate in the justification than in the judgment-only condition, suggesting that overt verbalizations and gestures may provide a beneficial external support for completion of a child's own visual comparison strategy.