bluuebunny/crossref_metadata_2025 huggingface dataset:
Cerebrospinal Fluid‐Contacting Area of the Deep Pineal: Effects of Photoperiod
Authors: Welsh Marcia G. , Sheridan Michael N. , Rollag Mark D.
Published: February 2007

The surface of the pineal recess of the Syrian hamster demonstrates three morphologically distinct zones that are classified as the peripheral, transitional, and central zones. The central zone is the most remarkable because of the number of distinguishable morphological specializations in this region that appear to indicate interaction between the cerebrospinal fluid (CSF) and associated ventricular structures and the deep pineal gland. CSF‐contacting pinealocytes are present in the central zone and have a relatively indistinct ventricular surface except for the presence of surface blebs and pinealocyte processes that course on the surface of the deep pineal. Supraependy‐mal neurons and neuronal processes appear to converge on the central zone, occasionally having presumptive terminals that are associated with the cells of the central zone. When the hamsters were maintained in a short photoperiod (LD 8: 16), the CSF‐contacting area of the pineal recess was significantly larger in those hamsters killed 2 hours before lights off compared to those killed 2 hours before lights on (P < 0.01). There were no significant differences in the CSF‐contacting area when comparing two groups of hamsters maintained in a long photoperiod (LD 14: 10, killed 2 hours before lights on and lights off, respectively). There was statistically significant interaction (P < 0.05) between the lighting cycle and the time of day of death on the appearance of CSF‐contacting pinealocytes. The hamsters maintained in LD 8: 16 had significantly reduced testicular weights when compared to those maintained in LD 14: 10. The plasticity of the central zone and the associated CSF‐contacting pinealocytes of the pineal recess of the hamster are evidence that this region demonstrates morphological changes that are dependent upon the physiological state of the animal.
Effects of Melatonin on the Growth of MtT/F4 Anterior Pituitary Tumor
Authors: Chatterjee Shilla , Banerji Tapan K.
Published: February 2007

In the present report, we have examined the anti‐tumor potential of melatonin by utilizing the MtT/F4 anterior pituitary transplantable tumor. The tumor was obtained (Bogden Labs.) in cryopreserved condition and transplanted (in the left rear thigh), and allowed to grow for 8 weeks in adult Fischer 344 rats, maintained under uniform laboratory conditions of light (LD 14: 10; lights on at 06: 00 h), and temperature (21–23°C). Subsequently, the tumor was dissected out, minced, and washed in Medium 199, and similarly transplanted into groups of adult Fischer 344 rats representing the final tumor recipient groups utilized for die evaluation of melatonin's anti‐tumor effects. Melatonin (50 μg/0.1 ml/animal) was administered subcuta‐neously either early in the morning (at 08: 00 h), or late in the afternoon (at 18: 00 h), for 6 weeks, beginning the day after tumor transplantation. The matched controls were given equal volumes of physiological saline. A careful record of the appearance and growth of the tumor was maintained by examining the animals every morning. At the termination of the experimental schedule, the tumor masses were carefully dissected out, rinsed with normal saline, dried, and weighed on a sensitive Mettler balance. Our results showed that melatonin significantly increased the latency period of the tumor, irrespective of the time of drug administration. Analysis of the final tumor weights showed that afternoon, but not morning, injections of melatonin significandy reduced body the absolute (P<0.025) and relative (P<0.05) tumor weights in comparison to the saline‐injected matched control. These results suggest that a) melatonin exhibits its anti‐tumor efficacy on MtT/F4 tumor, by delaying the appearance of the tumor, and b) the anti‐tumor potential of melatonin is greatly dependent on the time of administration of die drug within the daily light‐dark cycle.
Stimulation of Serotonin‐N‐Acetyltransferase Activity in the Pineal Gland of the Mongolian Gerbil (Meriones unguiculatus) by Intracerebroventricular Injection of Vasoactive Intestinal Polypeptide
Authors: Schröder Hannsjörg , Stehle Jörg , Møller Morten
Published: February 2007

There is ever‐increasing evidence that intrapineal peptides have an important role in the modulation of pineal melatonin synthesis. In the pineal gland of the Mongolian gerbil (Meriones unguiculatus), we have previously shown the presence of VIP‐immunoreactive nerve fibers as well as pinealocytic VIP receptors. To assess the functional significance of these findings, 10 μl of a 1 μM or 1 nM solution of VIP were injected into the lateral ventricle of gerbils over a period of 10 min. Animals were killed 1.5 hr after injection, and the superficial pineal glands were excised and assayed for N‐acetyltransferase (NAT) activity. Injection of the 1 μM VIP solution stimulated the NAT activity to values four times the control values. The results are compatible with an in vivo influence on the pineal gland indole metabolism of the nonsympathetic VIP‐containing nerve fibers via VIP‐receptors present in the gland.
Comparisons of Sizes of Pinealocyte Nuclei and Pinealocytes in Young and Adult Chinese Hamsters (Cricetulus griseus) Under Different Photoperiod Conditions
Authors: Hira Yoshiki , Sakai Yuko , Matsushima Shoji
Published: February 2007

Semiquantitative electron microscopic observations on pinealocytes of the Chinese hamster (Cricetulus griseus) were made to compare the sizes of pinealocyte nuclei and pinealocytes as a whole, their nuclei and cytoplasm together, over a 24‐hr period, between young animals (60‐70 days old) and adult animals (120–130 days old) under LD 12: 12 and between adults under LD 12: 12 and LD 14: 10. Under LD 12: 12, similar 24‐hr rhythms exist in the nuclear area and the area of pinealocytes of young animals, whereas in adults these values exhibit no significant 24‐hr rhythm. In adults under LD 14: 10, there is no significant 24‐hr rhythm in the nuclear area, but the area of pinealocytes shows a statistically significant 24‐hr rhythm. Thus, in the Chinese hamster, the relationships between nuclear area and area of pinealocytes with time of day vary, depending on the age of animals as well as different photoperiodic conditions, although they differ only slightly.
Close microtopographical relationships between sympathetic nerve terminals and bulbous process endings of pinealocytes in the pineal gland of the Mongolian gerbil
Authors: Redecker Peter
Published: February 2007

Abstract: Previous studies have shown that pinealocytes of the gerbil pineal gland exhibit processes that form terminal swellings filled with abundant electron‐lucent microvesicles. The membrane of these presumptive secretory microvesicles is known to contain synaptophysin, a major integral glycoprotein of neuronal synaptic vesicles. The present study was conducted to evaluate the microtopographical relationships between the vesicle‐rich process swellings and intra‐pineal nerve terminals. For this purpose, both nerve terminals and pinealocyte process endings were visualized immunohistochemically in the same semi‐thin sections of plastic‐embedded gerbil pineals, using antibodies directed against synaptophysin. This approach consistently revealed close spatial associations of punctate immunopositive nerve endings with intensely stained bulbous process terminals of pinealocytes in or near the perivascular spaces. The light‐microscopic observations of intimate neuronal‐pinealocytic relationships were corroborated at the electron‐microscopic level. Perivascular varicosities with ultrastructural features characteristic of sympathetic nerve terminals were frequently juxtaposed to vesicle‐filled process endings of pinealocytes. Analysis of serial thin sections showed that multiple point‐to‐point contacts are encountered between noradrenergic nerve terminals and pinealocytic process swellings. Our morphological findings imply that bulbous process terminals, at least in the gerbil pineal gland, are major targets for the neuronal control of the secretory activity of pinealocytes.
Non‐invasive electrical measurements for the evaluation of the hydration state of the skin: comparison between three conventional instruments ‐ the Comeometer®, the Skicon® and the Nova DPM®
Authors: Clarys Peter , Barel André O. , Gabard B.
Published: February 2007

Background/aims:

Some electrical properties of the skin may be related to the water content of the horny layer, and measurements of impedance and/or capacitance have been used to assess the hydration state of the skin surface. This study was designed to compare three commercially available instruments used in dermato‐cosmetic research, namely, the Corneometer CM 825, the Nova DPM 9003 and the Skicon‐200.

Methods:

Comparative measurements were carried out with the three instruments in vivo on the volar part of the forearms of 12 human volunteers.

Results:

The decrease in hydration induced by an irritant cationic detergent, and the increase of hydration after application of a moisturizer cream under occlusion could be easily measured with the three instruments. High degrees of correlation were obsewed between the three instruments over a broad range of hydration values of the skin.

Conclusions:

This comparative study performed under controlled environmental conditions reveals that the three instruments give validated coherent information concerning relative changes in hydration of the upper layers of the epidermis.
Consumer perception of sensitive hands: what is behind it?
Authors: Paye M. , Dalimier Ch. , Cartiaux Y. , Chabassol C.
Published: February 2007

Background/aims:

Sensitive skin is a regular matter of complaint from consumers. Skin being physiologically and historically different on different body parts, this study aims at characterizing hand skin from a population of subjects complaining of sensitive hands.

Methods: A

survey was performed on a panel of 150 women. One‐third claimed to have “sensitive hands”. Their hand skin condition was compared to those claiming to have “non‐sensitive hands” by means of a self‐evaluation questionnaire, clinical examination (erythema, dryness), instrumental measurements (reflectance spectrometry, evaporimetry, skin surface capacitance and biomechanic properties measurements) and analysis of stratum corneum tape stripping. The two groups were also compared for their ability to perceive differences in the feel of consumer products on their hands.

Results:

“Sensitive hands” subjects perceived their hands as being dry and irritated. Such subjective perceptions were confirmed by visual assessment of erythema, capacitance measurement and stratum corneum stripping analysis. There was no correlation between the perception of sensitive hands and the ability of better perceiving the feel on skin of everyday products.

Conclusion:

Sensitive hands perception is a reality sustained by measurable skin condition changes. It merits to be further investigated and should be taken into account.
Time‐dependent changes in dermal peeling force of adhesive tapes
Authors: Tokumura F. , Ohyama K. , Fujisawa H. , Suzuki M. , Nukatsuka H.
Published: February 2007

Background/aims:

The dermal peeling force of acrylic adhesive tapes was evaluated in relation to the accumulation of fluid and the number of stripped corneocytes.

Methods:

Two kinds of tapes that had different water vapor permeability were applied on the flexor side of both forearms in eight healthy male volunteers. The dermal peeling force was measured at 1, 4, 8 and 24 h after application of the tapes. Simultaneously, the electrical conductance of the skin beneath the applied tape and the total area of corneocytes stripped on the adhesive surface of the removed tape, instead of the adhesive area of the tape relative to the skin surface, were measured.

Results/Conclusions:

The dermal peeling force of the permeable tape gradually increased and that of the occlusive tape decreased. The increase in the former could be caused by the increase in the adhesive area of the tape relative to the skin surface, and the decrease in the latter could be caused by reduction of the bonding force among the corneocytes themselves, according to hydration.
Melanin distribution in corneocytes and fine patterns of pigmentation on pigmented areas in pigmentary disorders
Authors: Sakamaki Takeshi , Hayashi Shoji , Hayakawa Ritsuko
Published: February 2007

Background/aims:

Hyperpigmentation on the face, such as chloasma, ephelides, and senile pigmentation, is a common problem in the dermatological field. It is desirable to obtain precise data on melanin distribution and hyperpigmentation patterns for correct diagnosis and suitable treatment; however, there are few reports of non‐invasive studies of hyperpigmentation of the face skin.

Methods:

In this study, we examined melanin distribution in corneocytes and fine patterns of pigmentation. Using adhesive tape, we stripped the skin on both pigmented areas and adjacent normal areas of the face. The melanin granules in the cells of the stripped specimens were stained by the Fontana‐Masson stain method. The melanin distribution of corneocytes was categorized into five types, and the frequency of each type was calculated. Pigmentation patterns were imaged by a videomicroscope equipped with a polarizer. The fine patterns of pigmentation were categorized into three basic patterns: reticulated, granulated and flat pigmentation.

Results:

Melanin granules were concentrated around the nuclei in pigmented areas compared with normal areas. The frequency of each fine pattern was different in each pigmented disease.

Conclusions:

This study will be useful in assisting dermatologists in correcting clinical diagnoses of pigmented skin diseases.
Traffic Jams: Dynamic Models for Neurofilament Accumulation in Motor Neuron Disease
Authors: Shea Thomas B. , Beaty William J.
Published: February 2007

The dynamics of axonal transport are often colloquially described using highway traffic as a model system. Examination of the physics of traffic patterns, with emphasis on traffic jams and accidents, provides unique and perhaps counterintuitive insight into the aberrant accumulation of neurofilaments that accompanies amyotrophic lateral sclerosis/motor neuron disease.
Toward Polycontextually Sensitive Research Methods
Authors: Shapiro Debra L. , Glinow Mary Ann Von , Xiao Zhixing
Published: February 2007

In this paper we introduce the concept of ’polycontextuality,’ which refers to multiple and qualitatively different contexts embedded within one another. We distinguish polycontextuality from the singularly contextual types of description typically provided by social scientists, and use the case of China to elucidate polycontextual phenomena. Polycontextuality can include verbal- and non-verbal nuances whose understanding is rooted in local, cognitive, emotional and even spiritual references -most of which cannot be easily observed or historically studied. For this reason we recommend the polycontexual sensitive research method to supplement the scientific deductive research typically designed to study observable phenomena based on a singular context (e.g. verbal) that are controllable by the researcher's stimuli and/or measures. Actions for increasing scholars’ polycontextual sensitivity are suggested, and guidelines for the scholar interested in doing high quality indigenous research are offered, using the case of China for illustrative purposes.
Does the Colour of the Cat Matter? The Red Hat Strategy in China's Private Enterprises
Authors: Chen Wenhong
Published: February 2007

The proliferation of new property rights regimes in transitional economies provided an opportunity to examine the interaction between institutions and organizations. Some private enterprises in China developed the Red Hat strategy whereby they disguised their private ownership by registering as a public-owned organization. Drawing on a national survey, this study investigated how institutional variations, transaction costs and social embeddedness affected the firms’ Red Hat strategy. The findings suggest that private firms preferred a fuzzy property rights arrangement in the early years of market transition. The temporal and regional variation of the institutional environment contributed to the adoption of the Red Hat strategy. High transaction costs — networking cost and resource constraints — were positively related to the adoption of the Red Hat strategy. Social embeddedness also played an important role. The reliance on transaction partners in the public sector increased the pressure to adopt the Red Hat, while connections with high-ranking cadres facilitated the process. However, private firms opted for clearly delineated property rights as the institutional environment improved. In turn, the decisions of individual firms affected the institutional environment at the aggregate level. The Red Hat strategy exemplifies the co-evolution of institutional change and organizational dynamics.
Language Fluency, Socialization and Inter-Unit Relationships in Chinese and Finnish Subsidiaries
Authors: Barner-Rasmussen Wilhelm , Björkman Ingmar
Published: February 2007

High levels of trust and shared vision contribute to collaborative behaviour among units belonging to the same corporation. We examined the relationship of language fluency and socialization mechanisms to inter-unit shared vision and trustworthiness, using a sample of 310 inter-unit relationships involving subsidiaries of multinational corporations located in China and Finland. Results show that language fluency related significantly to shared vision and perceived trustworthiness in both the Chinese and Finnish subsidiaries. We also found socialization mechanisms to have a positive relationship to shared vision in the Chinese but not the Finnish sample, and no significant relationship to perceived trustworthiness in either sample. The interaction effects of language fluency and socialization mechanisms produced different results in the Chinese and Finnish samples. The study confirmed the importance of language fluency for inter-unit relationships and offered several suggestions for future research.
Developmental State and Corporate Governance in China
Authors: Nee Victor , Opper Sonja , Wong Sonia
Published: February 2007

China's state-guided economic miracle has revitalized a long-standing and unsettled debate about the role of government in transformative economic development. In a firm-level study of corporate governance we examine whether direct state involvement actually makes a positive contribution to the economic performance of newly incorporated firms in China's urban economy. We show that direct intervention into the governance of firms is likely to yield negative economic effects at the firm level. We infer from our findings that it must be other types of government intervention external to the firm that explain the success of China's developmental state in promoting rapid economic growth.
Purification of phosphoproteins by immobilized metal affinity chromatography and its application to phosphoproteome analysis
Authors: Machida Mitsuyo , Kosako Hidetaka , Shirakabe Kyoko , Kobayashi Michimoto , Ushiyama Masato , Inagawa Junichi , Hirano Joe , Nakano Tomoyo , Bando Yasuhiko , Nishida Eisuke , Hattori Seisuke
Published: February 2007

Prefractionation procedures facilitate the identification of lower‐abundance proteins in proteome analysis. Here we have optimized the conditions for immobilized metal affinity chromatography (IMAC) to enrich for phosphoproteins. The metal ions, Ga(III), Fe(III), Zn(II), and Al(III), were compared for their abilities to trap phosphoproteins; Ga(III) was the best. Detailed analyses of the pH and ionic strength for IMAC enabled us to determine the optimal conditions (pH 5.5 and 0.5 m NaCl). When whole cell lysates were fractionated in this way, about one‐tenth of the total protein was recovered in the eluate, and the recovery of phosphorylated extracellular signal‐regulated kinase (ERK) was more than 90%. Phosphorylated forms of ribosomal S6 kinase (RSK) and Akt were also enriched efficiently under the same conditions. Our Ga(III) IMAC and a commercially available purification kit for phosphoproteins performed similarly, with a slight difference in the spectrum of phosphoproteins. When phosphoproteins enriched from NIH3T3 cells in which ERK was either activated or suppressed were analyzed by two‐dimensional fluorescence difference gel electrophoresis, phosphorylated ERK was detected as discrete spots unique to ERK‐activated cells, which overlapped with surrounding spots in the absence of prefractionation. We applied the same technique to search for Akt substrates and identified Abelson interactor 1 as a novel potential target. These results demonstrate the efficacy of phosphoprotein enrichment by IMAC and suggest that this procedure will be of general use in phosphoproteome research.
Molecular cloning and sequencing of MHC class II beta 1 domain of turkey reveals high sequence identity with chicken
Authors: Ahmed K. A. , Saxena V. K. , Saxena M. , Ara A. , Pramod A. B. , Rajaram M. L. , Dorman K. S. , Majumdar S. , Rasool T. J.
Published: February 2007

We report the nucleotide sequences of turkey (Meleagris gallopavo) major histocompatibility complex (MHC) class II loci (β 1 domain or exon 2 encoding the peptide‐binding region). In the present investigation, three distinct sequences from the β 1 domain of turkey MHC class II were isolated. A BLAST search and phylogenetic analysis revealed that turkey MHC sequences are most similar to chicken and peacock MHC. There was no strong evidence of recombination among the turkey MHC sequences or with other avian MHC, but diversity was high. The diversity in this peptide‐binding region may be the result of point mutation and balancing selection or frequent gene conversion within turkey. However, more work and data are needed to understand the evolution of turkey and other avian MHC. Moreover, polymerase chain reaction–restriction fragment‐length polymorphism analysis of exon 2 using the Hinf I restriction enzyme demonstrated three restriction patterns and a preliminary evidence of multiple β loci in turkey. PCR‐RFLP analysis of turkey MHC class II loci could be a promising method of MHC genotyping, when more sequences are available. Turkey MHC haplotypes identified earlier by RFLP analysis should be sequenced to standardize turkey MHC nomenclature and to develop DNA based method of haplotyping.
Discovery of HLA‐DRB1*0331 in a Taiwanese marrow donor and the importance of sequence‐based typing in a rare or previously unrecognized allele
Authors: Yang K. L. , Chu C. C. , Huang C. H. , Lin S. Z. , Hsu W. L. , Liu D. W. , Lin P. Y.
Published: February 2007

We describe here a novel HLA‐DRB1* allele, DRB1*0331, observed from a Taiwanese bone marrow donor using DNA sequence‐based typing (SBT) method. The ‘new’ allele differs from DRB1*0306 and DRB1*0325 by one nucleotide at positions 196 and 227, respectively. Nucleotide mutations caused amino acid substitutions from N to Y at codon 37 and from F to Y at codon 47, as compared with amino acid sequence encoded by the DRB1*030101 allele. The donor was first typed as DRB1*0403/0406/0439/0441/0446/0451/0452 (NMDP code DRB1*04XX) and DRB1*0304/0323/0325 (NMDP code DRB1*03APDA) by sequence‐specific oligonucleotide (SSO) typing kit. Subsequent typing of the donor by high‐resolution sequence‐specific primer (SSP) protocol indicated DRB1*0403 and DRB1*0306. The anomalous result of DRB1*03 was resolved by SBT and recognized as DRB1*0331. We concluded that SSP or SSO alone may mistype a precedent unrecognized allele and that two different typing techniques or SBT may have to be employed to safe guard true HLA typing when rare alleles are encountered at the first time.
Cytokine gene polymorphisms in the Dutch population
Authors: Skorpil N. , Kolesár L. , Striz I. , Lardy N. M. , Slavcev A.
Published: February 2007

Numerous studies have shown that variations in the production and activity of cytokines influence the susceptibility and/or resistance to various infectious agents, autoimmune diseases, and cancer, as well as the predisposition to allograft rejection. Differences in the production of cytokines between individuals are often caused by single nucleotide polymorphisms (SNP) in the promoter or coding regions of cytokine genes.

The cytokine polymorphisms of 107 unrelated Caucasian individuals originating from various parts of the Netherlands were studied and compared with the results of two European (Czech and Italian) populations. Twenty‐two SNPs of 13 different cytokine genes were analysed. To test the Hardy–Weinberg equilibrium, allele frequencies were estimated by direct gene counting. Evaluation of the allele frequencies of the Dutch, Italian and Czech populations showed that five SNPs were significantly different between the Dutch and the Italians, while these SNPs did not vary between the Dutch and the Czechs. This analysis, in combination with other types of immune profiling, may be helpful for prediction of the clinical outcome of various infectious and immune‐related disorders, as well as for estimation of the risk for rejection and graft vs. host disease after organ or stem cell transplantation.
Adjuvant radiotherapy to an initial bulky mass in diffuse large B‐cell lymphoma: lack of survival benefit
Authors: TOMITA N. , KODAMA F. , MOTOMURA S. , ITOH S. , OHSHIMA R. , HYO R. , KAWANO T. , HASHIMOTO C. , TAKEMURA S. , YAMAZAKI E. , FUJITA H. , FUJISAWA S. , OGAWA K. , KANAMORI H. , ISHIGATSUBO Y.
Published: February 2007

The role of adjuvant radiotherapy to the site of the initial bulky mass in lymphoma remains to be determined. We retrospectively analyzed clinical data for 35 consecutive patients with diffuse large B‐cell lymphoma who had an initial bulky mass were treated successfully by chemotherapy reaching complete remission or complete remission unconfirmed according to International Workshop Criteria. Median age was 57 years. Median follow‐up period for surviving patients after completion of chemotherapy was 45 months. Twenty patients (group A) received adjuvant radiotherapy to the bulky mass, while 15 (group B) did not. Median dose of radiation in group A was 40 Gy (range, 30–60 Gy). In group A, four relapses occurred, all from other sites; group B included three relapses from bulky and one from other sites. Overall survival (P = 0.15) and recurrence‐free survival (P = 0.48) did not differ significantly between groups. Although adjuvant radiotherapy to the initial bulky site is useful for controlling local disease, no survival benefit was seen.
Evidence for a Locus in 1p31 Region Specifically Linked to the Co-Morbidity of Asthma and Allergic Rhinitis in the EGEA Study
Authors: Dizier Marie-Hélène , Bouzigon Emmanuelle , Guilloud-Bataille Michel , Genin Emmanuelle , Oryszczyn Marie-Pierre , Annesi-Maesano Isabella , Demenais Florence
Published: February 2007

Objective: A recent genome scan conducted in French EGEA families led to detect linkage of 1p31 to either asthma or allergic rhinitis (AR) and more significantly to asthma associated with AR. The goal of the present study was to assess formally whether 1p31 is a linkage region shared by two different diseases, asthma and AR, or whether it is specific to the co-morbidity asthma plus AR. Methods: We used two different statistical approaches: the Triangle Test Statistic (TTS) and the Predivided Sample Test (PST), to search for heterogeneity of linkage to 1p31 according to the affection status being defined by either the presence of the two diseases (asthma plus AR) or the presence of only one disease (‘asthma only’ or ‘AR only’ or ‘asthma only or AR only’). Results: While no heterogeneity between the ‘two diseases’ phenotype and the ‘one disease’ phenotype was detected by the TTS, there was significant evidence for heterogeneity (p = 0.00007/0.002 after correction for multiple testing) using the PST. There was no indication of linkage in sib-pairs with ‘one disease’ only, while there was significant evidence for linkage in sib-pairs displaying asthma plus AR (p = 0.0002/0.0016 after correction). Conclusion: The present analysis shows that the co-morbidity, asthma plus AR, represents a phenotypic entity, distinct from asthma only or AR only, controlled by a genetic factor located on 1p31.
Use and Misuse of the Receiver Operating Characteristic Curve in Risk Prediction
Authors: Cook Nancy R.
Published: February 2007

The
c
statistic, or area under the receiver operating characteristic (ROC) curve, achieved popularity in diagnostic testing, in which the test characteristics of sensitivity and specificity are relevant to discriminating diseased versus nondiseased patients. The
c
statistic, however, may not be optimal in assessing models that predict future risk or stratify individuals into risk categories. In this setting, calibration is as important to the accurate assessment of risk. For example, a biomarker with an odds ratio of 3 may have little effect on the
c
statistic, yet an increased level could shift estimated 10-year cardiovascular risk for an individual patient from 8% to 24%, which would lead to different treatment recommendations under current Adult Treatment Panel III guidelines. Accepted risk factors such as lipids, hypertension, and smoking have only marginal impact on the
c
statistic individually yet lead to more accurate reclassification of large proportions of patients into higher-risk or lower-risk categories. Perfectly calibrated models for complex disease can, in fact, only achieve values for the
c
statistic well below the theoretical maximum of 1. Use of the
c
statistic for model selection could thus naively eliminate established risk factors from cardiovascular risk prediction scores. As novel risk factors are discovered, sole reliance on the
c
statistic to evaluate their utility as risk predictors thus seems ill-advised.
Calcium/Vitamin D Supplementation and Cardiovascular Events
Authors: Hsia Judith , Heiss Gerardo , Ren Hong , Allison Matthew , Dolan Nancy C. , Greenland Philip , Heckbert Susan R. , Johnson Karen C. , Manson JoAnn E. , Sidney Stephen , Trevisan Maurizio
Published: February 2007

Background—

Individuals with vascular or valvular calcification are at increased risk for coronary events, but the relationship between calcium consumption and cardiovascular events is uncertain. We evaluated the risk of coronary and cerebrovascular events in the Women’s Health Initiative randomized trial of calcium plus vitamin D supplementation.

Methods and Results—

We randomized 36 282 postmenopausal women 50 to 79 years of age at 40 clinical sites to calcium carbonate 500 mg with vitamin D 200 IU twice daily or to placebo. Cardiovascular disease was a prespecified secondary efficacy outcome. During 7 years of follow-up, myocardial infarction or coronary heart disease death was confirmed for 499 women assigned to calcium/vitamin D and 475 women assigned to placebo (hazard ratio, 1.04; 95% confidence interval, 0.92 to 1.18). Stroke was confirmed among 362 women assigned to calcium/vitamin D and 377 assigned to placebo (hazard ratio, 0.95; 95% confidence interval, 0.82 to 1.10). In subgroup analyses, women with higher total calcium intake (diet plus supplements) at baseline were not at higher risk for coronary events (
P
=0.91 for interaction) or stroke (
P
=0.14 for interaction) if assigned to active calcium/vitamin D.

Conclusions—

Calcium/vitamin D supplementation neither increased nor decreased coronary or cerebrovascular risk in generally healthy postmenopausal women over a 7-year use period.
A Simple Multicloud Parameterization for Convectively Coupled Tropical Waves. Part II: Nonlinear Simulations
Authors: Khouider Boualem , Majda Andrew J.
Published: February 2007

Observations in the Tropics point to the important role of three cloud types, congestus, stratiform, and deep convective clouds, besides ubiquitous shallow boundary layer clouds for both the climatology and large-scale organized anomalies such as convectively coupled Kelvin waves, two-day waves, and the Madden–Julian oscillation. Recently, the authors have developed a systematic model convective parameterization highlighting the dynamic role of the three cloud types through two baroclinic modes of vertical structure: a deep convective heating mode and a second mode with lower troposphere heating and cooling corresponding respectively to congestus and stratiform clouds. The model includes both a systematic moisture equation where the lower troposphere moisture increases through detrainment of shallow cumulus clouds, evaporation of stratiform rain, and moisture convergence and decreases through deep convective precipitation and also a nonlinear switch that favors either deep or congestus convection depending on whether the lower middle troposphere is moist or dry. Here these model convective parameterizations are applied to a 40 000-km periodic equatorial ring without rotation, with a background sea surface temperature (SST) gradient and realistic radiative cooling mimicking a tropical warm pool. Both the emerging “Walker cell” climatology and the convectively coupled wave fluctuations are analyzed here while various parameters in the model are varied. The model exhibits weak congestus moisture coupled waves outside the warm pool in a turbulent bath that intermittently amplify in the warm pool generating convectively coupled moist gravity wave trains propagating at speeds ranging from 15 to 20 m s−1 over the warm pool, while retaining a classical Walker cell in the mean climatology. The envelope of the deep convective events in these convectively coupled wave trains often exhibits large-scale organization with a slower propagation speed of 3–5 m s−1 over the warm pool and adjacent region. Occasional much rarer intermittent deep convection also occurs outside the warm pool. The realistic parameter regimes in the multicloud model are identified as those with linearized growth rates for large scale instabilities roughly in the range of 0.5 K day−1.
Effects of Diurnal Variations on Tropical Equilibrium States: A Two-Dimensional Cloud-Resolving Modeling Study
Authors: Gao Shouting , Zhou Yushu , Li Xiaofan
Published: February 2007

Effects of diurnal variations on tropical heat and water vapor equilibrium states are investigated based on hourly data from two-dimensional cloud-resolving simulations. The model is integrated for 40 days and the simulations reach equilibrium states in all experiments. The simulation with a time-invariant solar zenith angle produces a colder and drier equilibrium state than does the simulation with a diurnally varied solar zenith angle. The simulation with a diurnally varied sea surface temperature generates a colder equilibrium state than does the simulation with a time-invariant sea surface temperature. Mass-weighted mean temperature and precipitable water budgets are analyzed to explain the thermodynamic differences. The simulation with the time-invariant solar zenith angle produces less solar heating, more condensation, and consumes more moisture than the simulation with the diurnally varied solar zenith angle. The simulation with the diurnally varied sea surface temperature produces a colder temperature through less latent heating and more IR cooling than the simulation with the time-invariant sea surface temperature.
Interacting Mountain Waves and Boundary Layers
Authors: Smith Ronald B.
Published: February 2007

Linear hydrostatic 3D mountain wave theory is extended to include a thin frictional boundary layer (BL), parameterized using two characteristic relaxation times for wind adjustment. The character of the BL is described using a “compliance coefficient,” defined as the ratio of BL thickness change to imposed pressure. In this formulation the simplest model that captures the two-way interaction between mountain waves and the boundary layer is sought. The slower BL wind speed amplifies the wind response and shifts it upstream so that the wind maxima occur in regions of favorable pressure gradient, not at points of minimum pressure. Variations in BL thickness reduce the mountain wave amplitude. The BL effect is sensitive to the wind profile convexity. The boundary layer improves the linear theory description of windy peaks. Low-level flow splitting is enhanced and wave breaking aloft is reduced. The BL also decreases the amount of upslope orographic precipitation. The wave momentum flux reduction by the BL is greater than the pressure drag reduction, indicating that part of the pressure drag is taken from BL momentum.
A General Method for Conserving Energy and Potential Enstrophy in Shallow-Water Models
Authors: Salmon Rick
Published: February 2007

The shallow-water equations may be posed in the form df /dt = {F, H, Z}, where H is the energy, Z is the potential enstrophy, and the Nambu bracket {F, H, Z} is completely antisymmetric in its three arguments. This makes it very easy to construct numerical models that conserve analogs of the energy and potential enstrophy; one need only discretize the Nambu bracket in such a way that the antisymmetry property is maintained. Using this strategy, this paper derives explicit finite-difference approximations to the shallow-water equations that conserve mass, circulation, energy, and potential enstrophy on a regular square grid and on an unstructured triangular mesh. The latter includes the regular hexagonal grid as a special case.
Potential Vorticity as Meridional Coordinate
Authors: Stan Cristiana , Randall David A.
Published: February 2007

The dynamical equations of atmospheric flow are written using potential vorticity as the meridional coordinate and potential temperature as the vertical coordinate. Within this system, the atmosphere is divided into undulating tubes bounded by isentropic and constant potential vorticity surfaces, and, under adiabatic and frictionless conditions, the air moves through the tubes without penetrating through the walls.
Spectral Properties of One-Dimensional Diffusive Systems Subject to Stochastic Forcing
Authors: Liu H-L.
Published: February 2007

The vertical wavenumber and frequency spectra of horizontal wind and temperature in stochastically driven systems with diffusion, either due to uniform background eddy and molecular transport, or due to adjustment processes associated with shear or convective instability, are studied. Because of the dominating role of vertical transport in a stratified fluid, one-dimensional Langevin-type equations could be ascribed to such systems in the vertical direction. The linear equation with uniform diffusion is solved explicitly, and the spectra follow power-law distributions if the stochastic force is Gaussian. The nonlinear equations with gradient (either shear or lapse rate) dependent diffusion coefficients are shown to support scale invariance, and the power-law indices of the spectra are determined from dynamic renormalization group (DRG) analysis under rather general conditions. The exact power-law indices vary with the spectrum of the stochastic force and the nonlinearity of the systems. If the wavenumber spectrum of the force is moderately red (between k0 and k−2), the spectral indices of horizontal wind and temperature and the range of their variability are in general agreement with those inferred from wind and temperature measurements. The indices in both linear and nonlinear cases are confirmed by numerical simulations. This theory may suggest an alternative explanation to the universal vertical wavenumber and frequency spectra and their variability. By relating the universal spectra to systems characterized by stochastic forcing and background diffusion or diffusive adjustment due to shear or convective instability, which are ubiquitous in a stratified fluid, the difficulty to associate the time- and location-independent spectral features directly with the highly time- and location-dependent gravity waves or wave-breaking events is avoided. If such systems are suggestive of the real atmosphere, there is a need to be cautious in making assumptions regarding gravity waves solely based on the universal spectra when analyzing and interpreting wind and temperature observations.
Cloud Activating Properties of Aerosol Observed during CELTIC
Authors: Stroud Craig A. , Nenes Athanasios , Jimenez Jose L. , DeCarlo Peter F. , Huffman J. Alex , Bruintjes Roelof , Nemitz Eiko , Delia Alice E. , Toohey Darin W. , Guenther Alex B. , Nandi Sreela
Published: February 2007

Measurements of aerosol size distribution, chemical composition, and cloud condensation nuclei (CCN) concentration were performed during the Chemical Emission, Loss, Transformation, and Interactions with Canopies (CELTIC) field program at Duke Forest in North Carolina. A kinetic model of the cloud activation of ambient aerosol in the chamber of the CCN instrument was used to perform an aerosol–CCN closure study. This study advances prior investigations by employing a novel fitting algorithm that was used to integrate scanning mobility particle sizer (SMPS) measurements of aerosol number size distribution and aerosol mass spectrometer (AMS) measurements of the mass size distribution for sulfate, nitrate, ammonium, and organics into a single, coherent description of the ambient aerosol in the size range critical to aerosol activation (around 100-nm diameter). Three lognormal aerosol size modes, each with a unique internally mixed composition, were used as input into the kinetic model. For the two smaller size modes, which control CCN number concentration, organic aerosol mass fractions for the defined cases were between 58% and 77%. This study is also unique in that the water vapor accommodation coefficient was estimated based on comparing the initial timing for CCN activation in the instrument chamber with the activation predicted by the kinetic model. The kinetic model overestimated measured CCN concentrations, especially under polluted conditions. Prior studies have attributed a positive model bias to an incomplete understanding of the aerosol composition, especially the role of organics in the activation process. This study shows that including measured organic mass fractions with an assumed organic aerosol speciation profile (pinic acid, fulvic acid, and levoglucosan) and an assumed organic aerosol solubility of 0.02 kg kg−1 still resulted in a significant model positive bias for polluted case study periods. The slope and y intercept for the CCN predicted versus CCN observed regression was found to be 1.9 and −180 cm−3, respectively. The overprediction generally does not exceed uncertainty limits but is indicative that a bias exists in the measurements or application of model. From this study, uncertainties in the particle number and mass size distributions as the cause for the model bias can be ruled out. The authors are also confident that the model is including the effects of growth kinetics on predicted activated number. However, one cannot rule out uncertainties associated with poorly characterized CCN measurement biases, uncertainties in assumed organic solubility, and uncertainties in aerosol mixing state. Sensitivity simulations suggest that assuming either an insoluble organic fraction or external aerosol mixing were both sufficient to reconcile the model bias.
Closures for Ensemble-Mean Linear Dynamics with Stochastic Basic Flows
Authors: Jin F-F. , Lin L.
Published: February 2007

This paper demonstrates the validity of a second-order closure for the ensemble-mean dynamics using the approach of direct numerical ensemble simulations of a linear barotropic model with stochastic basic flows. For various configurations of the stochastic basic flow and external forcing, the deterministic solutions under the second-order closure capture, with remarkable accuracy, the ensemble means and the associated eddy covariance fields of forced responses simulated by a 500-member numerical ensemble. Thus, the second-order closure is found to be adequate for describing the ensemble-mean linear dynamics with stochastic basic flows. Moreover, simple analytical solutions based on the second-order closure also demonstrate that the stochastic component of a superrotational basic flow not only damps the ensemble-mean Rossby waves, but also enhances their eastward propagation. Various examples of ensemble-mean solutions all show the important role played by the stochastic synoptic eddy component of the basic flow in determining the ensemble-mean responses to external forcing. This study supports the notion that linear frameworks of ensemble-mean dynamics under second-order closure are useful tools for describing and understanding the dynamics of the synoptic eddy and the low-frequency flow (SELF) feedback and extratropical atmospheric low-frequency variability.
Characteristics of the Atlantic Storm-Track Eddy Activity and Its Relation with the North Atlantic Oscillation
Authors: Rivière G. , Orlanski I.
Published: February 2007

This study focuses on feedbacks of the high-frequency eddy activity onto the quasi-stationary circulation, particularly with regard to the North Atlantic Oscillation (NAO). The methodology consists of analyzing NCEP–NCAR reanalysis data and sensitivity runs from a high-resolution nonhydrostatic regional model. Consistent with recent studies, results show that the jet displacement characteristic of the NAO phenomenon depends strongly on the dynamics of the synoptic-scale waves and the way they break. Positive and negative phases of the NAO are closely related to anticyclonic and cyclonic wave breaking, respectively. Indeed, the high-frequency momentum flux whose sign is directly related to the type of wave breaking is correlated with the NAO index over the Atlantic. The peak of the momentum flux signal precedes that of the NAO by a few days suggesting that wave breaking is triggering NAO events. Two examples illustrate the significant impact of single storms, in particular those occurring in the east coast of the United States. The wave breaking at the end of their life cycle can suddenly change the NAO index in few days, and as the return to equilibrium takes generally a longer time, it can even affect the sign of the NAO during an entire month.

An important issue determining the NAO phase is related to upstream effects. By considering a domain extending from the eastern Pacific to western Europe and by forcing the regional model with real data at the western boundary, sensitivity runs show that the right sign of the NAO index can be recovered. It indicates that waves coming from the eastern Pacific are crucial for determining the NAO phase. According to their spatial scales and frequencies when they reach the Atlantic domain, they can break one way or another and push the Atlantic jet equatorward or poleward. Synoptic waves with periods between 5 and 12 days break anticyclonically whereas those with periods between 2 and 5 days break both anticyclonically and cyclonically with a predominance for cyclonic wave breaking. Another crucial factor concerns surface effects. Cyclonic wave breaking in the upper levels is strongly connected with an explosive cyclonic development at the surface accompanied by strong surface moisture fluxes whereas such an explosive growth is not present in the anticyclonic wave breaking case. Finally, it is proposed that these results are not only useful for explaining the intraseasonal variations of the NAO but would serve also as a basis for understanding its interannual and interdecadal variations.