bluuebunny/crossref_metadata_2025 huggingface dataset:
Development of the Vascular Supply in Rat Skeletal Muscles
Authors: Bogusch G.
Published: July 2008

The vascular development in the extensor muscles of rat forelegs from 12-day-old embryos up to 9-day-old animals was investigated with a light microscope using semithin plastic sections. On late day 12, blood vessels are distributed over the whole cross sectional area of the foreleg. On early day 13, a rearrangement of the blood vessels is visible. Now an avascular centre is enclosed by a vascularized tissue mantle, in which the muscle anlage starts developing. Few capillaries are visible within the muscle anlage. After differentiation of the muscle anlage into individual muscles the epimysium is passed by a netlike capillary plexus enwrapping the first avascular muscles. With the establishment of the perimysium on day 16 of embryonic development some capillaries are also visible within the individual muscles. The diameter of the capillaries is by far larger than the diameter of the myotubes. In older embryos the perimysium shows an increasing number of such large capillaries, whereas in the epimysium the capillaries are less frequent. In the perimysium a few additional capillaries with a small diameter of about 5 µm occur. On day 3 postpartum, small capillaries are also visible within the muscle fibre bundles. In the perimysium many large capillaries are still obvious. The vascular supply on day 9 postpartum, resembles that in adult muscles. The vascular supply of the muscles progresses from their periphery to more and more smaller compartments within the muscles, in close correlation to the establishment of the muscular connective tissue.
High-Density Lipoprotein Reduces the Human Monocyte Inflammatory Response
Authors: Murphy Andrew J. , Woollard Kevin J. , Hoang Anh , Mukhamedova Nigora , Stirzaker Roslynn A. , McCormick Sally P.A. , Remaley Alan T. , Sviridov Dmitri , Chin-Dusting Jaye
Published: July 2008

Objective—

Whereas the anti–inflammatory effects of high-density lipoprotein (HDL) on endothelial cells are well described, such effects on monocytes are less studied.

Methods and Results—

Human monocytes were isolated from whole blood followed by assessment of CD11b activation/expression and cell adhesion under shear-flow. HDL caused a dose-dependent reduction in the activation of CD11b induced by PMA or receptor-dependent agonists. The constituent of HDL responsible for the antiinflammatory effects on CD11b activation was found to be apolipoprotein A-I (apoA-I). Cyclodextrin, but not cyclodextrin/cholesterol complex, also inhibited PMA-induced CD11b activation implicating cholesterol efflux as the main mechanism. This was further confirmed with the demonstration that cholesterol content of lipid rafts diminished after treatment with the cholesterol acceptors. Blocking ABCA1 with an anti-ABCA1 antibody abolished the effect of apoA-I. Furthermore, monocytes derived from a Tangier disease patient definitively confirmed the requirement of ABCA1 in apoA-I–mediated CD11b inhibition. The antiinflammatory effects of apoA-I were also observed in functional models including cell adhesion to an endothelial cell monolayer, monocytic spreading under shear flow, and transmigration.

Conclusions—

HDL and apoA-I exhibit an antiinflammatory effect on human monocytes by inhibiting activation of CD11b. ApoA-I acts through ABCA1, whereas HDL may act through several receptors.
Mechanisms of the Factor V Leiden Paradox
Authors: van Stralen K.J. , Doggen C.J.M. , Bezemer I.D. , Pomp E.R. , Lisman T. , Rosendaal F.R.
Published: July 2008

Objective—

Carriers of the factor V Leiden mutation (FVL-carriers) have a substantially increased risk of deep venous thrombosis (DVT), whereas the risk of pulmonary embolism (PE) is only mildly increased compared with noncarriers. So far few studies have investigated possible mechanisms for this so-called FVL paradox.

Methods and Results—

Consecutive patients with a first DVT or PE were included in a large population-based case-control study (MEGA study). Patients, aged 18 to 70 years, provided a questionnaire, DNA (n=3313), or plasma (n=1474). Surgery, injury, and travel were considered thrombosis-provocative. Of 2063 patients with isolated DVT, 20% were FVL-carrier, as were 8% of the 885 patients with isolated PE. Among DVT patients, FVL-carriers had their thrombi more often proximal and a higher number of affected veins than noncarriers. No differences were observed between FVL-carriers and noncarriers in time between provocation and diagnosis, in vitro coagulation time, and thrombus density. Compared with patients with both DVT and PE, isolated DVT patients more often had thrombi located distally and had a similar number of affected veins. Compared with isolated PE patients, isolated DVT patients had a similar time between provocation and diagnosis, and similar in vitro coagulation time and thrombus density.

Conclusion—

Although some effects were differential for FVL-carriers and noncarriers, and some were differential for PE and DVT patients, none of the potential mechanisms offered a clear explanation.
Longitudinal Change in Serum Gamma-Glutamyltransferase and Cardiovascular Disease Mortality
Authors: Strasak Alexander M. , Kelleher Cecily C. , Klenk Jochen , Brant Larry J. , Ruttmann Elfriede , Rapp Kilian , Concin Hans , Diem Günter , Pfeiffer Karl P. , Ulmer Hanno ,   the VHM&PP Study Group
Published: July 2008

Objective—

The purpose of this study was to investigate the association of longitudinal change in serum γ-glutamyltransferase (GGT) with mortality from cardiovascular disease (CVD).

Methods and Results—

A population-based cohort of 76 113 Austrian men and women with 455 331 serial GGT measurements was prospectively followed-up for a median of 10.2 years after assessment of longitudinal GGT change during an average period of 6.9 years. Cox proportional hazards regression with time-varying covariates was used to evaluate GGT change as an independent predictor for CVD death. Independently of baseline GGT and other classical CVD risk factors, a pronounced increase in GGT (7-year change >9.2 U/L) was significantly associated with increased total CVD mortality in men (
P
=0.005); the adjusted hazard ratio (95% confidence interval) in comparison to stable GGT (7-year change −0.7 to 1.3 U/L) was 1.40 (1.09 to 1.81). Similarly, total CVD risk was elevated for increasing GGT in women, although effects were less pronounced and statistically significant only in subanalyses regarding coronary heart disease. Age of participants significantly modified the relation between GGT change and CVD mortality, with markedly stronger associations to be observable for younger individuals.

Conclusion—

Our study is the first to demonstrate that a longitudinal increase in GGT, independently of baseline GGT and even within its normal range, significantly increases risk of fatal CVD.
VEGF Stimulates HDAC7 Phosphorylation and Cytoplasmic Accumulation Modulating Matrix Metalloproteinase Expression and Angiogenesis
Authors: Ha Chang Hoon , Jhun Bong Sook , Kao Hung-Ying , Jin Zheng-Gen
Published: July 2008

Objective—

Histone acetylation/deacetylation plays an important role in the control of gene expression, tissue growth, and development. In particular, histone deacetylases 7 (HDAC7), a member of class IIa HDACs, is crucial in maintaining vascular integrity. However, whether HDAC7 is involved in the processes of vascular endothelial signaling and angiogenesis remains unclear. Here, we investigated the role of HDAC7 in vascular endothelial growth factor (VEGF) signaling and angiogenesis.

Methods and Results—

We show for the first time that VEGF stimulated phosphorylation of HDAC7 at the sites of Ser178, Ser344, and Ser479 in a dose- and time-dependent manner, which leads to the cytoplasmic accumulation of HDAC7. Using pharmacological inhibitors, siRNA, and adenoviruses carrying dominant-negative mutants, we found that phospholipase Cγ/protein kinase C/protein kinase D1 (PKD1)-dependent signal pathway mediated HDAC7 phosphorylation and cytoplasmic accumulation by VEGF. Infection of ECs with adenoviruses encoding a mutant of HDAC7 specifically deficient in PKD1-dependent phosphorylation inhibited VEGF-induced angiogenic gene expression, including matrix metalloproteinases MT1-matrix metalloproteinase (MMP) and MMP10. Moreover, HDAC7 and its targeting genes were involved in VEGF-stimulated endothelial cell migration, tube formation, and microvessel sprouting.

Conclusions—

Our results demonstrate that VEGF stimulates PKD1-dependent HDAC7 phosphorylation and cytoplasmic accumulation in endothelial cells modulating gene expression and angiogenesis.
Hypoxia-Induced Apelin Expression Regulates Endothelial Cell Proliferation and Regenerative Angiogenesis
Authors: Eyries Mélanie , Siegfried Géraldine , Ciumas Mariana , Montagne Kevin , Agrapart Monique , Lebrin Franck , Soubrier Florent
Published: July 2008

Apelin has been identified as the endogenous ligand of the human orphan G protein–coupled receptor APJ. This peptide exerts a variety of cardiovascular effects and particularly acts as an activator of angiogenesis. Importantly, hypoxia has been reported to regulate apelin expression but the molecular mechanism underlying hypoxia-induced apelin expression and the relationship with the physiological response of the apelin/APJ system are still not established. Here, we demonstrate that apelin expression is induced by hypoxia in cultured endothelial and vascular smooth muscle cells as well as in lung from mice exposed to acute hypoxia. Transient transfection experiments show that hypoxia-inducible transcriptional activation of apelin requires an intact hypoxia-responsive element (+813/+826) located within the first intron of the human apelin gene. Chromatin immunoprecipitation assay reveals that hypoxia-inducible factor-1α binds to the endogenous hypoxia-responsive element site of the apelin gene. Moreover, overexpression of hypoxia-inducible factor-1α increases the transcriptional activity of a reporter construct containing this hypoxia-responsive element, whereas small interfering RNA–mediated hypoxia-inducible factor-1α knockdown abolishes hypoxia-induced apelin expression. Finally, microinterfering RNA-mediated apelin or APJ receptor knockdown inhibits both hypoxia-induced endothelial cell proliferation in vitro and hypoxia-induced vessel regeneration in the caudal fin regeneration of Fli-1 transgenic zebrafish. The hypoxia-induced apelin expression may, thus, provide a new mechanism involved in adaptive physiological and pathophysiological response of vascular cells to low oxygen level.
Practical Model-Based Dose Finding in Early-Phase Clinical Trials
Authors: Whelan Harry T. , Cook John D. , Amlie-Lefond Catherine M. , Hovinga Collin A. , Chan Anthony K. , Ichord Rebecca N. , deVeber Gabrielle A. , Thall Peter F.
Published: July 2008

Background and Purpose—

A safe and effective tissue plasminogen activator (tPA) dose for childhood stroke has not been established. This article describes a Bayesian outcome-adaptive method for determining the best dose of an experimental agent and explains how this method was used to design a dose-finding trial for tPA in childhood.

Methods—

The method assigns doses to successive cohorts of patients on the basis of each dose’s desirability, quantified in terms of the tradeoff between efficacy and toxicity. The tradeoff function is constructed from several pairs of equally desirable (efficacy, toxicity) probabilities specified by the physicians planning the trial. Each cohort’s dose is chosen adaptively, based on dose-outcome data from the patients treated previously in the trial, to optimize the efficacy-toxicity tradeoff. Application of the method to design the tPA trial is described, including a computer simulation study to establish design properties. A hypothetical cohort-by-cohort example is given to illustrate how the method works during trial conduct.

Results and Conclusions—

Because only a dose that is both safe and efficacious may be selected and the method combines phase I and phase II by integrating efficacy and toxicity to choose doses, it avoids the more time-consuming and expensive conventional approach of conducting a phase I trial based on toxicity alone followed by a phase II trial based on efficacy alone. This is especially useful in settings with low accrual rates, such as trials of tPA for pediatric acute ischemic stroke.
Carotid Intima Media Thickness and Plaques Can Predict the Occurrence of Ischemic Cerebrovascular Events
Authors: Prati Patrizio , Tosetto Alberto , Vanuzzo Diego , Bader Giovanni , Casaroli Marco , Canciani Luigi , Castellani Sergio , Touboul Pierre-Jean
Published: July 2008

Background and Purpose—

The clinical usefulness of noninvasive measurement of carotid intima media thickness and plaque visualization in the general population is still uncertain.

Methods—

We evaluated the age-specific incidence rates of cerebrovascular events in a cohort of 1348 subjects randomly taken from the census list of San Daniele Township and followed for a mean period of 12.7 years. The association among common carotid intima media thickness, measured at baseline, arterial risk factors, and incidence of ischemic cerebrovascular events was modeled using Poisson regression. The predictive ability of common carotid intima media thickness over arterial risk factors (summarized in the Framingham Stroke Risk Score) was evaluated by receiver operating characteristic curve analysis.

Results—

During the follow-up, 115 subjects developed nonfatal ischemic stroke, transient ischemic attack, or vascular death, which were the predefined study end points. After adjustment for age and sex, hypertension, diabetes, common carotid intima media thickness above 1 mm, and carotid plaques were all independent risk factors for development of vascular events. Inclusion of carotid findings (presence of common carotid intima media thickness above 1 mm or carotid plaques) resulted in a predictive power higher than Framingham Stroke Risk Score alone only on for those subjects with a Framingham Stroke Risk Score over 20%.

Conclusions—

Although common carotid intima media thickness and presence of carotid plaques are known to be risk factors for the development of vascular events and to be independent from the conventional risk factors summarized in the Framingham Stroke Risk Score, their contribution to individual risk prediction is limited. Further studies will be required to address the role of carotid ultrasonography in the primary prevention of high-risk subjects.
Contralesional Axonal Remodeling of the Corticospinal System in Adult Rats After Stroke and Bone Marrow Stromal Cell Treatment
Authors: Liu Zhongwu , Li Yi , Zhang Xueguo , Savant-Bhonsale Smita , Chopp Michael
Published: July 2008

Background and Purpose—

Motor recovery after stroke is associated with neuronal reorganization in bilateral hemispheres. We investigated contralesional corticospinal tract remodeling in the brain and spinal cord in rats after stroke and treatment of bone marrow stromal cells.

Methods—

Adult male Wistar rats were subjected to permanent right middle cerebral artery occlusion. Phosphate-buffered saline or bone marrow stromal cells were injected into a tail vein 1 day postischemia. An adhesive removal test was performed weekly to monitor functional recovery. Threshold currents of intracortical microstimulation on the left motor cortex for evoking bilateral forelimb movements were measured 6 weeks after stroke. When intracortical microstimulation was completed, biotinylated dextran amine was injected into the left motor cortex to anterogradely label the corticospinal tract. At 4 days before euthanization, pseudorabies virus-152-EGFP and 614-mRFP were injected into left or right forelimb extensor muscles, respectively. All animals were euthanized 8 weeks after stroke.

Results—

In normal rats (n=5), the corticospinal tract showed a unilateral innervation pattern. In middle cerebral artery occlusion rats (n=8), our data demonstrated that: 1) stroke reduced the stimulation threshold evoking ipsilateral forelimb movement; 2) EGFP-positive pyramidal neurons were increased in the left intact cortex, which were labeled from the left stroke-impaired forelimb; and 3) biotinylated dextran amine-labeled contralesional axons sprouted into the denervated spinal cord. Bone marrow stromal cells significantly enhanced all 3 responses (n=8,
P
<0.05).

Conclusions—

Our data demonstrated that corticospinal tract fibers originating from the contralesional motor cortex sprout into the denervated spinal cord after stroke and bone marrow stromal cells treatment, which may contribute to functional recovery.
Immediate Clinical Outcome of Patients Harboring Unruptured Intracranial Aneurysms Treated by Endovascular Approach
Authors: Pierot Laurent , Spelle Laurent , Vitry Fabien
Published: July 2008

Background and Purpose—

The management of unruptured intracranial aneurysms remains controversial and the results of endovascular treatment are not precisely known because no prospective data exist. The first prospective multicenter study (ATENA) was conducted in Canada and France to determine clinical outcome and risks of this treatment.

Methods—

Six hundred forty-nine patients harboring a total of 1100 aneurysms from 27 Canadian and French neurointerventional centers were prospectively and consecutively treated by endovascular coil embolization. Of these, 739 unruptured intracranial aneurysms were treated during 700 procedures. Aneurysms were selectively treated in the great majority of cases (98.4%) with coils alone (54.5%), the balloon remodeling technique (37.3%), or stenting (7.8%).

Results—

Endovascular treatment failed in 32 aneurysms (4.3%). Technical adverse events with or without clinical modification were encountered in 15.4% of patients and included thromboembolic complications (7.1% per procedure), intraoperative rupture (2.6% per procedure), and device-related problems (2.9% per procedure). Adverse events associated with transient or permanent neurological deficit or death were encountered in 5.4% of cases. The 1-month morbidity and mortality rates were 1.7% and 1.4%, respectively.

Conclusions—

Endovascular treatment of unruptured intracranial aneurysms is feasible in a high percentage of cases with low morbidity and mortality rates.
Recurrent Events in Transient Ischemic Attack and Minor Stroke
Authors: Coutts Shelagh B. , Hill Michael D. , Campos Cynthia R. , Choi Young B. , Subramaniam Suresh , Kosior Jayme C. , Demchuk Andrew M.
Published: July 2008

Background and Purpose—

The risk of a recurrent stroke after transient ischemic attack (TIA) or minor stroke is high. Clinical trials are needed to assess acute treatment options in these patients. We sought to evaluate the type of recurrent events and to identify which subsets of patients are at risk for recurrent events.

Methods—

One hundred and eighty patients with TIA or minor stroke were examined within 12 hours and underwent brain MRI within 24 hours. Any neurological deterioration was recorded, and a combination of clinical and MRI factors were used to create a combined event classification. Subgroups of patients analyzed included classical TIA, patients with NIHSS=0, and patients with NIHSS >0 in ED.

Results—

Overall there were 38 events in 36 patients (20% event rate); 20 were symptomatic and 18 were silent (only evident because of the follow up MRI). 18/20 (90%) symptomatic events were associated with progression of presenting symptoms, compared to 2/20 (10%) with a clear recurrent stroke distinct from the original event. We found a low risk of recurrent stroke among classical definition TIA patients (1.1%). Patients with an NIHSS=0 in the ED, had an intermediate event rate (6.6%) between TIA (classical – 1.1%) and NIHSS >0 (14.4%; χ
2
test for trend,
P
=0.02). All clinical categories of patient (TIA, stroke, NIHSS=0) accumulated silent lesions on MRI.

Conclusions—

Most events were classified as stroke progression or infarct growth rather than a recurrent stroke. A low risk of recurrence was found in patients with classical TIA and those with no neurological deficits on initial assessment.
Deletion of Angiotensin II Type 2 Receptor Attenuates Protective Effects of Bone Marrow Stromal Cell Treatment on Ischemia–Reperfusion Brain Injury in Mice
Authors: Iwanami Jun , Mogi Masaki , Li Jian-Mei , Tsukuda Kana , Min Li-Juan , Sakata Akiko , Fujita Teppei , Iwai Masaru , Horiuchi Masatsugu
Published: July 2008

Background and Purpose—Protective effects of bone marrow stromal cells (MSCs) on ischemic brain damage have been highlighted. We examined the possibility that deletion of AT2receptor could attenuate the cerebroprotective effects of MSC using AT2receptor-deficient mice (Agtr2−) and the effect of selective AT1receptor blocker.

Methods—Wild-type mice (Agtr2+) were subjected to 3 hours of focal brain ischemia followed by reperfusion (ischemia–reperfusion injury). Simultaneously,Agtr2+-MSC,Agtr2−-MSC, or saline was injected through the tail vein.

Results—Survival rates at 6 days after ischemia–reperfusion injury were as follows: approximately 50% in saline-injected mice, 80% inAgtr2+-MSC-injected mice, and 20% inAgtr2−-MSC-injected mice. Neurological deficit after ischemia–reperfusion injury was improved inAgtr2+-MSC-injected mice, but not inAgtr2−-MSC-injected mice. After 48 hours of ischemia–reperfusion injury, brain infarct size was reduced inAgtr2+-MSC-injected mice, but not inAgtr2−-MSC-injected mice. Moreover, brain edema was significantly ameliorated inAgtr2+-MSC-treated mice but not inAgtr2−-MSC-treated mice. Furthermore, the increase in mRNA expression of tumor necrosis factor-α and monocyte chemoattractant protein-1 in the ischemic brain was less inAgtr2+-MSC-treated mice in the ipsilateral site, but was similar in the contralateral hemisphere. Tumor necrosis factor-α level was increased in both the contralateral hemisphere and ipsilateral hemisphere ofAgtr2−-MSC-treated mice. In contrast, monocyte chemoattractant protein-1 levels tended to increaseAgtr2−-MSC-treated mice without a significant difference. Treatment of MSC with an AT1receptor blocker, valsartan, significantly improved survival rates inAgtr2−-MSC-injected mice.

Conclusions—These results suggest that AT2receptor signaling in MSC attenuated brain damage and neurological deficit (deleted).
The Association Between Kidney Disease and Cardiovascular Risk in a Multiethnic Cohort
Authors: Nickolas Thomas L. , Khatri Minesh , Boden-Albala Bernadette , Kiryluk Krzysztof , Luo Xiaodong , Gervasi-Franklin Palma , Paik Myunghee , Sacco Ralph L.
Published: July 2008

Background and Purpose—

The objective of this study was to determine the relationship between chronic kidney disease (CKD), race–ethnicity, and vascular outcomes.

Methods—

A prospective, multiracial cohort of 3298 stroke-free subjects with 6.5 years of mean follow-up time for vascular outcomes (stroke, myocardial infarction, vascular death) was used. Kidney function was estimated using serum creatinine and Cockcroft-Gault formula. Cox proportional hazards models were fitted to evaluate the relationship between kidney function and vascular outcomes.

Results—

In multivariate analysis, Cockcroft-Gault formula between 15 and 59 mL/min was associated with a significant 43% increased stroke risk in the overall cohort. Blacks with Cockcroft-Gault formula between 15 and 59 mL/min had significantly increased risk of both stroke (hazard ratio, 2.65; 95% CI, 1.47 to 4.77) and combined vascular outcomes (hazard ratio, 1.59; 95% CI, 1.10–2.92).

Conclusion—

Chronic kidney disease is a significant risk factor for stroke and combined vascular events, especially in blacks.
Longitudinal Analysis of Quality of Life for Stroke Survivors Using Latent Curve Models
Authors: Pan Jun Hao , Song Xin Yuan , Lee Sik Yum , Kwok Timothy
Published: July 2008

Background and Purpose—For the survivors, activities of daily living, handicap, and depression have a significant impact on health-related quality of life (HRQOL). How the dynamic changes of these variables relate to HRQOL over time in the subacute phase of stroke recovery has not been investigated. The objective of this study was to study longitudinal behaviors of HRQOL of the stroke survivors in relation to the changes in activities of daily living, handicap, and depression after stroke.

Methods—This was a prospective cohort study of first disabling patients with stroke. Subjects were interviewed at 3, 6, and 12 months after stroke for modified Barthel Index, London Handicap Scale, Geriatric Depression Scale, and the World Health Organization Quality of Life questionnaire (abbreviated Hong Kong version). A latent curve model was developed to analyze how the dynamic changes in activities of daily living, handicap, and depressive mood related to the changes in HRQOL.

Results—Two hundred forty-seven of 303 patients (82%) followed up at 3 months after stroke could complete the quality-of-life questionnaire. Their mean age was 68.8 years. The latent curve model analysis revealed that initial physical health HRQOL was independently associated with activities of daily living, handicap, and depression. The other 3 HRQOL domain scores were primarily associated with depression only. The rates of change in all 4 domains of HRQOL were significantly and inversely associated with rate of change in the Geriatric Depression Scale only.

Conclusion—Change in mood in the postacute phase of stroke recovery is the most significant determinant of change in HRQOL. More attention should be paid to the detection and management of poststroke depression.
Prevalence and Correlates of Subclinical Atherosclerosis in Alaska Eskimos
Authors: Cutchins Alexis , Roman Mary J. , Devereux Richard B. , Ebbesson Sven O.E. , Umans Jason G. , Zhu Jianhui , Weissman Neil J. , Howard Barbara V.
Published: July 2008

Background and Purpose—

The recent increase in clinical cardiovascular disease in Alaska Eskimos suggests that changes in traditional lifestyle may have adverse public health consequences. This study examines the prevalence of subclinical vascular disease and its relation to risk factors in Alaska Eskimos.

Methods—

Participants in the population-based Genetics of Coronary Artery Disease in Alaska Natives (GOCADAN) Study underwent evaluation of cardiovascular disease risk factors and carotid ultrasound. Outcome variables were carotid intimal-medial thickness and presence and extent of atherosclerosis.

Results—

In multivariate analyses, intimal-medial thickness and presence and extent of atherosclerosis were all associated with traditional cardiovascular disease risk factors but not dietary intake of omega-3 fatty acids. Rates of carotid atherosclerosis were higher than those reported in 2 large population-based US studies.

Conclusions—

Alaska Eskimos have similar traditional risk factors for carotid atherosclerosis as other ethnic and racial populations but have higher prevalences of atherosclerosis, possibly attributable to higher rates of smoking.
National Board Certification for Teachers: What Does It Cost and How Does It Compare?
Authors: Rice Jennifer King , Hall L. Jane
Published: July 2008

National Board Certification (NBC) for teachers has become an important innovation in long-standing efforts to improve teacher quality. As states, districts, and teachers increasingly invest resources in this process, information is needed on its cost, impact, and value. This analysis estimates the full opportunity cost of four NBC support programs, examines how the cost burden is distributed, and compares the cost of NBC with the cost of the traditionally dominant approach for teachers' skill development and salary advancement: earning a master's degree. The study demonstrates that the application fee accounts for only 7--13 percent of the total cost of NBC. Costs are shouldered by a range of individuals and organizations, with the greatest burden on NBC candidates themselves. Our comparison with the cost of earning a master's degree suggests that NBC is the less costly approach, with implications for choosing among alternative resource investments to promote, recognize, and reward effective teachers.
Using Available Evidence to Estimate the Cost of Educational Adequacy
Authors: Odden Allan R. , Goetz Michael E. , Picus Lawrence O.
Published: July 2008

This article seeks to move the adequacy issue forward by demonstrating that under a certain set of assumptions, it is possible to provide a set of programmatic offerings that corresponds well with what we consider to be an emerging, research-based consensus about what constitutes best practices. We do this by showing what could be purchased with the national average expenditure per pupil if it were to be applied to one adequacy approach, the evidence-based approach, and how these resources have been linked to increases in student performance.
Sensitivity Study of Cloud-Resolving Convective Simulations with WRF Using Two Bulk Microphysical Parameterizations: Ice-Phase Microphysics versus Sedimentation Effects
Authors: Hong Song-You , Sunny Lim Kyo-Sun , Kim Ju-Hye , Jade Lim Jeong-Ock , Dudhia Jimy
Published: July 2008

This study examines the relative importance of ice-phase microphysics and sedimentation velocity for hydrometeors in bulk microphysics schemes. The two bulk microphysics schemes having the same number of prognostic water substances, the Weather Research and Forecasting (WRF) Single-Moment 6-Class Microphysics Scheme (WSM6) and the Purdue–Lin scheme (PLIN), are evaluated for a 2D idealized storm case and for a 3D heavy rainfall event over Korea. The relative importance of microphysics and sedimentation velocity for ice particles is illuminated by the additional experiments that exchange the sedimentation velocity formula for graupel in the two schemes. In a 2D idealized storm simulation test bed, it is found that, relative to the PLIN scheme, the WSM6 scheme develops the storm late with weakened intensity because of a slower sedimentation velocity for graupel. Such a weakened intensity of precipitation also appears in a 3D model framework when the WSM6 scheme is used, in conjunction with the overall distribution of the precipitation band southward toward what was observed. The major reason is found to be the ice-phase microphysics of the WSM6 and related ice-cloud–radiation feedback, rather than the smaller terminal velocity for graupel in the WSM6 than in the PLIN scheme.
Shepard and Hardy Multiquadric Interpolation Methods for Multicomponent Aerosol–Cloud Parameterization
Authors: Rap Alexandru , Ghosh Satyajit , Smith Michael H.
Published: July 2008

This paper presents a novel method based on the application of interpolation techniques to the multicomponent aerosol–cloud parameterization for global climate modeling. Quantifying the aerosol indirect effect still remains a difficult task, and thus developing parameterizations for general circulation models (GCMs) of the microphysics of clouds and their interactions with aerosols is a major challenge for climate modelers. Three aerosol species are considered in this paper—namely sulfate, sea salt, and biomass smoke—and a detailed microphysical chemical parcel model is used to obtain a dataset of points relating the cloud droplet number concentration (CDNC) to the three aerosol input masses. The resulting variation of CDNC with the aerosol mass has some nonlinear features that require a complex but efficient parameterization to be easily incorporated into GCMs. In bicomponent systems, simple interpolation techniques may be sufficient to relate the CDNC to the aerosol mass, but with increasing components, simple methods fail. The parameterization technique proposed in this study employs either the modified Shepard interpolation method or the Hardy multiquadrics interpolation method, and the numerical results obtained show that both methods provide realistic results for a wide range of aerosol mass loadings. This is the first application of these two interpolation techniques to aerosol–cloud interaction studies.
Analysis of Convective Transport and Parameter Sensitivity in a Single Column Version of the Goddard Earth Observation System, Version 5, General Circulation Model
Authors: Ott L. E. , Bacmeister J. , Pawson S. , Pickering K. , Stenchikov G. , Suarez M. , Huntrieser H. , Loewenstein M. , Lopez J. , Xueref-Remy I.
Published: July 2008

Convection strongly influences the distribution of atmospheric trace gases. General circulation models (GCMs) use convective mass fluxes calculated by parameterizations to transport gases, but the results are difficult to compare with trace gas observations because of differences in scale. The high resolution of cloud-resolving models (CRMs) facilitates direct comparison with aircraft observations. Averaged over a sufficient area, CRM results yield a validated product directly comparable to output from a single global model grid column. This study presents comparisons of vertical profiles of convective mass flux and trace gas mixing ratios derived from CRM and single column model (SCM) simulations of storms observed during three field campaigns. In all three cases, SCM simulations underpredicted convective mass flux relative to CRM simulations. As a result, the SCM simulations produced lower trace gas mixing ratios in the upper troposphere in two of the three storms than did the CRM simulations.

The impact of parameter sensitivity in the moist physics schemes employed in the SCM has also been examined. Statistical techniques identified the most significant parameters influencing convective transport. Convective mass fluxes are shown to be strongly dependent on chosen parameter values. Results show that altered parameter settings can substantially improve the comparison between SCM and CRM convective mass flux. Upper tropospheric trace gas mixing ratios were also improved in two storms. In the remaining storm, the SCM representation of CO2 was not improved because of differences in entrainment and detrainment levels in the CRM and SCM simulations.
Climate Regime Variability for Past and Present Time Slices Simulated by the Fast Ocean Atmosphere Model
Authors: Handorf Dörthe , Dethloff Klaus , Marshall Andrew G. , Lynch Amanda
Published: July 2008

This paper presents an analysis of Northern Hemisphere climate regime variability for three different time slices, simulated by the Fast Ocean Atmosphere Model (FOAM). The three time slices are composed of present-day conditions, the mid-Holocene, and the Last Glacial Maximum (LGM). Climate regimes have been determined by analyzing the structure of a spherical probability density function in a low-dimensional state space spanned by the three leading empirical orthogonal functions. This study confirms the ability of the FOAM medium-resolution climate model to reproduce low-frequency climate variability in the form of regime-like behavior. Three to four regimes have been detected for each time slice. Compared with present-day conditions, new climate regimes appeared for the LGM. For the mid-Holocene, which had slightly different boundary conditions and external forcings than the present-day simulation, the frequency of occurrence of the regimes was altered while only slight changes were found in the structure of some regimes.
Predictors of Tropical Cyclone Numbers and Extreme Hurricane Intensities over the North Atlantic Using Generalized Additive and Linear Models
Authors: Mestre Olivier , Hallegatte Stéphane
Published: July 2008

Fluctuations of the annual number of tropical cyclones over the North Atlantic and of the energy dissipated by the most intense hurricane of a season are related to a variety of predictors [global temperature, SST and detrended SST, North Atlantic Oscillation (NAO), Southern Oscillation index (SOI)] using generalized additive and linear models. This study demonstrates that SST and SOI are predictors of interest. The SST is found to influence positively the annual number of tropical cyclones and the intensity of the most intense hurricanes. The use of specific additive models reveals nonlinearity in the responses to SOI that has to be taken into account using changepoint models. The long-term trend in SST is found to influence the annual number of tropical cyclones but does not add information for the prediction of the most intense hurricane intensity.
Warming of the Upper Equatorial Indian Ocean and Changes in the Heat Budget (1960–99)
Authors: Alory Gaël , Meyers Gary
Published: July 2008

In the equatorial Indian Ocean, sea surface has warmed by 0.5°–1°C over the 1960–99 period, while waters have cooled at thermocline depth and the net atmospheric heat flux has decreased. Among a set of twentieth-century climate simulations from 12 coupled models, the Centre National de Recherches Météorologiques Coupled Global Climate Model version 3 (CNRM-CM3) reproduces key observed features of these changes. It is used to investigate changes in the heat budget of the upper equatorial Indian Ocean and identify mechanisms responsible for the warming. By comparing twentieth-century and control simulations, significant shifts in the mean balance of the heat budget between the preindustrial and the 1960–99 periods can be identified. The main cause of the surface warming is a decrease in the upwelling-related oceanic cooling. It occurs in the thermocline dome region because of a slowdown of the wind-driven Ekman pumping. The observed decrease in net heat flux is a negative feedback driven by evaporation, which is enhanced by the equatorial warming and associated strengthening of trade winds.
Improving the Numerical Solution of Soil Moisture–Based Richards Equation for Land Models with a Deep or Shallow Water Table
Authors: Zeng Xubin , Decker Mark
Published: July 2008

The soil moisture–based Richards equation is widely used in land models for weather and climate studies, but its numerical solution using the mass-conservative scheme in the Community Land Model is found to be deficient when the water table is within the model domain. Furthermore, these deficiencies cannot be reduced by using a smaller grid spacing. The numerical errors are much smaller when the water table is below the model domain. These deficiencies were overlooked in the past, most likely because of the more dominant influence of the free drainage bottom boundary condition used by many land models. They are fixed here by explicitly subtracting the hydrostatic equilibrium soil moisture distribution from the Richards equation. This equilibrium distribution can be derived at each time step from a constant hydraulic (i.e., capillary plus gravitational) potential above the water table, representing a steady-state solution of the Richards equation. Furthermore, because the free drainage condition has serious deficiencies, a new bottom boundary condition based on the equilibrium soil moisture distribution at each time step is proposed that also provides an effective and direct coupling between groundwater and surface water.
On the Interaction of Time-Variable Flows with a Shelfbreak Canyon
Authors: Kämpf Jochen
Published: July 2008

Process-oriented hydrodynamic modeling is employed to study the interaction of along-slope flows with an idealized submarine shelfbreak canyon. The model is forced via prescription of oscillatory flows superposed on steady background flows of various strength and direction. Findings suggest that purely oscillatory flow does not produce significant net onshore transport of dense water. It is rather the steady component of the flow that creates substantial up-canyon flows of ∼0.05 Sv (1 Sv = 106 m3 s−1) in volume transport. This takes place exclusively for flows running on average against the propagation direction of coastal Kelvin waves, whereas flows of the opposite direction operate to suppress cross-shelf density fluxes.
Atmospheric Control on the Thermohaline Circulation
Authors: Czaja Arnaud
Published: July 2008

In an attempt to elucidate the role of atmospheric and oceanic processes in setting a vigorous ocean overturning circulation in the North Atlantic but not in the North Pacific, a comparison of the observed atmospheric circulation and net surface freshwater fluxes over the North Atlantic and Pacific basins is conducted. It is proposed that the more erratic meridional displacements of the atmospheric jet stream over the North Atlantic sector is instrumental in maintaining high surface salinities in its subpolar gyre. In addition, it is suggested that the spatial pattern of the net freshwater flux at the sea surface favors higher subpolar Atlantic salinity, because the geographical line separating net precipitation from net evaporation is found well south of the time-mean gyre separation in the North Pacific, whereas the two lines tend to coincide in the North Atlantic. Numerical experiments with an idealized two-gyre system confirm that these differences impact the salinity budget of the subpolar gyre.

Further analysis of a coupled climate model in which the Atlantic meridional overturning cell has been artificially weakened suggests that the more erratic jet fluctuations in the Atlantic and the shift of the zero [net evaporation minus precipitation (E − P)] line are likely explained by features independent of the state of the thermohaline circulation. It is thus proposed that the atmospheric circulation helps “locking” high surface salinities and an active coupling between upper and deep ocean layers in the North Atlantic rather than in the North Pacific basin.
Orthogonal Channel Coding for Simultaneous Co- and Cross-Polarization Measurements
Authors: Chandrasekar V. , Bharadwaj Nitin
Published: July 2008

Dual-polarization weather radars typically measure the radar reflectivity at more than one polarization state for transmission and reception. Historically, dual-polarization radars have been operated at copolar and cross-polar states defined with respect to the transmit polarization states. Recently, based on the improved understanding of the propagation properties of electromagnetic waves in precipitation media, the simultaneous transmit and receive (STAR) mode has become common to simplify the hardware. In the STAR mode of operation, horizontal and vertical polarization states are transmitted simultaneously and samples of both horizontal and vertical copolar returns are obtained. A drawback of the current implementation of STAR mode is its inability to measure parameters obtained from cross-polar signals such as linear depolarization ratio (LDR). In this paper, a technique to obtain cross-polar signals with STAR mode waveform is presented. In this technique, the horizontally and vertically polarized transmit waveforms are coded with orthogonal phase sequences. The performance of the phase-coded waveform is determined by the properties of the phase codes. This orthogonal phase coding technique is implemented in the Colorado State University–University of Chicago–Illinois State Water Survey (CSU–CHILL) radar. This paper outlines the methodology and presents the performance of the cross-polar and copolar parameter estimation based on the simulation as well as data collected from the CSU–CHILL radar.
Nature of the Mesoscale Boundary Layer Height and Water Vapor Variability Observed 14 June 2002 during the IHOP_2002 Campaign
Authors: Couvreux F. , Guichard F. , Austin P. H. , Chen F.
Published: July 2008

Mesoscale water vapor heterogeneities in the boundary layer are studied within the context of the International H2O Project (IHOP_2002). A significant portion of the water vapor variability in the IHOP_2002 occurs at the mesoscale, with the spatial pattern and the magnitude of the variability changing from day to day. On 14 June 2002, an atypical mesoscale gradient is observed, which is the reverse of the climatological gradient over this area. The factors causing this water vapor variability are investigated using complementary platforms (e.g., aircraft, satellite, and in situ) and models. The impact of surface flux heterogeneities and atmospheric variability are evaluated separately using a 1D boundary layer model, which uses surface fluxes from the High-Resolution Land Data Assimilation System (HRLDAS) and early-morning atmospheric temperature and moisture profiles from a mesoscale model. This methodology, based on the use of robust modeling components, allows the authors to tackle the question of the nature of the observed mesoscale variability. The impact of horizontal advection is inferred from a careful analysis of available observations. By isolating the individual contributions to mesoscale water vapor variability, it is shown that the observed moisture variability cannot be explained by a single process, but rather involves a combination of different factors: the boundary layer height, which is strongly controlled by the surface buoyancy flux, the surface latent heat flux, the early-morning heterogeneity of the atmosphere, horizontal advection, and the radiative impact of clouds.
A Simplified Dynamical System for Tropical Cyclone Intensity Prediction
Authors: DeMaria Mark
Published: July 2008

A simplified dynamical system for tropical cyclone intensity prediction based on a logistic growth equation (LGE) is developed. The time tendency of the maximum sustained surface winds is proportional to the sum of two terms: a growth term and a term that limits the maximum wind to an upper bound. The maximum wind evolution over land is determined by an empirical inland wind decay formula. The LGE contains four free parameters, which are the time-dependent growth rate and maximum potential intensity (MPI), and two constants that determine how quickly the intensity relaxes toward the MPI. The MPI is estimated from an empirical formula as a function of sea surface temperature and storm translational speed. The adjoint of the LGE provides a method for finding the other three free parameters to make the predictions as close as possible to the National Hurricane Center best-track intensities. The growth rate is assumed to be a linear function of the vertical shear (S), a convective instability parameter (C) determined from an entraining plume, and their product, where both S and C use global model fields as input. This assumption reduces the parameter estimation problem to the selection of six constants. Results show that the LGE optimized for the full life cycle of individual storms can very accurately simulate the intensity variations out to as long as 15 days. For intensity prediction, single values of the six constants are found by fitting the model to more than 2400 Atlantic forecasts from 2001 to 2006. Results show that the observed intensity variations can be fit more accurately with the LGE than with the linear Statistical Hurricane Intensity Prediction Scheme (SHIPS) formulation, and with a much smaller number of constants. Results also show that LGE model solution (and some properties of real storms) can be explained by the evolution in the two-dimensional S–C phase space. Forecast and other applications of the LGE model are discussed.