bluuebunny/crossref_metadata_2025 huggingface dataset:
Light at Night Activates IGF-1R/PDK1 Signaling and Accelerates Tumor Growth in Human Breast Cancer Xenografts
Authors: Wu Jinghai , Dauchy Robert T. , Tirrell Paul C. , Wu Steven S. , Lynch Darin T. , Jitawatanarat Potjana , Burrington Christine M. , Dauchy Erin M. , Blask David E. , Greene Michael W.
Published: February 2011

Regulation of diurnal and circadian rhythms and cell proliferation are coupled in all mammals, including humans. However, the molecular mechanisms by which diurnal and circadian rhythms regulate cell proliferation are relatively poorly understood. In this study, we report that tumor growth in nude rats bearing human steroid receptor-negative MCF-7 breast tumors can be significantly accelerated by exposing the rats to light at night (LAN). Under normal conditions of an alternating light/dark cycle, proliferating cell nuclear antigen (PCNA) levels in tumors were maximal in the early light phase but remained at very low levels throughout the daily 24-hour cycle period monitored. Surprisingly, PCNA was expressed in tumors continually at a high level throughout the entire 24-hour period in LAN-exposed nude rats. Daily fluctuations of Akt and mitogen activated protein kinase activation in tumors were also disrupted by LAN. These fluctuations did not track with PCNA changes, but we found that activation of the Akt stimulatory kinase phosphoinositide-dependent protein kinase 1 (PDK1) directly correlated with PCNA levels. Expression of insulin-like growth factor 1 receptor (IGF-1R), an upstream signaling molecule for PDK1, also correlated with fluctuations of PDK1/PCNA in the LAN group. In addition, circulating IGF-1 concentrations were elevated in LAN-exposed tumor-bearing nude rats. Finally, RNAi-mediated knockdown of PDK1 led to a reduction in PCNA expression and cell proliferation in vitro and tumor growth in vivo, indicating that PDK1 regulates breast cancer growth in a manner correlated with PCNA expression. Taken together, our findings demonstrate that LAN exposure can accelerate tumor growth in vivo, in part through continuous activation of IGF-1R/PDK1 signaling. Cancer Res; 71(7); 2622–31. ©2011 AACR.
Transfused Macrophages Ameliorate Pancreatic and Renal Injury in Murine Diabetes Mellitus
Authors: Zheng Dong , Wang Yiping , Cao Qi , Lee Vincent W.S. , Zheng Guoping , Sun Yan , Tan Thian K. , Wang Ya , Alexander Stephen I. , Harris David C.H.
Published: February 2011

Background: Alternatively activated macrophages (M2 macrophages) are able to reduce renal injury in murine adriamycin nephropathy. However, the effect of M2 macrophages in other renal diseases such as diabetic nephropathy remains unknown. Methods: Macrophages were separated from splenocytes and polarized with IL-4 and IL-13 into a protective phenotype. Mice underwent adoptive transfer with M2 macrophages, and then diabetes was induced by tail vein injection with streptozotocin (STZ). Blood glucose levels were monitored daily. Mice were sacrificed at week 10 after STZ. Renal function and histopathological injury were assessed quantitatively. Results: Transfused M2 macrophages accumulated progressively in kidneys for up to 10 weeks after STZ. Kidneys from diabetic mice transfused with M2 macrophages had less tubular atrophy, glomerular hypertrophy and interstitial expansion than did control diabetic mice. M2 macrophages suppressed the development of interstitial fibrosis. In addition, the degree of pancreatic islet injury, as assessed by insulin staining, haemoglobin A1c and blood glucose was reduced after transfusion of M2 macrophages. In vivo, activation of kidney endogenous macrophage cytokine expression was inhibited by M2 macrophages. Conclusion: Our findings show that M2 macrophages can protect against islet and renal injury in streptozotocin-induced diabetes, providing a potential therapeutic strategy for diabetes and diabetic nephropathy.
Inhibitory Effects of Oenothera biennis (Evening Primrose) Seed Extract on Streptococcus mutans and S. mutans-Induced Dental Caries in Rats
Authors: Matsumoto-Nakano M. , Nagayama K. , Kitagori H. , Fujita K. , Inagaki S. , Takashima Y. , Tamesada M. , Kawabata S. , Ooshima T.
Published: February 2011

Background: Oenothera biennis (evening primrose) seed extract (OBSE) is known to contain polyphenols, which may possess antioxidant activities. Polyphenols extracted from several plants are reported to exhibit cariostatic activities by inhibiting mutans streptococcus growth and glucosyltransferase activities. The purpose of the present study was to examine the inhibitory effects of OBSE on the development of dental caries, both in vitro and in vivo. Methods: OBSE was investigated for its inhibitory effects on cellular aggregation, hydrophobicity, sucrose-dependent adherence and insoluble glucan synthesis. Furthermore, biofilm formation was examined in the presence of OBSE, using confocal microscopic imaging. An animal experiment was also performed to examine the in vivo effects. Results: OBSE induced a strong aggregation of Streptococcus mutans MT8148 cells, while cell surface hydrophobicity was decreased by approximately 90% at a concentration of 0.25 mg/ml. The sucrose-dependent adherence of the MT8148 cells was also reduced by addition of OBSE, with a reduction rate of 73% seen at a concentration of 1.00 mg/ml. Additionally, confocal microscopic observations revealed the biofilm development phase to be remarkably changed in the presence of OBSE. Furthermore, insoluble glucan synthesis was significantly reduced when OBSE was present at concentrations greater than 0.03 mg/ml. In an animal experiment, the caries scores in rats given OBSE (0.05 mg/ml in drinking water) were significantly lower than those in rats given water without OBSE. Conclusion: Our results indicate that OBSE has inhibitory activity on dental caries.
Neurogenesis, Cellular Plasticity and Cognition: The Impact of Stem Cells in the Adult and Aging Brain – A Mini-Review
Authors: Couillard-Despres Sebastien , Iglseder Bernhard , Aigner Ludwig
Published: February 2011

The hippocampus is a structure equipped with a high degree of flexibility and adaptation. In contrast to most structures of the adult central nervous system, the hippocampus can rely on a form of plasticity known as neurogenesis. The continuous provision of new neurons derived from resident adult neural stem cells appears to facilitate the execution of hippocampal-dependent tasks since reduction or blockage of neurogenesis is associated with cognitive impairments. Importantly, however, although hippocampal neurogenesis is maintained all throughout life, its levels decrease steadily along with aging. Notwithstanding some evidence that in age-matched animals neurogenesis levels and learning performance are tightly associated, these two parameters do not appear to be directly coupled when comparing individuals of various age groups. Additional components, and in particular experience, appear to play a fundamental roles in hippocampal functions. In this review, we speculate on the impact of neurogenesis level modulation on cognitive performances, putting in perspective recent studies made in the aging human population and in rodent models of aging.
Serum Selenium Levels in Hemodialysis Patients Are Significantly Lower than Those in Healthy Controls
Authors: Fujishima Yosuke , Ohsawa Masaki , Itai Kazuyoshi , Kato Karen , Tanno Kozo , Turin Tanvir Chowdhury , Onoda Toshiyuki , Endo Shigeatsu , Okayama Akira , Fujioka Tomoaki
Published: February 2011

Serum selenium levels have been thought to be decreased in hemodialysis patients; however, results of previous studies have been inconsistent. Population-based hemodialysis patients (n = 1,041) and randomly recruited healthy controls (n = 384) were enrolled. Serum selenium levels were determined by inductively coupled plasma mass spectrometry and compared in hemodialysis patients and controls using analysis of covariance after adjustment for confounding factors with p < 0.1 as the result of the multiple regression analysis. Age, serum albumin levels, hsCRP levels, LDLC levels, HDLC levels, regular drinking habit and hemodialysis treatment were significantly associated with serum selenium levels in multiple regression analysis. Multivariate-adjusted means (95% CIs) of serum selenium levels were 103 µg/l (101–105) in hemodialysis patients and 117 µg/l (114–121) in controls. Selenium levels in hemodialysis patients were decreased. Whether decreased serum selenium levels contribute to increased risks for morbidity and mortality in hemodialysis patients should be examined.
Surface Quality of Porcine Corneal Lenticules after Femtosecond Lenticule Extraction
Authors: Heichel Jens , Blum Marcus , Duncker Gernot I.W. , Sietmann Rabea , Kunert Kathleen S.
Published: February 2011

Purpose: To determine the surface characteristics of porcine corneal lenticules after Femtosecond Lenticule Extraction. Methods: The Carl Zeiss Meditec AG VisuMax® femtosecond laser system was used to create refractive corneal lenticules on 10 freshly isolated porcine eyes. The surface regularity on the corneal lenticules recovered was evaluated by assessing scanning electron microscopy images using an established scoring system. Results: All specimens yielded comparable score results of 5–7 points (SD = 0.59) per lenticule (score range minimum 4 to maximum 11 points). Surface irregularities were caused by tissue bridges, cavitation bubbles or scratches. Conclusion: The Femtosecond Lenticule Extraction procedure is capable of creating corneal lenticules of predictable surface quality. However, future studies should focus on the optimization of laser parameters as well as surgical technique to improve the regularity of the corneal stromal bed.
Effects of Mycophenolate Mofetil Combined with Corticosteroids for Induction Therapy of Microscopic Polyangiitis
Authors: Han Fei , Liu Guangyi , Zhang Xiaohui , Li Xiayu , He Qiang , He Xuelin , Li Qun , Wang Suya , Wang Huiping , Chen Jianghua
Published: February 2011

Aims: We prospectively compared the effects of oral mycophenolate mofetil (MMF) or intravenous cyclophosphamide (IVC) combined with corticosteroids for induction therapy of microscopic polyangiitis (MPA) with renal involvement over a follow-up period of 6 months. Methods: 41 MPA patients were randomly assigned to either the open-label MMF group or the IVC group. Patients in the MMF group (n = 19) received oral MMF 1.0 g/day (1.5 g/day for patients with a body weight >70 kg) and patients in the IVC group (n = 22) received IVC in monthly pulses of 1.0 g per pulse (0.8 g per pulse for patients with a body weight <50 kg). Both groups received intravenous methylprednisolone 360–500 mg/day for 3 days, followed by oral prednisone 0.6–0.8 mg/kg/day and gradual tapering. Results: There was no significant difference of estimated glomerular filtration rate (eGFR) level between the IVC and MMF groups at baseline. At 6 months, the eGFR level increased significantly in both groups, but there was no significant difference between the two. Three patients in the IVC group and 1 in the MMF group received maintenance dialysis within 6 months (p = 0.36). The remission rate was 63.6% in the IVC group and 78.9% in the MMF group (p = 0.23). Conclusion: MMF is effective for inducing remission in Chinese MPA patients and may represent an alternative therapy to monthly impulses of IVC.
Pivotal Role of Protein Kinase C
δ
in Angiotensin II–Induced Endothelial Cyclooxygenase-2 Expression
Authors: Wong Siu Ling , Lau Chi Wai , Wong Wing Tak , Xu Aimin , Au Chak Leung , Ng Chi Fai , Ng Simon Siu Man , Gollasch Maik , Yao Xiaoqiang , Huang Yu
Published: February 2011

Objective—

The purpose of this study was to examine the hypothesis that angiotensin II (Ang II) induced endothelial cyclooxygenase-2 (COX-2) expression, which in turn mediated the generation of proinflammatory cytokines.

Methods and Results—

Western blot analysis on primary rat endothelial cells showed Ang II induced COX-2 expression, which was abolished by cotreatment of p38 mitogen-activated protein kinase (SB 202190) and extracellular signal–regulated kinase 1/2 (PD 98059) inhibitors. Protein kinase C
δ
(PKC
δ
) inhibitor (rottlerin) prevented extracellular signal–regulated kinase 1/2 phosphorylation and COX-2 expression. The pivotal role of PKC
δ
was further supported by a similar stimulatory effect of the PKC activator on COX-2 expression, signified by Ang II–stimulated translocation of PKC
δ
to the plasma membrane, and confirmed by PKC
δ
phosphorylation at Tyr311. Small interfering RNA targeting PKC
δ
diminished COX-2 expression, which was further abrogated by SB 202190. Human mesenteric arteries incubated with Ang II showed increased levels of endothelial COX-2 and monocyte chemoattractant protein-1; the former was inhibited by SB 202190 plus rottlerin, whereas the latter was prevented by COX-2 inhibitor.

Conclusion—

The present study pinpoints a novel role of PKC
δ
in Ang II–induced endothelial COX-2 upregulation and identifies a COX-2-dependent proatherosclerotic cytokine monocyte chemoattractant protein-1. The findings raise the possibility of curtailing endothelial COX-2 expression as a means of limiting or preventing vascular inflammation.
Insulin Resistance and the Relationship of a Dyslipidemia to Coronary Heart Disease
Authors: Robins Sander J. , Lyass Asya , Zachariah Justin P. , Massaro Joseph M. , Vasan Ramachandran S.
Published: February 2011

Objective—

The goal of this study was to examine the effect of insulin resistance (IR) in subjects without diabetes on the relationship of a dyslipidemia with high triglycerides and low high-density lipoprotein cholesterol (HDL-C) to the development of coronary heart disease (CHD).

Methods and Results—

Lower and higher fasting plasma HDL-C and triglyceride concentrations (defined at the study population median) and presence or absence of IR (defined by upper quartile Homeostatic Model Assessment values) were related to the development of myocardial infarction or CHD death in Framingham Heart Study participants without diabetes or a history of CHD (n=2910) attending the 1991 to 1995 examination. During follow-up (mean, 14 years), 128 participants experienced an incident CHD event. With Kaplan-Meier plots, the incidence of CHD was significantly greater with than without IR at either the lowest HDL-C or the highest triglycerides (
P
<0.001). In multivariable Cox models adjusted for major CHD risk factors, including waist circumference, only subgroups with IR had a significantly higher incidence of CHD. Compared with a reference group without IR and with higher-than-median HDL-C or lower-than-median triglycerides, the hazard ratio (HR) for incident events was significant with only IR and a lower HDL-C (HR 2.83,
P
<0.001) or higher triglycerides (HR 2.50,
P
<0.001). These findings were similar in men and women.

Conclusion—

In this community-based sample exclusive of diabetes, incident CHD risk associated with plasma HDL-C or triglycerides was significantly increased only in the presence of IR.
Evidence That Chromium Modulates Cellular Cholesterol Homeostasis and ABCA1 Functionality Impaired by Hyperinsulinemia—Brief Report
Authors: Sealls Whitney , Penque Brent A. , Elmendorf Jeffrey S.
Published: February 2011

Objective—

Trivalent chromium (Cr
3+
) is an essential micronutrient. Findings since the 1950s suggest that Cr
3+
might benefit cholesterol homeostasis. Here we present mechanistic evidence in support of this role of Cr
3+
.

Methods and Results—

High-density lipoprotein cholesterol generation in 3T3-L1 adipocytes, which are rendered ineffective by the hyperinsulinemia that is known to accompany disorders of lipid metabolism, was corrected by Cr
3+
. Mechanistically, Cr
3+
reversed hyperinsulinemia-induced cellular cholesterol accrual and associated defects in cholesterol transporter ATP-binding cassette transporter-A1 trafficking and apolipoprotein A1–mediated cholesterol efflux. Moreover, direct activation of AMP-activated protein kinase, which is known to be activated by Cr
3+
, or inhibition of hexosamine biosynthesis pathway activity, which is known to be elevated by hyperinsulinemia, mimics Cr
3+
action.

Conclusion—

These findings suggest a mechanism of Cr
3+
action that fits with long-standing claims of its role in cholesterol homeostasis. Furthermore, these data imply a mechanistic basis for the coexistence of dyslipidemia with hyperinsulinemia.
Timeliness of Tissue-Type Plasminogen Activator Therapy in Acute Ischemic Stroke
Authors: Fonarow Gregg C. , Smith Eric E. , Saver Jeffrey L. , Reeves Mathew J. , Bhatt Deepak L. , Grau-Sepulveda Maria V. , Olson DaiWai M. , Hernandez Adrian F. , Peterson Eric D. , Schwamm Lee H.
Published: February 2011

Background—

The benefits of intravenous tissue-type plasminogen activator (tPA) in acute ischemic stroke are time dependent, and guidelines recommend an arrival to treatment initiation (door-to-needle) time of ≤60 minutes.

Methods and Results—

Data from acute ischemic stroke patients treated with tPA within 3 hours of symptom onset in 1082 hospitals participating in the Get With the Guidelines–Stroke Program from April 1, 2003, to September 30, 2009 were studied to determine frequency, patient and hospital characteristics, and temporal trends in patients treated with door-to-needle times ≤60 minutes. Among 25 504 ischemic stroke patients treated with tPA, door-to-needle time was ≤60 minutes in only 6790 (26.6%). Patient factors most strongly associated with door-to-needle time ≤60 minutes were younger age, male gender, white race, or no prior stroke. Hospital factors associated with ≤60 minute door-to-needle time included greater annual volumes of tPA-treated stroke patients. The proportion of patients with door-to-needle times ≤60 minutes varied widely by hospital (0% to 79.2%) and increased from 19.5% in 2003 to 29.1% in 2009 (
P
<0.0001). Despite similar stroke severity, in-hospital mortality was lower (adjusted odds ratio, 0.78; 95% confidence interval, 0.69 to 0.90;
P
<0.0003) and symptomatic intracranial hemorrhage was less frequent (4.7% versus 5.6%;
P
<0.0017) for patients with door-to-needle times ≤60 minutes compared with patients with door-to-needle times >60 minutes.

Conclusions—

Fewer than one-third of patients treated with intravenous tPA had door-to-needle times ≤60 minutes, with only modest improvement over the past 6.5 years. These findings support the need for a targeted initiative to improve the timeliness of reperfusion in acute ischemic stroke.
Sex Differences in the Response to Poly(ADP-ribose) Polymerase-1 Deletion and Caspase Inhibition After Stroke
Authors: Liu Fudong , Lang Jesse , Li Jun , Benashski Sharon E. , Siegel Matthew , Xu Yan , McCullough Louise D.
Published: February 2011

Background and Purpose—

Emerging data suggest that the molecular cell death pathways triggered by ischemic insults differ in the male and female brain. Cell death in males is initiated by poly(ADP-ribose) polymerase-1 (PARP-1) activation; however, manipulation of this pathway paradoxically increases ischemic damage in females. In contrast, females are exquisitely sensitive to caspase-mediated cell death. The effect of caspase inhibition in PARP-1 knockout mice was evaluated to determine if the detrimental effects of PARP deletion in females were secondary to increased caspase activation.

Methods—

-Focal stroke was induced by transient or permanent middle cerebral artery occlusion (MCAO) in wild-type (WT) and PARP-1
−/−
mice of both sexes. The pan-caspase inhibitor, quinoline-Val-Asp(Ome)-CH2-O-phenoxy (Q-VD-OPh), was administered 90 minutes after middle cerebral artery occlusion. Infarct size and neurological sores were assessed. Separate cohorts were used for protein analysis for PAR, Apoptosis inducing factor (AIF), caspase-9, and caspase-3.

Results—

WT mice of both sexes had increased nuclear AIF after stroke compared to PARP-1
−/−
mice. PARP-1
−/−
females had higher mitochondrial cytochrome C and activated caspase-9 and -3 levels than WT female mice. PARP-1
−/−
females also had an increase in stroke-induced cytosolic cytochrome C release compared with WT females, which was not seen in males. Q-VD-OPh decreased caspase-9 in both males and females but only led to reduction of infarct in females. PARP-1
−/−
males had smaller infarcts, whereas PARP-1
−/−
females had larger strokes compared with WT. Q-VD-OPh significantly decreased infarct in both WT and PARP-1
−/−
females in both transient and permanent MCAO models, but had no effect in males.

Conclusions—

Deletion of PARP-1 reduces infarct in males but exacerbates injury in females. PARP-1
−/−
females have enhanced caspase activation. The detrimental effects of PARP loss in females can be reversed with caspase inhibition.
Cerebral Infarction After Subarachnoid Hemorrhage Contributes to Poor Outcome by Vasospasm-Dependent and -Independent Effects
Authors: Vergouwen Mervyn D.I. , Ilodigwe Don , Macdonald R. Loch
Published: February 2011

Background and Purpose—

The pathogenesis of delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage remains incompletely understood. It is generally assumed that it is caused by angiographic vasospasm. Our aim was to clarify the relationship among angiographic vasospasm, neurological worsening, cerebral infarction, and poor outcome and to investigate whether cerebral infarction also contributes to poor outcome by vasospasm-independent effects.

Methods—

This exploratory analysis used data from 413 patients included in the Clazosentan to Overcome Neurological Ischemia and Infarction Occurring After Subarachnoid Hemorrhage (CONSCIOUS-1) trial. We studied the incidence of neurological worsening, cerebral infarction, and poor outcome in patients with and without angiographic vasospasm. Path analysis implemented by structural equation modeling was performed to determine direct and indirect path coefficients.

Results—

Of the 194 patients with moderate to severe vasospasm, 43% had neurological worsening of any cause, 20% had cerebral infarction, and 46% poor outcome. Path coefficients for direct effects on poor outcome were 0.20 for World Federation of Neurological Surgeons Grade 4 to 5, 0.13 for history of hypertension, 0.19 for angiographic vasospasm, 0.16 for neurological worsening, and 0.11 for new cerebral infarction. Cerebral infarction contributed to poor outcome by vasospasm-dependent and -independent effects.

Conclusions—

Our data show that the majority of patients with moderate to severe angiographic vasospasm did not have neurological worsening of any cause or cerebral infarction. Besides, cerebral infarction also has a direct effect on outcome independent of angiographic vasospasm. This suggests that other coexisting factors might be involved in the pathogenesis of delayed cerebral ischemia, which should also be an important research target to improve outcome after subarachnoid hemorrhage.
Age-Dependent Susceptibility to Infarct Growth in Women
Authors: Gokcay Figen , Arsava Ethem Murat , Baykaner Tuna , Vangel Mark , Garg Priya , Wu Ona , Singhal Aneesh B. , Furie Karen L. , Sorensen A. Gregory , Ay Hakan
Published: February 2011

Background and Purpose—

It is not known if there is a relationship between gender and tissue outcome in human ischemic stroke. We sought to identify whether the proportion of initially ischemic to eventually infarcted tissue was different between men and women with ischemic stroke.

Methods—

We studied 141 consecutive patients with acute ischemic stroke who had a baseline MRI obtained within 12 hours of symptom onset, a follow-up imaging on Day 4 or later, and diffusion-weighted imaging/mean transmit time mismatch on initial MRI. Lesion growth was calculated as percentage of mismatch tissue that underwent infarction on follow-up (percentage mismatch lost). Multivariable analyses explored the effect of gender and other predictors of tissue outcome on percentage mismatch lost.

Results—

There was no difference in median percentage mismatch lost between men (19%) and women (11%;
P
=0.720). There was, however, an interaction between gender and age; median percentage mismatch lost was 7% (0% to 12%) in women and 18% (1% to 35%) in men younger than the population median (71 years,
P
=0.061). The percentage mismatch lost was not different between men and women ≥71 years old (25% in both groups). The linear regression model revealed gender (
P
=0.027) and the interaction between age and gender (
P
=0.023) as independent predictors of percentage mismatch lost.

Conclusions—

There is an age-by-gender interaction in tissue outcome after ischemic stroke; brain infarcts in women <70 years grow approximately 50% less than infarcts in their male counterparts. These findings extend the well-known concept that there is a differential age-by-gender effect on stroke incidence, mortality, and functional outcome to the tissue level.
Ethnicity and Functional Outcome After Stroke
Authors: McNaughton Harry , Feigin Valery , Kerse Ngaire , Barber P. Alan , Weatherall Mark , Bennett Derrick , Carter Kristie , Hackett Maree , Anderson Craig
Published: February 2011

Background and Purpose—

There is limited information on the influence of ethnicity on functional outcome after stroke. We examined functional outcomes among European New Zealanders, Māori, Pacific, and Asian people 6 months after stroke in a population-based context.

Methods—

This was a prospective incidence and 6-month outcomes study of all new stroke patients (excluding subarachnoid hemorrhage) that occurred over 1 year in a defined geographical area in Auckland, New Zealand, during 2002 to 2003. Ethnicity was self-defined. Outcome measures included the Frenchay Activities Index, 36-item Short Form questionnaire, independence, death, composite of death and dependence, and living situation.

Results—

Functional measures were available in 1127 patients 6 months after stroke. Frenchay Activities Index scores were associated with ethnicity on both univariable and multivariable analysis, with Asian and Pacific people having worse scores. Physical Component Summary score of the 36-item Short Form was associated with ethnicity on univariable (scores for Pacific, Māori, and Asian people were higher than those for Europeans) but not multivariable analysis. Asian people were less likely to be dead compared to Europeans, and Pacific people were more likely to be dependent on others for help than Europeans. Pacific people were more likely to be dead or dependent than Europeans. Asian and Pacific people were more likely to be living at home than Europeans.

Conclusions—

Ethnicity was associated independently with functional outcomes. The association was attenuated when adjusted for stroke severity and other covariates. The direction of the relationship was not consistent between measures for individual ethnic groups.
The Functional Benefits of Tilt Adaptation
Authors: Kristjánsson Árni
Published: February 2011

Many have argued that effects of adaptation, such as aftereffects from motion or tilt, reflect that the visual system hones its responses in on the characteristics of the adapting stimulus. This view entails that on average, the discrimination of the characteristics of an adapting stimulus should become easier as viewing time increases since the variation in the response gradually adapts to the range and variation in the stimulus. Here this was tested for adaptation to tilt. Observers viewed a Gabor patch which varied in contrast from 0 to 74% at a rate of 0.6 Hz, for 4, 8, 16 or 32 s, after which the Gabor patch changed orientation (at the point when contrast was 0). The results show that the longer the observers adapt to the dynamic Gabor, the better they become at discriminating between clockwise (CW) or counterclockwise (CCW) changes in tilt (orientation) of the same patch. Experiment 2 confirms that both the direct and indirect tilt aftereffects are seen with this contrast varying Gabor patch and Experiment 3 shows that the aftereffects are only slightly smaller than in other studies with stimuli such as lines and sinusoidal gratings. These results show that adaptation to tilt leads to better discrimination around the orientation of the adapting stimulus itself, and that discrimination performance improves steadily with increased adaptation time. The results support proposals that the visual system adjusts its response characteristics to the properties of the visual input at a given time.
Sound Location Can Influence Audiovisual Speech Perception When Spatial Attention Is Manipulated
Authors: Möttönen Riikka , Tiippana Kaisa , Sams Mikko , Puharinen Hanna
Published: February 2011

Audiovisual speech perception has been considered to operate independent of sound location, since the McGurk effect (altered auditory speech perception caused by conflicting visual speech) has been shown to be unaffected by whether speech sounds are presented in the same or different location as a talking face. Here we show that sound location effects arise with manipulation of spatial attention. Sounds were presented from loudspeakers in five locations: the centre (location of the talking face) and 45°/90° to the left/right. Auditory spatial attention was focused on a location by presenting the majority (90%) of sounds from this location. In Experiment 1, the majority of sounds emanated from the centre, and the McGurk effect was enhanced there. In Experiment 2, the major location was 90° to the left, causing the McGurk effect to be stronger on the left and centre than on the right. Under control conditions, when sounds were presented with equal probability from all locations, the McGurk effect tended to be stronger for sounds emanating from the centre, but this tendency was not reliable. Additionally, reaction times were the shortest for a congruent audiovisual stimulus, and this was the case independent of location. Our main finding is that sound location can modulate audiovisual speech perception, and that spatial attention plays a role in this modulation.
An Analytical Model of Wave Bottom Boundary Layers Incorporating Turbulent Relaxation and Diffusion Effects
Authors: Zou Qingping
Published: February 2011

To calculate the effects of turbulent relaxation on oscillatory turbulent boundary layers, a viscoelastic term is added to an eddy viscosity model. The viscoelastic term parameterizes the lag of turbulent properties in response to imposed oscillatory shear and is proportional to the ratio between the timescales of eddy dissipation and of the oscillating flow. It is found that the turbulent relaxation plays an important role in the phase variations of velocity and shear stress with elevation, and that it decreases the friction factor and the phase lead of bed shear stress over free stream velocity.

To assess the effects of turbulent diffusion in this problem, the viscoelastic model is extended by further introducing a turbulent diffusion term in the model. The comparisons between these two models indicate that turbulent diffusion significantly reduces the magnitudes of shear stress and velocity perturbation in the outer region of the boundary layer. It is also found that the effects of turbulent relaxation and diffusion increase with increasing relative roughness. As a result, the analytical solutions demonstrate an overall improvement over the eddy viscosity model in predicting the observed temporal evolution of velocity and shear stress profiles; this improvement is more distinct for rough beds than smooth beds.
Mean Three-Dimensional Circulation in the Northeast Tropical Pacific*
Authors: Kessler William S.
Published: February 2011

Historical XBT data are used to construct a mean climatology of the three-dimensional geostrophic circulation in the northeast tropical Pacific (southwest of Mexico and Central America) and are diagnosed based on linear dynamics forced with satellite scatterometer winds. Unlike the familiar central tropical Pacific, where the zonal scales are very large and the wind forcing nearly a function of latitude alone, the North Pacific east of about 120°W is strongly influenced by wind jets blowing through gaps in the Central American cordillera. The curl imposed by these wind jets imprints on the ocean, producing a distinctive pattern of thermocline topography and geostrophic currents that are consistent with the Sverdrup balance. Notably, the weakening of the North Equatorial Countercurrent near 110°W is due to the wind forcing. Given the observed stratification and wind stress curl, planetary vorticity conservation also determines the distribution of vertical velocity in the region, with about 3.5 Sv (Sv ≡ 106 m3 s−1) of upwelling through the base of the thermocline under the Costa Rica Dome. This upwelling is associated with stretching of the water column under the dome, which thereby causes the northern “Subsurface Counter Current” (SSCC or Tsuchiya Jet) to turn away from the equator; about half the transport of the SSCC upwells through the thermocline via this mechanism. This may be part of the process by which intermediate-depth water, flowing into the Pacific from the south, is brought to the surface and into the Northern Hemisphere.
Balanced Ocean-Data Assimilation near the Equator
Authors: Burgers Gerrit , Balmaseda Magdalena A. , Vossepoel Femke C. , van Oldenborgh Geert Jan , van Leeuwen Peter Jan
Published: February 2011

The question is addressed whether using unbalanced updates in ocean-data assimilation schemes for seasonal forecasting systems can result in a relatively poor simulation of zonal currents. An assimilation scheme, where temperature observations are used for updating only the density field, is compared to a scheme where updates of density field and zonal velocities are related by geostrophic balance. This is done for an equatorial linear shallow-water model. It is found that equatorial zonal velocities can be detoriated if velocity is not updated in the assimilation procedure. Adding balanced updates to the zonal velocity is shown to be a simple remedy for the shallow-water model. Next, optimal interpolation (OI) schemes with balanced updates of the zonal velocity are implemented in two ocean general circulation models. First tests indicate a beneficial impact on equatorial upper-ocean zonal currents.
Thermohaline and Wind Forcing of a Circumpolar Channel withBlocked Geostrophic Contours
Authors: Borowski Daniel , Gerdes Rüdiger , Olbers Dirk
Published: February 2011

The Antarctic Circumpolar Current is governed by unique dynamics. Because the latitude belt of Drake Passage is not zonally bounded by continents, the Sverdrup theory does not apply to the Antarctic Circumpolar Current. However, most of the geostrophic contours are blocked at Drake Passage, which provides an important dynamic constraint for the vorticity equation of the depth averaged flow.

This study addresses the effects of thermohaline and wind forcing on the large-scale transport of a circumpolar current with blocked geostrophic contours. Various numerical experiments with three different idealized model geometries were conducted. Based on the results and theoretical arguments, the authors promote an indirect wind effect on the circumpolar current: while the direct effects of the wind in driving the circumpolar current through a vertical transfer of the applied wind stress are of minor importance, the wind does substantially influence the circumpolar current transport through its effects on the density field.

This indirect wind effect is discussed in two steps. First, at the latitudes of the circumpolar current and longitudes where the geostrophic contours are blocked, the meridional gradient of the mass transport streamfunction is to leading order balanced by the meridional gradient of the baroclinic potential energy. This balance implies that the total transport is to leading order baroclinic and that the deep transport is small. For this statement, some theoretical arguments are offered. Second, a simplified analytical model is used to obtain the distribution of the baroclinic potential energy. Assuming an advective–diffusive balance for the densities in the deep downwelling northern branch of the Deacon cell, this model reproduces the qualitative dependence of the circumpolar current transport on the imposed wind and thermohaline forcing as well as on the turbulent diffusivities.
On Determining the Onset and Strength of Breaking for Deep Water Waves. Part I: Unforced Irrotational Wave Groups
Authors: Song Jin-Bao , Banner Michael L.
Published: February 2011

Finding a robust threshold variable that determines the onset of breaking for deep water waves has been an elusive problem for many decades. Recent numerical studies of the unforced evolution of two-dimensional nonlinear wave trains have highlighted the complex evolution to recurrence or breaking, together with the fundamental role played by nonlinear intrawave group dynamics. In Part I of this paper the scope of two-dimensional nonlinear wave group calculations is extended by using a wave-group-following approach applied to a wider class of initial wave group geometries, with the primary goal of identifying the differences between evolution to recurrence and to breaking onset. Part II examines the additional influences of wind forcing and background shear on these evolution processes.

The present investigation focuses on the long-term evolution of the maximum of the local energy density along wave groups. It contributes a more complete picture, both long-term and short-term, of the approach to breaking and identifies a dimensionless local average growth rate parameter that is associated with the mean convergence of wave-coherent energy at the wave group maximum. This diagnostic growth rate appears to have a common threshold for all routes to breaking in deep water that have been examined and provides an earlier and more decisive indicator for the onset of breaking than previously proposed breaking thresholds. The authors suggest that this growth rate may also provide an indicative measure of the strength of wave breaking events.
Equatorial Solitary Waves. Part V: Initial Value Experiments, Coexisting Branches, and Tilted-Pair Instability
Authors: Boyd John P.
Published: February 2011

A series of high-resolution numerical experiments, augmented by theory, to further explore the dynamics of equatorial dipole vortices (Rossby solitary waves) is performed. When the amplitude is sufficiently large so that the vortices trap fluid internally, the solitary waves for a given phase speed are not unique. The potential vorticity–streak function (q–Ψ) relationship is everywhere linear for one branch, but highly nonlinear in the recirculation region for the second branch. Westward-traveling vortex pairs are highly unstable on the midlatitude beta plane, but the equatorial wave guide stabilizes vortex pairs that straddle the equator, even when given a strong initial tilt. As discovered by Williams and Wilson and explained theoretically by Boyd, the author confirms that higher latitudinal mode solitary waves are weakly nonlocal through radiation of sinusoidal Rossby waves of lower latitudinal mode number. The amplitude and wavelength of the radiation are in good agreement with nonlocal soliton theory.

It is sometimes said that the great discovery of the nineteenth century was that the equations of nature were linear, and the great discovery of the twentieth century is that they are not.—Thomas Körner, Fourier Analysis (1988, p. 99)
Effects of Wind on Convection in Strongly and Weakly Baroclinic Flows with Application to the Labrador Sea*
Authors: Straneo Fiammetta , Kawase Mitsuhiro , Pickart Robert S.
Published: February 2011

Large buoyancy loss driving deep convection is often associated with a large wind stress that is typically omitted in simulations of convection. Here it is shown that this omission is not justified when overturning occurs in a horizontally inhomogeneous ocean. In strongly baroclinic flows, convective mixing is influenced both by the background horizontal density gradient and by the across-front advection of buoyancy due to wind. The former process—known as slantwise convection—results in deeper convection, while the effect of wind depends on the relative orientation of wind with respect to the baroclinic front. For the case of the Labrador Sea, wintertime winds act to destabilize the baroclinic Labrador Current causing a buoyancy removal roughly one-third as large as the air–sea buoyancy loss. Simulations using a nonhydrostatic numerical model, initialized and forced with observed fields from the Labrador Sea, show how the combination of wind and lateral gradients can result in significant convection within the current, in contrast with previous ideas. Though the advection of buoyancy due to wind in weakly baroclinic flows is negligible compared to the surface buoyancy removal typical of convective conditions, convective plumes are substantially deformed by wind. This deformation, and the associated across-front secondary circulation, are explained in terms of the vertical advection of wind-generated vorticity from the surface boundary layer to deeper depths. This mechanism generates vertical structure within the convective layer, contradicting the historical notion that properties become vertically homogenized during convection. For the interior Labrador Sea, this mechanism may be partly responsible for the vertical variability observed during convection, which modeling studies have until now failed to reproduce.
Internal Waves and Turbulence in the Upper Central Equatorial Pacific: Lagrangian and Eulerian Observations
Authors: Lien R-C. , D'Asaro E. A. , McPhaden M. J.
Published: February 2011

In the shear stratified flow below the surface mixed layer in the central equatorial Pacific, energetic near-N (buoyancy frequency) internal waves and turbulence mixing were observed by the combination of a Lagrangian neutrally buoyant float and Eulerian mooring sensors. The turbulence kinetic energy dissipation rate ε and the thermal variance diffusion rate χ were inferred from Lagrangian frequency spectral levels of vertical acceleration and thermal change rate, respectively, in the turbulence inertial subrange. Variables exhibiting a nighttime enhancement include the vertical velocity variance (dominated by near-N waves), ε, and χ. Observed high levels of turbulence mixing in this low-Ri (Richardson number) layer, the so-called deep-cycle layer, are consistent with previous microstructure measurements. The Lagrangian float encountered a shear instability event. Near-N waves grew exponentially with a 1-h timescale followed by enhanced turbulence kinetic energy and strong dissipation rate. The event supports the scenario that in the deep-cycle layer shear instability may induce growing internal waves that break into turbulence. Superimposed on few large shear-instability events were background westward-propagating near-N waves. The floats' ability to monitor turbulence mixing and internal waves was demonstrated by comparison with previous microstructure measurements and with Eulerian measurements.
Energy Levels, Phase, and Amplitude Modulation of the Baroclinic Tide off Hawaii
Authors: Chiswell Stephen M.
Published: February 2011

Inverted echo sounder data from Station Aloha north of Oahu, Hawaii, are used to determine the absolute energy levels and time-varying nature of the first-mode baroclinic tide north of Hawaii. The semidiurnal tide amplitude and phase are modulated with 60–120 day periodicity, which indicates interaction between the baroclinic tide and intra-annual mesoscale variability seen off Hawaii. Close to the presumed generation site, there is less phase modulation, and amplitude modulation is uncorrelated with the far-field variability. These results are consistent with a model of phase-locked generation, together with phase and amplitude distortion during propagation. The sense of the amplitude modulation is opposite to that previously observed at decadal timescales. Semidiurnal energy flux at Station Aloha ranges from 2.2 to 8.0 kW m−1, with a mean value of 4.4 kW m−1.
Long Rossby Wave Basin-Crossing Time and the Resonance of Low-Frequency Basin Modes
Authors: Primeau François
Published: February 2011

The ability of long-wave low-frequency basin modes to be resonantly excited depends on the efficiency with which energy fluxed onto the western boundary can be transmitted back to the eastern boundary. This efficiency is greatly reduced for basins in which the long Rossby wave basin-crossing time is latitude dependent.

In the singular case where the basin-crossing time is independent of latitude, the amplitude of resonantly excited long-wave basin modes grows without bound except for the effects of friction. The speed of long Rossby waves is independent of latitude for quasigeostrophic dynamics, and the rectangular basin geometry often used for theoretical studies of the wind-driven ocean circulation is such a singular case for quasigeostrophic dynamics.

For more realistic basin geometries, where only a fraction of the energy incident on the western boundary can be transmitted back to the eastern boundary, the modes have a finite decay rate that in the limit of weak friction is independent of the choice of frictional parameters. Explicit eigenmode computations for a basin geometry similar to the North Pacific but closed along the equator yield basin modes sufficiently weakly damped that they could be resonantly excited.
A Non-normal View of the Wind-Driven Ocean Circulation
Authors: Moore Andrew M. , Perez Cristina L. , Zavala-Garay Javier
Published: February 2011

Generalized linear stability theory is applied to the wind-driven ocean circulation in the form of a double gyre described by the barotropic quasigeostrophic vorticity equation. The development of perturbations on this circulation is considered. The circulation fields are inhomogeneous, and regions of straining flow render non-normal the tangent linear operators that describe the time evolution of perturbation energy and enstrophy. When the double-gyre circulation is asymptotically stable, growth of perturbation energy and enstrophy is still possible due to linear interference of its nonorthogonal eigenmodes. The sources and sinks of perturbation energy and enstrophy associated with the interference process are traditionally associated with the interaction of perturbation stresses with the mean flow. These ideas are used to understand the response of an asymptotically stable double-gyre circulation to stochastic wind stress forcing. Calculation of the optimal forcing patterns (stochastic optimals) reveals that much of the stochastically induced variability can be explained by one pattern. Variability induced by this pattern is maintained by long and short Rossby waves that interact with the western boundary currents, and perturbation growth occurs through barotropic processes. The perturbations that maintain the stochastically induced variance in this way have a large projection on some of the most non-normal, least-damped eigenmodes of the double-gyre circulation.

Perturbation growth in nonautonomous and asymptotically unstable systems is also considered in the same framework. The Lyapunov vectors of unstable flows are found to have a large projection on some of the most non-normal, least-damped eigenmodes of the time mean circulation.
The Stabilization of the Thermohaline Circulation by the Temperature–Precipitation Feedback
Authors: Tziperman Eli , Gildor Hezi
Published: February 2011

The meridional freshwater flux in the atmosphere, and hence the strength of the hydrological cycle, undergoes variations on glacial–interglacial as well as on some shorter timescales. A significant portion of these changes to the hydrological cycle are due to the temperature–precipitation feedback according to which there is more precipitation over the higher latitudes during warm periods when the moisture holding capacity of the atmosphere is higher.

It is proposed here that this feedback may play an important role in determining the stability of the thermohaline circulation (THC). The THC stability to different parameterizations of the meridional atmospheric freshwater flux is therefore investigated using a simple box model of the ocean, atmosphere, and sea ice. It is demonstrated that parameterizations that are consistent with the temperature–precipitation feedback, and hence with the observed variations of the hydrological cycle during glacial–interglacial cycles, stabilize the THC for a wide range of forcing parameters.