bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Laboratory Model of Thermocline Depth and Exchange Fluxes across Circumpolar Fronts*
Authors: Cenedese Claudia , Marshall John , Whitehead J. A. 
Published: March 2004

Abstract
A laboratory experiment has been constructed to investigate the possibility that the equilibrium depth of a circumpolar front is set by a balance between the rate at which potential energy is created by mechanical and buoyancy forcing and the rate at which it is released by eddies. In a rotating cylindrical tank, the combined action of mechanical and buoyancy forcing builds a stratification, creating a large-scale front. At equilibrium, the depth of penetration and strength of the current are then determined by the balance between eddy transport and sources and sinks associated with imposed patterns of Ekman pumping and buoyancy fluxes. It is found that the depth of penetration and transport of the front scale like [(fwe)/g′]L and weL2, respectively, where we is the Ekman pumping, g′ is the reduced gravity across the front, f is the Coriolis parameter, and L is the width scale of the front. Last, the implications of this study for understanding those processes that set the stratification and transport of the Antarctic Circumpolar Current (ACC) are discussed. If the laboratory results scale up to the ACC, they suggest a maximum thermocline depth of approximately h = 2 km, a zonal current velocity of 4.6 cm s−1, and a transport T = 150 Sv (1 Sv ≡ 106 m3 s−1), not dissimilar to what is observed.
Aspects of the Mean Wintertime Circulation along Australia's Southern Shelves: Numerical Studies
Authors: Cirano Mauro , Middleton John F. 
Published: March 2004

Abstract
A high-resolution numerical model is used to study the mean wintertime shelf-slope circulation between the Gulfs of South Australia and the west coast of Tasmania. The mean downwelling-favorable winds for the region result in a continuous eastward coastal current (CC) extending from Cape Leeuwin to the eastern coast of Tasmania. The magnitude of the CC is generally largest over the shelf break, has speeds of more than 40 cm s−1 [transport 2.4 Sv (Sv ≡ 106 m3 s−1)], and is generally in good agreement with observations. The relative importance of the Leeuwin Current, zonal winds, and density gradients to the shelf circulation is established. Within Bass Strait, the eastward circulation is in good agreement with observations and simple models show that about 30% of the transport arises from local winds and the remainder from the CC. The total transport through the strait (0.95 Sv) is shown to be controlled by sea level on the east coast of Tasmania. A current of up to 10 cm s−1 is also found to flow from Tasmania to Esperance in the far west (transport 6.8 Sv) and to be centered within the permanent thermocline (depth 600 m) and near the shelf slope. This Flinders Current arises from the equatorward Sverdrup transport but is also fed by the “Tasman outflow” that enters the region off of the southern tip of Tasmania. A sensitivity study shows that dense water formation occurs off of Spencer Gulf and the cascade to depths of 250 m is in qualitative agreement with observations. Dense water formed near the coast can enhance the CC by up to 5 cm s−1. Suggestions for future modeling and observational studies are made.
Deep-Water Flow in the Mariana and Caroline Basins*
Authors: Siedler Gerold , Holfort Jürgen , Zenk Walter , Müller Thomas J. , Csernok Tiberiu 
Published: March 2004

Abstract
Two major water masses dominate the deep layers in the Mariana and Caroline Basins: the Lower Circumpolar Water (LCPW), arriving from the Southern Ocean along the slopes north of the Marshall Islands, and the North Pacific Deep Water (NPDW) reaching the region from the northeastern Pacific Ocean. Hydrographic and moored observations and multibeam echosounding were performed in the East Mariana and the East Caroline Basins to detail watermass distributions and flow paths in the area. The LCPW enters the East Mariana Basin from the east. At about 13°N, however, in the southern part of the basin, a part of this water mass arrives in a southward western boundary flow along the Izu–Ogasawara–Mariana Ridge. Both hydrographic observations and moored current measurements lead to the conclusion that this water not only continues westward to the West Mariana Basin as suggested before, but also provides bottom water to the East Caroline Basin. The critical throughflow regions were identified by multibeam echosounding at the Yap Mariana Junction between the East and West Mariana Basins and at the Caroline Ridge between the East Mariana and East Caroline Basins. The throughflow is steady between the East and West Mariana Basins, whereas more variability is found at the Caroline Ridge. At both locations, throughflow fluctuations are correlated with watermass property variations suggesting layer-thickness changes. The total transport to the two neighboring basins is only about 1 Sverdrup (1Sv ≡ 106 m3 s−1) but has considerable impact on the watermass structure in these basins. Estimates are given for the diapycnal mixing that is required to balance the inflow into the East Caroline Basin. Farther above in the water column, the high-silica tongue of NPDW extends from the east to the far southwestern corner of the East Mariana Basin, with transports being mostly southward across the basin.
Wave Breaking and Ocean Surface Layer Thermal Response
Authors: Mellor George , Blumberg Alan 
Published: March 2004

Abstract
The effect of breaking waves on ocean surface temperatures and surface boundary layer deepening is investigated. The modification of the Mellor–Yamada turbulence closure model by Craig and Banner and others to include surface wave breaking energetics reduces summertime surface temperatures when the surface layer is relatively shallow. The effect of the Charnock constant in the relevant drag coefficient relation is also studied.
The Relationship between Sea Surface Temperature and Thermocline Depth in the Eastern Equatorial Pacific
Authors: Zelle Hein , Appeldoorn Gerrian , Burgers Gerrit , van Oldenborgh Geert Jan 
Published: March 2004

Abstract
The time dependence of the local relation between sea surface temperature (SST) and thermocline depth in the central and eastern equatorial Pacific Ocean is analyzed for the period 1990–99, using subsurface temperature measurements from the Tropical Atmosphere–Ocean Array/Triangle Trans-Ocean Buoy Network (TAO/TRITON) buoy array. Thermocline depth anomalies lead SST anomalies in time, with a longitude-dependent delay ranging from 2 weeks in the eastern Pacific to 1 year in the central Pacific. The lagged correlation between thermocline depth and SST is strong, ranging from r &gt; 0.9 in the east to r ≈ 0.6 at 170°W. Time-lagged correlations between thermocline depth and subsurface temperature anomalies indicate vertical advection of temperature anomalies from the thermocline to the surface in the eastern Pacific. The measurements are compared with the results of forced OGCM and linear model experiments. Using model results, it is shown that the delay between thermocline depth and SST is caused mainly by upwelling and mixing between 140° and 90°W. Between 170°E and 140°W the delay has a different explanation: thermocline depth anomalies travel to the eastern Pacific, where upwelling creates SST anomalies that in turn cause anomalous wind in the central Pacific. SST is then influenced by these wind anomalies.
An Arginine Involved in GABA Binding and Unbinding But Not Gating of the GABAAReceptor
Authors: Wagner David A. , Czajkowski Cynthia , Jones Mathew V. 
Published: March 2004

GABAAreceptor function can be conceptually divided into interactions between ligand and receptor (binding) and the opening and closing of the ligand-bound channel (gating). The relationship between binding, gating, and receptor structure remains unclear. Studies of mutations have identified many amino acid residues that contribute to the GABAbinding site. Most of these studies assayed changes in GABA dose–response curves, which are macroscopic measures that depend on the interplay of many processes and cannot resolve individual microscopic transitions. Understanding the microscopic basis of binding and gating is critical, because kinetic transition rates predict how receptors will behave at synapses. Furthermore, microscopic rates are directly related to the molecular interactions underlying receptor function.Here, we focused on a residue (β2-R207) previously identified as lining the GABA-binding site that, when mutated to cysteine, greatly reduces apparent GABA affinity and was predicted to affect both binding and gating. To better understand the role of β2-R207, we expressed α1β2and α1β2-R207C receptors in human embryonic kidney 293 cells and studied receptor kinetics using fast solution applications. The mutation accelerated deactivation by 10-fold, without altering desensitization in the presence of saturating GABA. Maximum open probability and single-channel open times were also unaltered by the mutation, but the GABA-binding rate was reduced eightfold. Therefore, the effects of this mutation in a predicted binding site residue are solely attributable to changes in GABA-binding and unbinding kinetics, with no changes in channel gating. Because β2-R207 stabilizes GABA in the binding pocket, it may directly contact the GABA molecule.
The Orexin/Hypocretin System in Zebrafish Is Connected to the Aminergic and Cholinergic Systems
Authors: Kaslin Jan , Nystedt Johanna M. , Östergård Maria , Peitsaro Nina , Panula Pertti 
Published: March 2004

The orexin/hypocretin (ORX) system is involved in physiological processes such as feeding, energy metabolism, and the control of sleep and wakefulness. The ORX system may drive the aminergic and cholinergic activities that control sleep and wakefulness states because of the ORX fiber projections to the aminergic and cholinergic cell clusters. The biological mechanisms and relevance of the interactions between these neurotransmitter systems are poorly understood. We studied these systems in zebrafish, a model organism in which it is possible to simultaneously study these systems and their interactions.We cloned a zebrafish prepro-ORX gene that encodes for the two functional neuropeptides orexin-A (ORX-A) and orexin-B (ORX-B). The prepro-ORX gene of the zebrafish consisted of one exon in contrast to mammals. The sequence of the ORX-A peptide of the zebrafish was less conserved than the ORX-B peptide compared with other vertebrates. By usingin situhybridization and immunohistochemistry, we found that the organization of the ORX system of zebrafish was similar to the ORX system in mammals, including a hypothalamic cell cluster and widespread fiber projections. The ORX system of the zebrafish showed a unique characteristic with an additional putatively ORX-containing cell group. The ORX system innervated several aminergic nuclei, raphe, locus ceruleus, the mesopontine-like area, dopaminergic clusters, and histaminergic neurons. A reciprocal relationship was found between the ORX system and several aminergic systems. Our results suggest that the architecture of these neurotransmitter systems is conserved in vertebrates and that these neurotransmitter systems in zebrafish may be involved in regulation of states of wakefulness and energy homeostasis by similar mechanisms as those in mammals.
Inhibitory Control at a Synaptic Relay
Authors: Awatramani Gautam B. , Turecek Rostislav , Trussell Laurence O. 
Published: March 2004

The mammalian medial nucleus of the trapezoid body (MNTB) harbors one of the most powerful terminals in the CNS, the calyx of Held. The mechanisms known to regulate this synaptic relay are relatively ineffective. Here, we report the presence of a remarkably robust and fast-acting glycinergic inhibitory system capable of suppressing calyceal transmission.Evoked glycinergic IPSCs were relatively small in 2-week-old rats, an age by which calyceal maturation has reportedly neared completion. However, by postnatal day 25 (P25), glycinergic transmission had undergone a vigorous transformation, resulting in peak synaptic conductances as high as 280 nS. These are comparable with glutamatergic conductances activated by calyceal inputs. Decay kinetics for IPSCs were severalfold faster than for glycinergic synaptic events reported previously. At physiological temperatures in P25 rats, IPSCs decayed in ∼1 msec and could be elicited at frequencies up to 500 Hz. Moreover, EPSPs triggered by glutamatergic signals derived from the calyx or simulated by conductance clamp were suppressed when preceded by simulated glycinergic IPSPs. The matching of excitatory transmission in the calyx of Held by a powerful, precision inhibitory system suggests that the relay function of the MNTB may be rapidly modified during sound localization.
Mechanisms of Insulin Signal Transduction
Authors: Garvey W. Timothy 
Published: March 2004

AbstractThe peptide hormone insulin is secreted from pancreatic β‐cells, binds to cell surface receptors, and exerts a broad spectrum of anabolic effects in multiple tissues. In mediating its pleiotrophic actions, insulin engages multiple signal transduction, pathways that affect the expression and posttranslational modification of proteins, and regulates enzymatic pathways, subcellular protein localization, and the activation state of membrane transport systems. There are three major steps that provide for divergence of insulin signal transduction, leading to different functional effects: (i) the family of insulin receptor substrate (IRS) docking molecules, (ii) activation of phosphatidylinositide 3 (PI‐3) kinase, and (iii) activation of Akt/protein kinase B (PKB). Stimulation of the glucose transport system involves activation of two parallel pathways, the IRS/PI‐3 kinase pathway (resulting in activation of Akt/PKB and PKC‐λ/ζ) and the CAP/Cbl/TC10 pathway, that then interact with systems regulating trafficking of GLUT‐4‐containing vesicles and the cytoskeleton. Furthermore, multiple mechanisms modulate insulin signal transduction by affecting the serine/threonine phosphorylation state of tyrosine kinase substrates and phosphoinositides, and the tyrosine phosphorylation state of insulin receptors and IRS molecules. Thus, promulgation of the insulin action is most accurately viewed as a flexible pattern of network interactions involving a web of signal molecule cascades and effector systems. Complex patterns of interactions among signal and effector systems allow for greater plasticity in adaptive responses, and present an increasing number of targets for therapeutic intervention in treating human insulin resistance.
Measuring Insulin ActionIn Vivo
Authors: Bergman Richard N. , Hücking Katrin , Watanabe Richard M. 
Published: March 2004

AbstractThe goal to accurately measure insulin sensitivity (i.e., “insulin resistance”) in patients remains an important goal. Insulin resistance is a risk factor for a plethora of chronic diseases (diabetes cardiovascular disease, hypertension, colon cancer). To study these diseases and to intervene early in their pathogenesis requires that we quantify risk factors and insulin resistance is one important candidate.To accurately measure sensitivity it is important to use a method that observes in some fashion the metabolic effect of insulin given intravenously. Thus, the glucose clamp and the minimal model are accurate and reproducible methods. One must remain vigilant regarding limitations of these methods. However, they may be applied with confidence under a wide variety of conditions. Unfortunately it is not possible to recommend simpler (i.e. surrogate) methods that can be applied with confidence. While it might be appropriate to use fasting insulin to reflect insulin resistance in patients without any degree of β‐cell failure, it is usually not possible to determinea prioriwhether any such defect exists. Thus, one can report fasting insulin simply as aqualitative reflectionof insulin resistance. Indices, which also include glucose, appear to add little to the fasting insulin itself. If β‐cell failure progresses, the interpretation of fasting insulinper sebecomes impossible. Finally, as of this writing it is not possible to recommend insulin sensitivity measures calculated from the oral glucose tolerance test due to confounds related to differences in gastric emptying, β‐cell function, and glucose effectiveness. Clearly, studies to identify and validate simpler methods to assess insulin action accurately in the intact subject should be continued.
Insulin ActionsIn Vivo: Glucose Metabolism
Authors: Ferrannini Ele , DeFronzo Ralph A. 
Published: March 2004

AbstractCatheter techniques and tracer methodology employed for the study of glucose metabolismin vivoare presented in detail in order to define concepts, qualify interpretation, and outline limitations. Origin, total‐body, and regional uptake and main intracellular routes of disposition for circulating glucose are described separately for the basal and fed state, with punctual indication of the action of insulin on these processes. The physiology of the glucose/insulin system is recapitulated into points of clinical interest.
Insulin Regulation of Ketone Body Metabolism
Authors: Ciaraldi Theodore P. , Henry Robert R. 
Published: March 2004

AbstractThe overarching concern in the hormonal control of ketone body metabolism is the insulin level. In circumstances where insulin levels are relatively high, such as the fed state, both substrate (free fatty acid, [FFA]) availability and FFA oxidation are suppressed, directing FFA to storage and employing glucose to meet the energy needs of the body. In situations of relative insulin deficiency, such as starvation or type I diabetes, FFA oxidation is increased, driving the production of alternative energy‐producing substrates, ketone bodies, for use by the brain, as well as peripheral tissues. Insulin influences the activity of three key processes: FFA availability (lipolysis), ketone body production (ketogenesis), and disposal in peripheral tissues. All of these processes can be altered in pathophysiologic conditions such as type 1 and type 2 diabetes, obesity, starvation, and hyperthyroidism. The key control point is carnitine palmitoyltransferase‐I (CPT‐I), which mediates the passage of long chain fatty acyl coenzyme A (FA‐CoA) esters across the outer mitochondrial membrane, prior to oxidation or ketogenesis. Insulin regulates CPT‐I both at the level of gene transcription and by influencing the affinity for allosteric modulators. Regulation of hepatic CPT‐I expression or activity holds potential significance as an approach for controlling hyperglycemia and insulin resistance.
Diabetes Secondary to Acquired Disease to the Pancreas
Authors: Prato Stefano Del , Coppelli Alberto , Tiengo Antonio 
Published: March 2004

AbstractSecondary diabetes is a condition of hyperglycemia which develops after the destruction of the pancreatic tissue by an acquired disease with subsequent impairment of exocrine and endocrine pancreatic functions. In general, any pathologic process of the pancreatic acinar tissue may results in an insult to its endocrine component, leading to some degree of hormone insufficiency. This condition was first described in 1788 by Sir Thomas Cawley, but it was soon appreciated that hyperglycemia can ensues acute and chronic pancreatitis, partial and total pancreatectomy, neoplasia as well as systemic processes involving the pancreas, such as hemochromatosis and cystic fibrosis. The Expert Committee on the Diagnosis and Classification of Diabetes Mellitus of the American Diabetes Association has identified these forms of diabetes as “diabetes secondary to diseases of the exocrine pancreas.” The new diagnostic criteria for diabetes introduced by the ADA and WHO Expert Committees are likely to influence the prevalence of diabetes in patients with diseases of the exocrine pancreas, but direct assessment using the new criteria is still too scanty. When the 1979 NDDG and 1985 WHO criteria are used, it can be calculated that diabetes secondary to disease of the exocrine pancreas represents, approximately, 0.5% of all cases of diabetes mellitus. Its frequency is likely to be twice as high in populations with heavy alcohol consumption. In the tropics, the prevalence of diabetes secondary to fibrocalculous pancreatitis can be as high as 10–20%. At variance with the selective B‐cell destruction occurring in type 1 diabetes, pancreatic diabetes is characterized by concomitant destruction of all endocrine cells of the islet of Langherans. The dual insulin–glucagon deficit is responsible for many of the metabolic and clinical manifestation of this form of diabetes, including lower risk for ketoacidosis and more frequent and severe hypoglycemic episodes. Since the late 1950s, the general idea has been that secondary diabetes was not associated with vascular complications. However, with the improved life expectancy of these patients during the past few years, a similar prevalence of retinopathy and microalbuminuria has been described in pancreatic and type 1 diabetes mellitus. The knowledge of the hormonal, metabolic, and clinical features of these forms of diabetes is essential in defining the most appropriate therapeutic strategies.
Dietary Management of Diabetes Mellitus in Europe and North America
Authors: Mann J.I. , Lewis-Barned N.J. 
Published: March 2004

AbstractThe Japanese diet is widely known to be a healthy one, with a low risk for causing cardiovascular disease. Historically rooted, Japanese gastronomic culture is unique, and includes a wide variety of foodstuffs, original flavoring recipes, and fermentation methods. A distinctive Food Guide Pyramid for Japanese people and a meal log chart, evaluating eight major treatment assessments, have been created to aid dietary guidance. The results are represented diagrammatically in this chapter, with each of the treatment assessments being scored. Straightforward to understand, this guidance is stress‐free for the patient and helps ensure that the patient follows the appropriate dietary regimen.Since diabetes treatment not only involves blood glucose level monitoring, but also the evaluation of the disease's complications course, the treatment assessments are made on a 3–6‐months timeframe. The case study results indicate that the dietary guidance based on the Food Guide Pyramid is useful and beneficial for treatment of the disease.
Dietary Management of Diabetes Mellitus in Sub‐Saharan Africa
Authors: Steyn Nelia P. , Levitt Naomi S. 
Published: March 2004

AbstractThis chapter provides information about prevailing dietary practices in sub‐Saharan Africa as a background to published data on the dietary management of diabetes in the region. It highlights the finding that there is a paucity of practical and culturally relevant guidelines for people with diabetes. Recommendations in this regard are usually based on those emanating from Europe and the USA that are reliant upon interpretation by a dietitian; however, there are few dietitians in the region. Furthermore, other health workers who have not received nutrition training give the majority of dietary information. The chapter describes the available published data on dietary knowledge and practices for people with diabetes in the region and provides some examples of relevant and affordable meal plans as well as practical advice for health professionals. Suggestions are also given for overcoming some of the health systems barriers currently preventing dietary management from achieving its potential.