bluuebunny/crossref_metadata_2025 huggingface dataset:
Expression of Vascular Endothelial Growth Factor and Presence of Angiovascular Cells in Tissues from Different Thyroid Disorders
Authors: Itoh Asako , Iwase Katsumi , Jimbo Shin , Yamamoto Haruo , Yamamoto Naoki , Kokubo Masahiro , Senda Takao , Nakai Akira , Nagagasaka Akio , Nagasaka Takaaki , Hibi Yatsuka , Seko Teppei
Published: December 2009

Background

Vascular endothelial growth factor (VEGF) is involved in tumor angiogenesis and other pathophysiological processes.

Materials and methods

We studied the localization of VEGF in human thyroid tissues to clarify its involvement in proliferative processes in a variety of thyroid disorders. Immunohistochemical analysis using purified rabbit polyclonal anti‐human VEGF or anti‐human CD34 antibody and a streptavidin–biotin peroxidase complex detection system was performed on 58 tissue specimens from 53 patients with different thyroid disorders and 5 normal thyroid glands.

Results

Vascular endothelial growth factor was not detected in normal thyroid follicular cells. However, some thyroid tumor cells expressed VEGF in the cytoplasm (papillary carcinoma, 10/18; follicular carcinoma, 1/3; medullary carcinoma, 2/2; follicular adenoma, 3/11; adenomatous goiter, 2/4). In benign follicular adenoma and adenomatous goiter, weak expression of VEGF was found in small areas of the tumor, whereas in malignant thyroid tumors, it was strongly expressed in many cells. However, VEGF was not expressed in anaplastic carcinoma, malignant lymphoma, or Graves’ disease. Angiovascular cells stained with CD34 antibody in tissues from different thyroid disorders reflected statistically significant differences in papillary carcinoma, follicular adenoma, and Graves’ disease compared with normal thyroids, and such cells showed a trend toward increases in medullary carcinoma and adenomatous goiter. In contrast, low vascularity was observed in anaplastic carcinoma, malignant lymphoma, and follicular carcinoma.

Conclusions

Because VEGF probably functions as a hypoxia‐inducible angiogenic factor, overexpression of this mediator, concomitant with hypervascularity, may be induced more strongly in malignant thyroid tumors, which need more oxygen to proliferate, than in benign follicular tumors. However, neither VEGF nor CD34 was expressed in anaplastic thyroid carcinoma, which is an extremely poorly differentiated malignant tumor. CD34 but not VEGF was expressed in the hyperplastic thyroid tissues of Graves’ disease composed of nontransformed cells. Thus, the expression of VEGF concomitant with CD34 is suggested to reflect both the transformation and differentiation state of malignant tumors.
Central Lymph Node Metastasis: Is It a Reliable Indicator of Lateral Node Involvement in Papillary Thyroid Carcinoma?
Authors: Xiao Gui‐Zhou , Gao Li
Published: December 2009

Background

The purpose of the present study was to evaluate the reliability of central lymph node metastases in predicting lateral node involvement in papillary thyroid carcinoma (PTC).

Methods

This retrospective study consists of 121 patients with PTC who underwent ipsilateral selective neck dissection. The quantitative relationship between central and lateral lymph node metastases (LNM) was analyzed.

Results

A total of 86 patients (71.1%) had pathologically proven LNM; 55 patients had LNM in both the central and lateral compartments, 22 patients had only central LNM, and 9 patients had skip metastasis to lateral nodes. The sensitivity of central node involvement to predict lateral LNM was 85.9%, the specificity was 61.4%. The presence of two or more positive central nodes was associated with a high incidence of lateral LNM (70–93.3%), when compared with none (20.5%) or one (47.4%) positive central node.

Conclusions

The node status of the central compartment is moderately predictive of that of lateral compartment. The presence of two or more positive central nodes may be of value in predicting lateral node involvement.
Excellent Prognosis of Patients with Solitary T1N0M0 Papillary Thyroid Carcinoma Who Underwent Thyroidectomy and Elective Lymph Node Dissection Without Radioiodine Therapy
Authors: Ito Yasuhiro , Masuoka Hiroo , Fukushima Mitsuhiro , Inoue Hiroyuki , Kihara Minoru , Tomoda Chisato , Higashiyama Takuya , Takamura Yuuki , Kobayashi Kaoru , Miya Akihiro , Miyauchi Akira
Published: December 2009

Background

The extent of surgery for papillary carcinoma significantly differs between western countries and Japan. Almost routine total thyroidectomy with radioiodine ablation therapy has been performed in western countries, whereas limited thyroidectomy has been adopted in Japan, especially for low‐risk cases. In this study, the prognosis of patients with solitary papillary carcinoma measuring 2 cm or less without massive extrathyroid extension, clinically apparent lymph node metastasis or distant metastasis at diagnosis (T1N0M0 in the UICC TNM classification) was investigated to elucidate the appropriate extent of surgery for these patients.

Methods

We investigated the prognosis of 2,638 patients with solitary T1N0M0 papillary carcinoma who underwent initial surgery between 1987 and 2004. Total or near total thyroidectomy was performed for 1,037 patients and the remaining 1,601 patients underwent more limited thyroidectomy. Elective central node dissection was performed for 2,511 patients, accounting for 96%, and 1,545 (59%) also underwent prophylactic lateral node dissection. Radioiodine ablation therapy was performed only for three patients.

Results

The 10‐year disease‐free survival (DFS) rate of our series was 97%. To date, recurrence was observed in 62 patients (2%) and 41 showed recurrence to the regional lymph nodes. Seventeen of 1,601 patients who received limited thyroidectomy (1%) showed recurrence to the remnant thyroid. Pathological nodal‐positive patients showed a worse DFS, but the 10‐year DFS rate was still high at 96%. Patients with total or near total thyroidectomy had a better DFS, but the difference disappeared if recurrence to the remnant thyroid was excluded. A number needed to treat (NNT) for total or near total thyroidectomy over hemithyroidectomy was 83 to prevent 1 recurrence.

Conclusions

These findings suggest that solitary T1N0M0 patients have an excellent prognosis when they undergo thyroidectomy and elective lymph node dissection without radioiodine therapy. Regarding the extent of thyroidectomy, hemithyroidectomy is adequate for these patients, if a 1% risk of recurrence to the remnant thyroid is accepted.
Oncocytic Cell Tumors of the Thyroid: Factors Predicting Malignancy and Influencing Prognosis, Treatment Decisions, and Outcomes
Authors: Pisanu Adolfo , Di Chiara Barbara , Reccia Isabella , Uccheddu Alessandro
Published: December 2009

Background

The distinction between malignant and benign thyroid oncocytic cell tumors (OCTs) before and during surgery still represents a diagnostic challenge. We focused on the search for specific factors that predict malignancy and influence the prognosis of OCTs, and for their most appropriate management.

Methods

From January 1998 to May 2007, 57 patients underwent thyroidectomy in our surgical department because of OCT. A cross‐sectional study of 28 patients with carcinoma and 29 patients with adenoma was performed: demographic data, tumor characteristics, diagnostic results, patient management, postoperative, and follow‐up results were evaluated.

Results

The prevalence of malignancy was 49.1%. The mean tumor size was significantly greater for carcinomas than for adenomas (3.0 cm vs. 1.8 cm; p = 0.003). Threshold sizes of more than 3.0 cm and 4.0 cm were significant for predicting malignancy (p = 0.020 and p = 0.010, respectively). Tumor multifocality, microfollicular features, and severe cytological atypia also were significantly related to malignancy (p = 0.012 and p = 0.025, respectively). Recurrent OCT was observed in three patients with carcinoma. One patient with distant metastases died from the disease. Older age, tumor size, thyroid capsular invasion, higher TNM stage, and AMES high risk were factors significantly related to tumor recurrence. Multivariate analysis showed that larger tumor size was the only factor predictive of malignancy and influencing recurrence.

Conclusions

All OCTs should be referred to surgery because of the high prevalence of malignancy. In the case of OCTs with larger tumor size and microfollicular features with severe cytological atypia, total thyroidectomy is strongly recommended as initial treatment also in relation with the more likely aggressive biological behavior of greater tumors.
Revision Knee Arthroplasty Including Reconstruction of the Lateral Collateral Ligament by Allograft: A Case Report
Authors: Ohnsorge Jörg A. K. , Wickiewicz Thomas L. , Davis Jack , Laskin Richard S.
Published: December 2009

A 53-year-old woman presented with an unstable and painful total knee arthroplasty 6 months after the index procedure. Disruption of both collateral ligaments as a young adult and the subsequent development of traumatic arthritis required repeated surgical and extensive conservative treatment before a prosthesis was implanted. Examination disclosed marked instability of the lateral collateral ligament (LCL) and loosening of the tibial and the femoral components. Review of the MRI obtained prior to the total knee replacement revealed discontinuity of the LCL with intense scarring of the posterolateral ligament complex. Definitive management of this twofold problem was not helped by literature review, which failed to reveal a gold standard or a broad consensus as a rationale for treatment. Consequently, an individual approach to the problem was defined: A one-stage revision arthroplasty was performed using a modular non-articulated constrained prosthesis and a bone–tendon–bone allograft to reconstruct the LCL in a one-stage operation. Postoperative rehabilitation included continuous passive motion, which was begun immediately after surgery and was gradually increased to 90° of flexion. The LCL reconstruction was initially protected in a hinged knee brace and weight-bearing was initially limited to toe-touch and gradually increased over 6 weeks. Pain-free motion to 0–115° flexion was achieved at 3 months after surgery and the patient had returned to her normal activities. The 4-year-follow-up displayed a stable and functional knee with no evidence of loosening or wear.
Effect of Metal Contaminants and Antioxidants on the Oxidation Stability of the Methyl Ester of Pongamia
Authors: Sarin Amit , Arora Rajneesh , Singh N. P. , Sarin Rakesh , Sharma Meeta , Malhotra R. K.
Published: December 2009

According to the proposed National Mission on biodiesel in India, we have undertaken studies on the stability of biodiesel from tree‐borne non‐edible oil seeds like Pongamia pinnata. Neat Pongamia methyl ester (PoME) exhibited an oxidation stability (OS) of 2.54 h and research was conducted to investigate the effect of the presence of transition metals likely to be present in the metallurgy of storage tanks and barrels, on the OS of PoME. It was found that the influence of metal was detrimental to OS and was catalytic, as even small concentrations of metal contaminants showed nearly the same influence on OS as large amounts. Copper showed the strongest detrimental and catalytic effect on OS. The OS of metal‐contaminated PoME was found to increase with an increase in the dosage of antioxidant but the dosage required for copper‐contaminated PoME became approximately four times than required for neat PoME. The dependence of the OS on the type of metal showed that long‐term storage tests in different types of metal containers for examining the influence of container material on OS of biodiesel may be replaced by the significantly faster Rancimat test serving as an accelerated storage test.
Australian Oryza: Utility and Conservation
Authors: Henry Robert J. , Rice Nicole , Waters Daniel L. E. , Kasem Shabana , Ishikawa Ryuji , Hao Yin , Dillon Sally , Crayn Darren , Wing Rod , Vaughan Duncan
Published: December 2009

Australian Oryza are an understudied and underexploited genetic resource for rice improvement. Four species are indigenous: Oryza rufipogon, Oryza meridionalis, Oryza australiensis are widespread across northern Australia, whereas Oryza officinalis is known from two localities only. Molecular analysis of these wild populations is required to better define the distinctness of the taxa and the extent of any gene flow between them and rice. Limited collections of these wild populations are held in seed and DNA banks. These species have potential for domestication in some cases but also have many traits of potential value in the improvement of domesticated rice. Stress tolerance (biotic and abiotic) and grain quality characteristics in these populations may be useful.
Photodynamic antimicrobial activity of avian eggshell pigments
Authors: Ishikawa Shin-ichi , Suzuki Kazuto , Fukuda Eriko , Arihara Keizo , Yamamoto Yuji , Mukai Takao , Itoh Makoto
Published: December 2009

Pigmentation in avian eggshells appears to be associated with shell strength, temperature regulation, and camouflage. The pigments found in eggshells are mainly porphyrins, which have been utilized therapeutically as photosensitizers. Here, we examined the photoinactivation of gram‐positive (Staphylococcus aureus, Bacillus cereus) and gram‐negative bacteria (Escherichia coli, Salmonella enteritidis) by hen eggshells and their pigments. The results indicated that eggshells have a light‐dependent antimicrobial activity against gram‐positive, but not gram‐negative, bacteria. Our results indicate the possibility that the natural pigments used therapeutically have evolved in nature as a defence system.
Membrane rafting: From apical sorting to phase segregation
Authors: Coskun Ünal , Simons Kai
Published: December 2009

In this review we describe the history of the development of the raft concept for membrane sub‐compartmentalization. From its early beginnings as a mechanism for apical sorting in epithelial cells the concept has evolved to a general principle for membrane organisation. After a shaky start with crude methodology based on detergent extraction the field has become increasingly sophisticated, employing a host of different methods that support the existence of dynamic raft domains in membranes. These are composed of fluctuating nanoscale assemblies of sphingolipid, cholesterol and proteins that can be stabilized to coalesce, forming platforms that function in membrane signalling and trafficking.
Mechanisms of cross‐talk between the ubiquitin‐proteasome and autophagy‐lysosome systems
Authors: Korolchuk Viktor I. , Menzies Fiona M. , Rubinsztein David C.
Published: December 2009

The ubiquitin proteasome system (UPS) and macroautophagy (hereafter called autophagy) were, for a long time, regarded as independent degradative pathways with few or no points of interaction. This view started to change recently, in the light of findings that have suggested that ubiquitylation can target substrates for degradation via both pathways. Moreover, perturbations in the flux through either pathway have been reported to affect the activity of the other system, and a number of mechanisms have been proposed to rationalise the link between the UPS and autophagy. Here we critically review these findings and outline some outstanding issues that still await clarification.
Calcium and zinc supplementation protects lead (Pb)‐induced perturbations in antioxidant enzymes and lipid peroxidation in developing mouse brain
Authors: Prasanthi R.P. Jaya , Devi C. Bhuvaneswari , Basha D. Chand , Reddy N. Saya , Reddy G. Rajarami
Published: December 2009

Several studies have implicated oxidative stress as one of the important mechanisms of toxic effects of lead (Pb). In the present study we tested the beneficial effects of calcium (Ca2+) and zinc (Zn2+) in protecting the Pb‐induced oxidative stress in the brains of developing and adult mice. Mice were lactationally exposed to 0.2% Pb and supplemented with either calcium (Ca2+) or zinc (Zn2+) and the mitochondrial antioxidant enzymes [superoxide dismutase (SOD), xanthine oxidase (XO) and catalase (CAT)] and lipid peroxidation (LP) were analyzed in cortex, hippocampus, cerebellum and medulla of brains excised on postnatal day (PND) 14, 21, 28 and 3 months. The levels of free radicals were measured using direct Electron Paramagnetic Resonance (EPR) spectroscopy. Exposure to Pb resulted a significant decrease in the activities of SOD, XO and CAT while the LP levels were significantly increased in different brain regions. Evaluation of EPR signals and g‐values showed abundant accumulation of free radicals in different regions of the brain following Pb exposure. Interestingly the supplementation with Ca2+ or Zn2+ reversed the Pb‐induced effects on antioxidant enzymes, LP and free radical formation; however Zn2+ supplementation appeared to be more protective. These findings strongly support that zinc and calcium supplementation significantly protect the Pb‐induced oxidative stress, a major contributing factor to neurotoxicity.
Effects of a chronic exposure to a highly palatable diet and its withdrawal, in adulthood, on cerebral Na+,K+‐ATPase and plasma S100B in neonatally handled rats
Authors: da S. Benetti Carla , Silveira Patrícia P. , Matté Cristiane , Stefanello Francieli M. , Leite Marina C. , Gonçalves Carlos Alberto S. , Wyse Angela T.S. , Dalmaz Carla , Goldani Marcelo Z.
Published: December 2009

We have previously demonstrated that early environment influences the metabolic response, affecting abdominal fat deposition in adult female rats exposed to a long‐term highly caloric diet. In the present study, our goal was to verify the effects of the chronic exposure, in adulthood, to a highly palatable diet (chocolate) on cerebral Na+,K+‐ATPase activity and S100B protein concentrations, and the response to its withdrawal in neonatally handled and non‐handled rats. We measured the consumption of foods (standard lab chow and chocolate), body weight gain, S100B protein concentrations, as well as cerebral Na+,K+‐ATPase activity during chronic exposure and after chocolate withdrawal in adult female rats that had been exposed or not to neonatal handling (10 min/day, 10 first days of life). Non‐handled rats chronically exposed to chocolate exhibited increased plasma S100B levels, but there was no difference in abdominal fat S100B concentration between groups. Chronic chocolate consumption decreased Na+,K+‐ATPase activity in both amygdala and hippocampus in non‐handled, but not in handled rats, and this effect disappeared after chocolate withdrawal. Non‐handled animals also demonstrated increased frequency of head shaking in the open field after 24 h of chocolate withdrawal in comparison to handled ones. These findings suggest that neonatal handling modifies the vulnerability to metabolic and brain alterations induced by chronic exposure to a highly palatable diet in adulthood.
Organic‐rich mud on the western margin of southern Africa: Nutrient source to the Southern Ocean?
Authors: Compton John , Herbert Caren , Schneider Ralph
Published: December 2009

The biological pump plays a major role in the transfer of CO2 from the atmosphere to the deep Southern Ocean, a transfer which is largely controlled by the supply of iron and which may partially explain glacial to interglacial variations in pCO2. Analogous to the well‐documented, smaller‐scale “island mass effect,” we propose that the lateral advection of iron by south flowing intermediate waters along the southern African margin may sustain high‐productivity blooms of the Subtropical Convergence Zone (SCZ) between 10 and 70°E. We assess the present‐day interglacial (Holocene) reservoirs and fluxes of organic carbon (OC) and terrigenous mud on the western margin of southern Africa in order to estimate the potential supply of Fe to the Southern Ocean. The highly productive Benguela Upwelling System (BUS) appears to be a relatively inefficient coastal biological pump. Repeated sediment resuspension by wave and tidal energy dissipation limits OC burial to <0.2% of net primary production (NPP) in the southern BUS and to between 0.2 to 2.4% in the northern BUS. Productivity and OC‐rich mud accumulation are focused on the inner portion of the 100–200 km wide shelf which, combined with south flowing bottom currents, limits the export of OC beyond the shelf break to 1.2–8.4% of NPP. However, winnowing of 1 million tons yr−1 of clay particles and the potential early diagenetic benthic (dissolved) Fe flux may supply 10 times more Fe than is transported by dust to the open ocean biological pump of the SCZ. Lowering sea level during glacial periods disperses interglacial mud deposits off the shelf and increases particulate Fe export by as much as a factor of 4. Glacial pulses of margin export may enhance the efficiency of the subantarctic Southern Ocean biological pump and contribute to the initial as well as glacial maximum drawdown in pCO2.
Modeling gross primary production of deciduous forest using remotely sensed radiation and ecosystem variables
Authors: Jahan Nasreen , Gan Thian Yew
Published: December 2009

We explored the potential application of two remotely sensed (RS) variables, the Global Vegetation Moisture Index (GVMI) and the near‐infrared albedo (AlbedoNIR), in modeling the gross primary production (GPP) of three deciduous forests. For the Harvard Forest (deciduous) of Massachusetts, it was found that GPP is strongly correlated with GVMI (coefficient of determination, R2 = 0.60) during the growing season, and with AlbedoNIR (R2 = 0.82) throughout the year. Subsequently, a statistical model called the Remotely Sensed GPP (R‐GPP) model was developed to estimate GPP using remotely sensed radiation (land surface temperature (LST), AlbedoNIR) and ecosystem variables (enhanced vegetation index (EVI) and GVMI). The R‐GPP model, calibrated and validated against the GPP estimates derived from the eddy covariance flux tower of the Harvard Forest, could explain 95% and 92% of the observed GPP variability for the study site during the calibration (2000–2003) and the validation (2004–2005) periods, respectively. It outperformed the primary RS‐based GPP algorithm of Moderate Resolution Imaging Spectroradiometer (MODIS), which explained 80% and 77% of the GPP variability during 2000–2003 and 2004–2005, respectively. The calibrated R‐GPP model also explained 93% and 94% of the observed GPP variation for two other independent validation sites, the Morgan Monroe State Forest and the University of Michigan Biological Station, respectively, which demonstrates its transferability to other deciduous ecoregions of northeastern United States.
Lower atmosphere observations over the equatorial Indian Ocean with a shipborne lower troposphere radar during MISMO field experiment
Authors: Kawano Noriyuki , Hashiguchi Hiroyuki , Yoneyama Kunio , Fukao Shoichiro
Published: December 2009

Stationary intensive observations over the Indian Ocean (0°, 80.5°E) with the research vessel Mirai were conducted using shipborne lower troposphere radar (SB‐LTR) on the Mirai Indian Ocean Cruise for the Study of the MJO‐convection Onset field experiment from 28 October to 20 November 2006. Sea surface temperature (SST) showed large diurnal variations when there was little cloud cover, and large specific humidity was confirmed around the surface of the sea. A few days later, when small cloud clusters passed over Mirai, strong updrafts were observed by SB‐LTR up to 1.5 km altitude above the level of free convection (LFC), the mixing layer observed by SB‐LTR showed large diurnal variations, and specific humidity decreased around the surface of the sea. These results suggested that local convective instability related to large diurnal variations of SST caused large diurnal variations of the mixing layer and strong updrafts and contributed to developing cloud clusters. Super cloud clusters related to the Madden‐Julian Oscillations (MJO) proceeded eastward over Mirai between 16 and 20 November. At the same time, horizontal winds showed a large‐scale convergence, specific humidity, and the equivalent black body temperature (TBB) showed similar time‐height variations. A strong mixing layer and updrafts were also observed up to an altitude of 1.5 km using SB‐LTR, which were also above the LFC; however, large diurnal variations of the mixing layer were not confirmed. Specific humidity was relatively large around the surface of the sea, which was quite different from the results in the small cloud clusters. These results indicated that the small cloud clusters could be caused by local convective instability, but MJO convections would be correlated by large‐scale convergence.
Performance analysis and comparison of symmetrical and asymmetrical configurations of evanescent mode ridge waveguide filters
Authors: Soto P. , de Llanos D. , Boria V. E. , Tarín E. , Gimeno B. , Oñoro A. , Hidalgo I. , Padilla M. J.
Published: December 2009

In this paper, the trade‐offs between out‐of‐band performance, filter length, power‐handling capability, and insertion loss of both symmetrical and asymmetrical evanescent mode ridge rectangular waveguide filters are investigated. As a result, clear design methodologies for optimizing such performances are proposed. The developed methodologies are then applied to design several evanescent mode filters, and a complete performance analysis of the symmetrical and asymmetrical structures is performed. From the performance analysis results, the designer can choose the more appropriate filter topology and design strategy to satisfy the prescribed specifications.
Integration of nitrogen cycle dynamics into the Integrated Science Assessment Model for the study of terrestrial ecosystem responses to global change
Authors: Yang Xiaojuan , Wittig Victoria , Jain Atul K. , Post Wilfred
Published: December 2009

A comprehensive model of terrestrial N dynamics has been developed and coupled with the geographically explicit terrestrial C cycle component of the Integrated Science Assessment Model (ISAM). The coupled C‐N cycle model represents all the major processes in the N cycle and all major interactions between C and N that affect plant productivity and soil and litter decomposition. Observations from the LIDET data set were compiled for calibration and evaluation of the decomposition submodel within ISAM. For aboveground decomposition, the calibration is accomplished by optimizing parameters related to four processes: the partitioning of leaf litter between metabolic and structural material, the effect of lignin on decomposition, the climate control on decomposition and N mineralization and immobilization. For belowground decomposition, the calibrated processes include the partitioning of root litter between decomposable and resistant material as a function of litter quality, N mineralization and immobilization. The calibrated model successfully captured both the C and N dynamics during decomposition for all major biomes and a wide range of climate conditions. Model results show that net N immobilization and mineralization during litter decomposition are dominantly controlled by initial N concentration of litter and the mass remaining during decomposition. The highest and lowest soil organic N storage are in tundra (1.24 Kg N m−2) and desert soil (0.06 Kg N m−2). The vegetation N storage is highest in tropical forests (0.5 Kg N m−2), and lowest in tundra and desert (<0.03 Kg N m−2). N uptake by vegetation is highest in warm and moist regions, and lowest in cold and dry regions. Higher rates of N leaching are found in tropical regions and subtropical regions where soil moisture is higher. The global patterns of vegetation and soil N, N uptake and N leaching estimated with ISAM are consistent with measurements and previous modeling studies. This gives us confidence that ISAM framework can predict plant N availability and subsequent plant productivity at regional and global scales and furthermore how they can be affected by factors that alter the rate of decomposition, such as increasing atmospheric [CO2], climate changes, litter quality, soil microbial activity and/or increased N.
Nitrogen attenuation of terrestrial carbon cycle response to global environmental factors
Authors: Jain Atul , Yang Xiaojuan , Kheshgi Haroon , McGuire A. David , Post Wilfred , Kicklighter David
Published: December 2009

Nitrogen cycle dynamics have the capacity to attenuate the magnitude of global terrestrial carbon sinks and sources driven by CO2 fertilization and changes in climate. In this study, two versions of the terrestrial carbon and nitrogen cycle components of the Integrated Science Assessment Model (ISAM) are used to evaluate how variation in nitrogen availability influences terrestrial carbon sinks and sources in response to changes over the 20th century in global environmental factors including atmospheric CO2 concentration, nitrogen inputs, temperature, precipitation and land use. The two versions of ISAM vary in their treatment of nitrogen availability: ISAM‐NC has a terrestrial carbon cycle model coupled to a fully dynamic nitrogen cycle while ISAM‐C has an identical carbon cycle model but nitrogen availability is always in sufficient supply. Overall, the two versions of the model estimate approximately the same amount of global mean carbon uptake over the 20th century. However, comparisons of results of ISAM‐NC relative to ISAM‐C reveal that nitrogen dynamics: (1) reduced the 1990s carbon sink associated with increasing atmospheric CO2 by 0.53 PgC yr−1 (1 Pg = 1015g), (2) reduced the 1990s carbon source associated with changes in temperature and precipitation of 0.34 PgC yr−1 in the 1990s, (3) an enhanced sink associated with nitrogen inputs by 0.26 PgC yr−1, and (4) enhanced the 1990s carbon source associated with changes in land use by 0.08 PgC yr−1 in the 1990s. These effects of nitrogen limitation influenced the spatial distribution of the estimated exchange of CO2 with greater sink activity in high latitudes associated with climate effects and a smaller sink of CO2 in the southeastern United States caused by N limitation associated with both CO2 fertilization and forest regrowth. These results indicate that the dynamics of nitrogen availability are important to consider in assessing the spatial distribution and temporal dynamics of terrestrial carbon sources and sinks.
Surface‐melt driven Laurentide Ice Sheet retreat during the early Holocene
Authors: Carlson A. E. , Anslow F. S. , Obbink E. A. , LeGrande A. N. , Ullman D. J. , Licciardi J. M.
Published: December 2009

To better understand mechanisms of ice‐sheet decay, we investigate the surface mass balance of the Laurentide Ice Sheet (LIS) during the early Holocene, a period of known rapid LIS retreat. We use a surface energy‐mass balance model (EMBM) driven with conditions derived from an equilibrium atmosphere‐ocean general circulation model 9 kilo‐years ago simulation. Our EMBM indicates a net LIS surface mass balance of −0.67 ± 0.13 m yr−1, with losses primarily due to enhanced boreal summer insolation and warmer summers. This rate of loss compared to LIS volume reconstructions suggests that surface ablation accounted for 74 ± 22% of the LIS mass loss with the remaining loss likely driven by dynamics resulting in basal sliding and calving. Thus surface melting likely played a governing role in the retreat and disappearance of this ice sheet.
High resolution retrieval of liquid water vertical distributions using collocated Ka‐band and W‐band cloud radars
Authors: Huang Dong , Johnson Karen , Liu Yangang , Wiscombe Warren
Published: December 2009

The retrieval of cloud water content using dual‐frequency radar attenuation is very sensitive to error in radar reflectivity. Either a long radar dwell time or an average over many range gates is needed to reduce random noise in radar data and thus to obtain accurate retrievals – but at the cost of poorer temporal and spatial resolution. In this letter we have shown that, by using advanced mathematical inversion techniques like total variation regularization, vertically resolved liquid water content can be retrieved at an accuracy of about 0.15 gm−3 at 40 m resolution. This is demonstrated using the co‐located Ka‐band and W‐band cloud radars operated by the Atmospheric Radiation Measurement program. The liquid water path calculated from the radars agrees closely with that from a microwave radiometer, with a mean difference of 70 gm−2. Comparison with lidar observations reveals that the dual‐frequency retrieval also reasonably captures the cloud base height of drizzling clouds – something that is very difficult to determine from radar reflectivity alone.
Co‐variability of tropical cyclones in the North Atlantic and the eastern North Pacific
Authors: Wang Chunzai , Lee Sang‐Ki
Published: December 2009

In the Western Hemisphere, tropical cyclones (TCs) can form and develop in both the tropical North Atlantic (NA) and eastern North Pacific (ENP) Oceans, which are separated by the narrow landmass of Central America. Here it is shown that TC activity in the NA varies out‐of‐phase with that in the ENP on both interannual and multidecadal timescales. That is, when TC activity in the NA increases (decreases), TC activity in the ENP decreases (increases). Our analyses show that both vertical wind shear and convective instability contribute to the out‐of‐phase relationship, whereas relative humidity and vorticity variations at the lower troposphere do not seem to cause the relationship. The paper also discusses its association with the Pacific and Atlantic sea surface temperatures. An implication is that seasonal hurricane outlook can be improved by considering the NA and ENP together. It is hoped that this article will stimulate more research regarding TC activity in both the NA and ENP.
On the source of the polar wind in the polar topside ionosphere: First results from the EISCAT Svalbard radar
Authors: Ogawa Y. , Häggström I. , Buchert S. C. , Oksavik K. , Nozawa S. , Hirahara M. , van Eyken A. P. , Aso T. , Fujii R.
Published: December 2009

We present quantitative radar observations of both hydrogen ion (H+) and oxygen ion (O+) upflow in the topside polar ionosphere using measurements that were recently carried out with the EISCAT Svalbard Radar and the Reimei satellite. H+ upflow was clearly observed equatorward of the cusp above 500 km altitude. Within the cusp the H+ density was very low, and the upflow was dominated by O+ ions, but on closed field lines the H+ became the larger contributor to the upward flux above about 550 km. The total flux seemed to be conserved, and so below 550 km altitude O+ (with a small upward velocity of ∼50 m s−1) appeared to determine the upward flux which was then maintained by H+ in the topside ionosphere. We also found that the H+ density in the topside polar ionosphere was several times higher than current predictions of ionospheric models like IRI2001.
F layer postsunset height rise due to electric field prereversal enhancement: 1. Traveling planetary wave ionospheric disturbance effects
Authors: Fagundes P. R. , Bittencourt J. A. , Abalde J. R. , Sahai Y. , Bolzan M. J. A. , Pillat V. G. , Lima W. L. C.
Published: December 2009

An ionospheric sounding station is operational at Palmas (10.2°S, 48.2°W, dip latitude 5.5°S), Brazil, since 2002. Observations of F layer virtual height day‐to‐day variations during evening hours (1800 LT to 2000 LT) show a strong variability, even during geomagnetically quiet periods. From the ionospheric multifrequency virtual height variations (at 3, 4, 5, 6, 7, and 8 MHz), observed from July 2003 to May 2004, it is found that the virtual height day‐to‐day variability presents oscillations with periods of days during the evening hours. The thermospheric wind component perpendicular to the magnetic meridian (zonal wind) is one of the primary sources that generate the F region dynamo near sunset, which causes the zonal electric field prereversal enhancement (PRE) that induces the E × B vertical F layer postsunset height rise. Therefore, the planetary wave (PW) component that flows superposed on the thermospheric wind induces a traveling planetary wave ionospheric disturbance (TPWID) on the vertical F layer displacement. This indicates that the postsunset ionospheric height rise can be strongly modulated by TPWID oscillations. Our study shows that TPWIDs with periods of several days control the strength of the electric field PRE and, therefore, slowly push the F layer heights up or down, according to the TPWID phase. Also, simultaneous virtual height variations at Sao José dos Campos (low latitude) and Palmas (equatorial region) for October and November show similar behavior. This suggests that TPWID oscillation is a manifestation of atmospheric equatorial Kelvin waves that modulate the thermospheric wind.
Cluster observations of the entry layer equatorward of the cusp under northward interplanetary magnetic field
Authors: Shi Q. Q. , Zong Q.‐G. , Zhang H. , Pu Z. Y. , Fu S. Y. , Xie L. , Wang Y. F. , Chen Y. , Li L. , Xia L. D. , Liu Z. X. , Fazakerley A. N. , Reme H. , Lucek E.
Published: December 2009

Various boundary crossings in the vicinity of the high‐altitude cusp region were experienced by the Cluster spacecraft when the interplanetary magnetic field (IMF) was northward. In contrast to the southward IMF cases, in which a turbulent and diffusive entry layer is present equatorward of the cusp, a transition layer (without significant turbulence and diffusive properties) that shows clear differences in plasma parameters (sometimes step‐like profile) compared to the adjacent regions was observed. We suggest that this transition layer, which contains both magnetosheath and magnetospheric populations, is the entry layer during northward IMF conditions. This transition layer is possibly formed by dual‐lobe reconnection when the IMF is northward. The plasma property and the closed field line geometry of this layer indicate that it is possibly linked to the low‐latitude boundary layer. The width of this layer varies from 480 to 2200 km. The results support the notion that high‐latitude dual‐lobe reconnection is a potential mechanism of the transport of solar wind into the magnetosphere during northward IMF through the formation of a high‐altitude entry layer. The observations of different sublayers with evident density and temperature differences are consistent with the view that the reconnection process at the magnetopause is not steady.
F layer postsunset height rise due to electric field prereversal enhancement: 2. Traveling planetary wave ionospheric disturbances and their role on the generation of equatorial spread F
Authors: Fagundes P. R. , Abalde J. R. , Bittencourt J. A. , Sahai Y. , Francisco R. G. , Pillat V. G. , Lima W. L. C.
Published: December 2009

This paper investigates the role played by traveling planetary wave ionospheric disturbances (TPWIDs) on the modulation of the electric field prereversal enhancement (PRE) amplitude, near‐sunset hours, in the equatorial ionosphere, and their influence on the day‐to‐day equatorial spread F (ESF) variability. We show that “fresh” (ESF) day‐to‐day variability is closely related with the postsunset height rise due to the electric field PRE, and there is some indication that the altitude of 300 km may be a threshold height for the generation of fresh ESF. Observations of F layer virtual heights during evening hours (1800 LT, 1900 LT, and 2000 LT) present a strong day‐to‐day variability, even during geomagnetically quiet periods. In fact, this well‐organized variability is induced by TPWIDs‐type oscillations that push the F layer up or down according to the TPWID phase. The preliminary analysis presented here show that, when the planetary TPWID oscillations or geomagnetic activity raises the F layer around sunset hours, the occurrence of fresh ESF is increased, but when the TPWID‐type oscillations or geomagnetic activity pushes the F layer downward, the fresh ESF occurrence is reduced. Also, the TPWID phase modulated the onset time of the fresh ESF during high fresh ESF season. The modulation acts in such way that, when the TPWID phase maximizes, the fresh ESF onset time occurs earlier than when the TPWID phase minimizes and the fresh ESF onset time occurs later.
Incorporating and reporting uncertainties in fault slip rates
Authors: Zechar J. Douglas , Frankel Kurt L.
Published: December 2009

Quantitative slip rate estimates are essential to understanding crustal deformation processes and assessing seismic hazard. Computing slip rates requires two fundamental ingredients: estimates of the age of an offset landform or deposit and displacement along the fault of interest. Because both of these measures contain uncertainty, slip rates are inherently uncertain. Methods to compute and report slip rates have not been standardized, and therefore slip rate data are presented inconsistently and are frequently ambiguous; in particular, slip rate uncertainty is often insufficiently characterized. We present a rigorous probabilistic approach to computing and reporting intermediate‐ to long‐term fault slip rates; additionally, we have developed freely available software that provides standard age and displacement uncertainty models. We demonstrate the method using recent observations from the Neodani and Death Valley–Fish Lake Valley fault zones, and we compare slip rates determined using this approach with previously published results.
Mechanics of fluid‐driven fracture growth in naturally fractured reservoirs with simple network geometries
Authors: Zhang Xi , Jeffrey Robert G. , Thiercelin Marc
Published: December 2009

A numerical model has been developed for fluid‐driven opening mode fracture growth in a naturally fractured formation. The rock formation contains discrete deformable fractures, which are initially closed but conductive because of their preexisting apertures. Fluid flow that develops along fractures depends on fracture geometry defined by preexisting aperture distribution, offsets along a fracture path, and intersections of two or more fractures. The model couples fluid flow, elastic deformation, and frictional sliding to obtain the solution, which depends on the competition between fractures for permeability enhancement. The fractures can be opened by fluid pressure that exceeds the normal stress acting on them and by interactions with intersecting closed fractures experiencing Coulomb‐type frictional slip. The Newtonian fluid is assumed to flow through the conductive fractures according to a lubrication equation that relates the cube of an equivalent hydraulic aperture to fracture conductivity. The rock material is assumed to be impermeable and elastic. This paper provides the governing equations for the multiple fracture systems and the solution methods used. Flow distribution and fracture growth in conductive fracture sets are simulated for a range of geometric arrangements and hydraulic properties. Numerical results show that elastic interaction between fracture branches plays a controlling role in fluid migration, although initial apertures can give rise to a preferential fluid flow direction during the early stage. In the presence of offsets, fracture segments subject to strong compression are difficult to open hydraulically, and their resulting smaller permeability can increase overall upstream fracture pressure and opening. The patterns of fluid flow become more complicated if fractures intersect each other. A portion of injected fluid is lost into closed empty fractures that cut across the main hydraulic fracture, and this delays the pressure increases required for fracture growth past the crosscutting fracture. The nonlinear fluid loss rate depends on the geometric complexities of the fracture sets and on the fluid viscosity. Sometimes fracture growth can be accelerated by the fast fluid transport along an intersected, relatively conductive natural fracture.
Ocean variability over the Agulhas Bank and its dynamical connection with the southern Benguela upwelling system
Authors: Blanke Bruno , Penven Pierrick , Roy Claude , Chang Nicolette , Kokoszka Florian
Published: December 2009

This study analyzes the oceanic pathway connecting the Agulhas Bank to the southern Benguela upwelling system by means of a quantitative Lagrangian interpretation of the velocity field calculated by a high‐resolution numerical simulation of the ocean around the southwestern tip of Africa. The regional ocean model is forced with National Centers for Environmental Prediction surface winds over 1993–2006 and offers a relevant numerical platform for the investigation of the variability of the water transferred between both regions, both on seasonal and intraseasonal time scales. We show that the intensity of the connection fluctuates in response to seasonal wind variability in the west coast upwelling system, whereas intraseasonal anomalies are mostly related to the organization of the eddy field along the southwestern edge of the Agulhas Bank. Though the study only considers passive advection processes, it may provide useful clues about the strategy adopted by anchovies in their selection of successful spawning location and period. The pathway under investigation is of major interest for the ecology of the southern Benguela upwelling system because it connects the spawning grounds on the Agulhas Bank with the nursery grounds located on the productive upwelling off the west coast.
Phytoplankton blooms near the Pearl River Estuary induced by Typhoon Nuri
Authors: Zhao Hui , Tang DanLing , Wang Dongxiao
Published: December 2009

The authors investigate two phytoplankton blooms near or off the Pearl River Estuary (PRE) triggered by Category 2 Typhoon Nuri with moderate wind intensity in the South China Sea using both remotely sensed and in situ data sets. An offshore triangular phytoplankton bloom (chlorophyll a (Chl a) > 0.5 mg m−3) was observed near Dongsha Archipelago along Nuri's track, prolongating southeastward to 18°N 1 week after the typhoon's passage; a stronger nearshore phytoplankton increase (Chl a > 1.5 mg m−3) with high total suspended sediment appeared southwest of the PRE from the coast toward the South China Sea. After the typhoon's passage, sea surface cooling (∼3°C), strong wind (>20 m s−1), and heavy rainfall (>100 mm d−1) were also observed in the region, especially offshore. In addition, the freshwater discharge from the PRE during the typhoon passage increased fivefold in comparison with the August climatology in the nearshore bloom region. The nearshore bloom was probably due to the increased discharge from the PRE and favorable current, as well as mixing, upwelling, and near‐inertial resonance driven by strong typhoon wind. The offshore bloom may be triggered by upwelling and entrainment induced by strong typhoon wind and the topography of islands and islets. The present study suggests that one typhoon may nourish phytoplankton biomass by inducing transport of nutrient‐rich water from both the Pearl River Estuary to offshore and the sublayer to surface.
Oncogenic Product HMGA1a Might Function as an Aberrant Splicing Inducer of Estrogen Receptor [alpha] in Breast Cancer
Authors: Ohe Kenji , Utsumi Toshiaki , Mayeda Akila
Published: December 2009

Estrogen receptor (ER)-[alpha]46 is known as an important isoform for ER[alpha]. It inhibits the function of full length ER[alpha] in MCF-7 mammary carcinoma cells and associated with cell cycle arrest. On the other hand, the oncogene HMGA1 (formally HMG I/Y) is known to have increased expression in mammary carcinoma correlating with the degree of malignancy. We present here that HMGA1a (HMG I) induces the exon skipped product, ER[alpha]46 mRNA, by tethering U1 snRNP to an upstream pseudo 5' splice site, which is quite analogous to the PSI-mediated splicing regulation of Drosophila P-element.