bluuebunny/crossref_metadata_2025 huggingface dataset:
Mapping thin resistors and hydrocarbons with marine EM methods, Part II — Modeling and analysis in 3D
Authors: Weiss Chester J. , Constable Steven
Published: November 2006

The electromagnetic fields surrounding a thin, subseabed resistive disk in response to a deep-towed, time-harmonic electric dipole antenna are investigated using a newly developed 3D Cartesian, staggered-grid modeling algorithm. We demonstrate that finite-difference and finite-volume methods for solving the governing curl-curl equation yield identical, complex-symmetric coefficient matrices for the resulting [Formula: see text] linear system of equations. However, the finite-volume approach has an advantage in that it naturally admits quadrature integration methods for accurate representation of highly compact or exponentially varying source terms constituting the right side of the resulting linear system of equations. This linear system is solved using a coupled two-term recurrence, quasi-minimal residual algorithm that doesnot require explicit storage of the coefficient matrix, thus reducing storage costs from [Formula: see text] to [Formula: see text] complex, double-precision words with no decrease in computational performance. The disk model serves as a generalized representation of any number of resistive targets in the marine environment, including basaltic sills, carbonates, and stratigraphic hydrocarbon traps. We show that spatial variations in electromagnetic phase computed over the target are sensitive to the disk boundaries and depth, thus providing a useful complement to the usual amplitude-versus-offset analysis. Furthermore, we estimate through the calculation of Fréchet sensitivity kernels those regions of the 3D model which have the greatest effect on seafloor electric fields for a given source/receiver configuration. The results show that conductivity variations within the resistive disk have a stronger influence on the observed signal than do variations in the surrounding sediment conductivity at depth.
Validating airborne vector gravimetry data for resource exploration
Authors: Annecchione Maria A. , Keating Pierre , Chouteau Michel
Published: November 2006

Airborne gravimeters based on inertial navigation system (INS) technology are capable, in theory, of providing direct observations of the horizontal components of anomalous gravity. However, their accuracy and usefulness in geophysical or geological applications is unknown. Determining the accuracy of airborne horizontal component data is complicated by the lack of ground-surveyed control data. We determine the accuracy of airborne vector gravity data internally using repeatedly flown line data. Multilevel wavelet analyses of raw vector gravity data elucidate the limiting error source for the horizontal components. We demonstrate the usefulness of the airborne horizontal component data by performing Euler deconvolutions on real vector gravity data. The accuracy of the horizontal components is lower than the accuracy of the vertical component. Wavelet analyses of data from a test flight over Alexandria, Ontario, Canada, show that the main source of error limiting the accuracy of the horizontal components is time-dependent platform alignment errors. Euler deconvolutions performed on the Timmins data set show that the horizontal components help in constraining the 3D locations of regional geological features. It is thus concluded that the quality of the airborne horizontal component data is sufficient to motivate their use in resource exploration and geological applications.
On the application of Euler deconvolution to the analytic signal
Authors: Florio G. , Fedi M. , Pasteka R.
Published: November 2006

Standard Euler deconvolution is applied to potential-field functions that are homogeneous and harmonic. Homogeneity is necessary to satisfy the Euler deconvolution equation itself, whereas harmonicity is required to compute the vertical derivative from data collected on a horizontal plane, according to potential-field theory. The analytic signal modulus of a potential field is a homogeneous function but is not a harmonic function. Hence, the vertical derivative of the analytic signal is incorrect when computed by the usual techniques for harmonic functions and so also is the consequent Euler deconvolution. We show that the resulting errors primarily affect the structural index and that the estimated values are always notably lower than the correct ones. The consequences of this error in the structural index are equally important whether the structural index is given as input (as in standard Euler deconvolution) or represents an unknown to be solved for. The analysis of a case history confirms serious errors in the estimation of structural index if the vertical derivative of the analytic signal is computed as for harmonic functions. We suggest computing the first vertical derivative of the analytic signal modulus, taking into account its nonharmonicity, by using a simple finite-difference algorithm. When the vertical derivative of the analytic signal is computed by finite differences, the depth to source and the structural index consistent with known source parameters are, in fact, obtained.
Distinct Expression of Galectin‐3 in Pheochromocytomas
Authors: GIMM OLIVER , KRAUSE ULF , BRAUCKHOFF MICHAEL , HOANG‐VU CUONG , DRALLE HENNING
Published: November 2006

Abstract:  Unless distant metastases or local invasion are present, the diagnosis of malignant pheochromocytoma is challenging. Hence, biological markers are sought after and we thought to examine galectin‐3 in such a role. Four malignant and 24 benign (10 sporadic, 14 hereditary) pheochromocytomas were analyzed for the expression of galectin‐3. One malignant pheochromocytoma with distant metastases showed strong and one malignant undifferentiated pheochromocytoma with local invasion showed partly strong cytoplasmic staining. Nine of 10 sporadic and all hereditary benign pheochromocytomas had absent/weak staining. One benign sporadic pheochromocytoma had moderate cytoplasmic staining. The distinct expression in various types of pheochromocytomas is intriguing and requires further investigation.
Expression and Effect of Transforming Growth Factor‐α and Tumor Necrosis Factor‐α in Human Pheochromocytoma
Authors: TONG AN‐LI , ZENG ZHENG‐PEI , LI HAN‐ZHONG , YANG DI , LU LIN , LI MING
Published: November 2006

Abstract:  This study observed the expression of transforming growth factor‐α (TGF‐α) and tumor necrosis factor‐α (TNF‐α) in pheochromocytoma (PHEO) tissue and examined their effects on the proliferation and apoptosis of human PHEO cells. The mRNA and protein expressions of TGF‐α and TNF‐α were higher in PHEO tissues than in normal adrenal medullary tissues, and their expressions varied with pathological features. TGF‐α and TNF‐α stimulated the proliferation of primary human PHEO cells, but had no effect on the cell apoptosis. Both TGF‐α and TNF‐α might be involved in the pathogenesis of human PHEO. TNF‐α needs to be further investigated before its treatment of PHEO can be realized in clinical practice.
Multicenter Study on the Diagnostic Value of a New RIA for the Detection of Free Plasma Metanephrines in the Work‐Up for Pheochromocytoma
Authors: LENZ TOMAS , ZORNER JOACHIM , KIRCHMAIER CARL , PILLITTERI DANIELE , BADENHOOP KLAUS , BARTEL CHRISTINE , GEIGER HELMUT , HASSELBACHER KATRIN , TUSCHY ULRICH , WESTERMANN JÜRGEN , SALEWSKI LOTHAR
Published: November 2006

Abstract:  Available laboratory test methods for the detection of elevated concentrations of catecholamines and their metabolites in urine and/or plasma are not always sensitive enough for the detection of pheochromocytoma. High‐quality immunoassays for these compounds appear to be as accurate as high‐pressure liquid chromatography (HPLC) or gas chromatography/mass spectrometry (GC‐MS). Therefore, the current project aims to establish a new sensitive radioimmunoassay (RIA) for the measurement of free metanephrines in the plasma of patients in the work‐up for pheochromocytoma. We report first results of an ongoing multicenter clinico–chemical evaluation study in hypertensive patients and normotensive volunteers. After an overnight fast plasma samples were collected on ice in EDTA‐ and heparin‐coated tubes after insertion of an indwelling venous line and resting in the supine (patients) or sitting position (normal volunteers) for 30 min. Plasma metanephrines were measured by a newly developed RIA from IBL, Hamburg, Germany. Good agreement of the assay with the tandem mass spectrometry (LC‐MS/MS) method for normetanephrine (r2= 0.975) and for metanephrine (r2= 0.985) could be demonstrated. Both specimens, EDTA and heparin plasma, can be used with the same results. The RIA has a good precision of <15% in the normal range and of <10% in the elevated concentration range. Our preliminary data suggest a high validity of the newly developed RIA for measuring free metanephrine and normetanephrine in hypertensive subjects in both EDTA and heparin plasma. Further work is required to determine the accuracy of the test in larger patient populations and in patients with pheochromocytoma.
Risk‐Oriented Approach to Hereditary Adrenal Pheochromocytoma
Authors: MACHENS ANDREAS , BRAUCKHOFF MICHAEL , GIMM OLIVER , DRALLE HENNING
Published: November 2006

Abstract:  Hereditary adrenal pheochromocytoma is caused by germline mutations in RET, VHL, SDHB, SDHD, and NF1. As these genes differ in function, so may their pheochromocytoma phenotypes, suggesting gene‐specific patterns of age‐related progression to pheochromocytoma. This possibility was explored for gene carriers with a lifetime risk of pheochromocytoma in excess of 50%. Published age‐standardized penetrance rates of VHL‐, SDHB‐, and SDHD‐associated pheochromocytoma were gauged against age‐standardized penetrance rates of MEN2‐associated pheochromocytoma in 219 institutional carriers of RET mutations conferring highest (codon 918), high (codons 609, 611, 618, 620, 630, and 634) and least high risk (codons 768, 790, 791, 804, and 891). The highest‐risk category included SDHB, SDHD, and the highest‐risk RET genotype; the high‐risk category VHL missense mutations and the high‐risk RET genotypes; and the least‐high risk category VHL truncating mutations and least‐high risk RET genotypes. Detailed information on recurrence rates and intervals was available only for the RET carriers (19–31% and means of 4.3–5.5 years; all RET risk categories combined). Ipsilateral recurrences in adrenal remnants, and contralateral recurrences in virgin adrenals were comparable in incidence (27% and 39%, P= 0.69; high‐risk RET category) and time to recurrence (means of 4.3 vs. 5.4 year; P > 0.99; high‐risk RET category), discounting a major effect of tumor spillage at primary subtotal adrenalectomy on pheochromocytoma recurrence. The risk of malignancy usually is low, except for SDHB (38%). For most hereditary pheochromocytomas, endoscopic subtotal adrenalectomy is the procedure of choice. Grouping hereditary pheochromocytoma into preliminary risk categories may improve the management of gene carriers at risk of developing pheochromocytomas.
Mortality Associated with Pheochromocytoma
Authors: KHORRAM‐MANESH AMIR , JANSSON SVANTE , WÄNGBERG BO , NILSSON OLA , TISELL LARS‐ERIK , AHLMAN HÅKAN
Published: November 2006

Abstract:  A consecutive series of patients (68 females and 53 males) with pheochromocytoma (PC, n= 110) or paraganglioma (PG, n= 11) were treated at the Sahlgrenska University Hospital (1950–1997). During the observation period (15 ± 6 years) 42 patients died versus 23.6 expected in the general population (P < 0.001). There was no surgical mortality. Twenty patients died of cardiovascular disease, 11 of other tumors, and 7 of other diseases, but only 4 of PC/PG. The main causes of death in this regional series were cardiovascular diseases and tumor in a ratio of 1.3 versus 2.0 in the general Swedish population. Analysis of the mortality in all patients with clinically diagnosed PC (n= 481, 259 women and 222 men) based on the National Cancer Registry (1957–1997) showed that the number of deaths in this cohort was 196 versus 153.4 expected (P < 0.001). These patients had almost four times higher risk of dying of a tumor than did the general population (similar risk for females and males). There was no increased risk for cardiovascular death; in fact, the risk was lower than expected for men (22 vs. 38 expected). A second tumor diagnosed subsequent to PC occurred in 68 versus 31 expected. In men tumors of the liver and biliary tract and central nervous system and in women malignant melanoma and cervix carcinoma were most frequent. The results from the national series thus confirm an increased risk of a second tumor and increased tumor‐related mortality in patients with PC.
Malignant Pheochromocytoma
Authors: AHLMAN HÅKAN
Published: November 2006

Abstract:  The prevalence of malignant pheochromocytoma is about 10%, and is somewhat higher for paraganglioma. A problem for clinical follow‐up is that patients with “benign” histopathologic findings may develop metastatic disease. At the first international symposium on pheochromocytoma in Bethesda (2005) experts from different disciplines and patients shared their experiences, and the present knowledge of this rare disease was updated. The discussion related to future strategies for better clinical/histopathologic diagnosis and understanding of different geno‐ and phenotypes. Curative surgery can only seldom be performed because of multiple metastases. The main therapeutic goal is therefore often tumor reduction and control of hypertension. To date the best adjunct to surgery is radionuclide therapy using 131I‐MIBG, but the background information for optimal treatment is still incomplete. Certain patients may benefit from 131I‐MIBG combined with radiotherapy via somatostatin receptors expressed by the tumor, or the combination with chemotherapy. The need for future multicenter studies was emphasized. In experimental models the work on enhanced expression of amine transporters critical for radiotherapy is continued. Ongoing microarray studies will reveal novel intracellular pathways of importance for proliferation/cell cycle control, which can be inhibited by pharmacologic tools.
Development of Novel Tools for the Diagnosis and Prognosis of Pheochromocytoma Using Peptide Marker Immunoassay and Gene Expression Profiling Approaches
Authors: ANOUAR YOUSSEF , YON LAURENT , GUILLEMOT JOHANN , THOUENNON ERWAN , BARBIER LAURE , GIMENEZ‐ROQUEPLO ANNE‐PAULE , BERTHERAT JEROME , LEFEBVRE HERVE , KLEIN MARC , MURESAN MIHAELA , GROUZMANN ERIC , PLOUIN PIERRE‐FRANÇOIS , VAUDRY HUBERT , ELKAHLOUN ABDEL G.
Published: November 2006

Abstract:  Pheochromocytomas (PHEOs) are rare catecholamine‐producing neoplasias that arise from chromaffin cells of the adrenal medulla or from extra‐adrenal locations. These neuroendocrine tumors are usually benign, but may also present as or develop into a malignancy. There are currently no means to predict or to cure malignant tumors which have a poor prognosis. We have recently validated several assays for the measurement of peptides derived from chromogranin A (CgA) and secretogranin II (SgII) in order to determine whether these secreted neuroendocrine products could provide useful, complementary markers for the diagnosis and prognosis of PHEOs. Both the CgA‐derived peptide WE14 and the SgII‐derived peptide EM66 proved to be sensitive circulating markers for the diagnosis of PHEO. In addition, much higher EM66 levels were measured in benign than in malignant tumoral tissues, suggesting that this peptide could represent a valuable tool for the prognosis of PHEO. We have also initiated a comparative microarray study of benign and malignant PHEOs, which allowed the identification of a set of about 100 genes that were differentially expressed and best discriminated the two types of tumors. A large majority of these genes were expressed at lower levels in the malignant disease and were associated with various characteristics of chromaffin cells, such as hormone secretion signaling and machinery, peptide maturation, and cellular morphology. Altogether, these studies provide novel tools for the management of PHEO, and new insights for the understanding of tumorigenesis in chromaffin cells, which may offer potential therapeutic strategies.
Methamphetamine Induces Autophagy and Apoptosis in a Mesencephalic Dopaminergic Neuronal Culture Model
Authors: KANTHASAMY ARTHI , ANANTHARAM V. , ALI SYED F. , KANTHASAMY A.G.
Published: November 2006

Abstract:  Autophagy is a phylogenetically conserved process that plays a critical role in the degradation of oxidatively damaged proteins and organelle turnover. The role of oxidative stress and apoptosis in methamphetamine (METH)‐induced neurotoxicity is well known; however, the potential contribution of autophagy to METH‐induced oxidative damage in dopaminergic neuronal systems remains unclear. The goals of the present article were twofold: (a) to develop an in vitro dopaminergic cell culture model to study cellular and molecular mechanisms underlying METH‐ind‐uced autophagy and apoptosis, and (b) to determine whether lysosomal protease cathepsin‐D activation, resulting from the loss of lysosomal membrane integrity, contributes to METH‐induced apoptosis. To accomplish these goals, we characterized morphological and biochemical changes in an immortalized mesencephalic dopaminergic neuronal cell line (N27 cells) following treatment with METH. Exposure of METH (2 mM) to N27 cells resulted in the appearance of cytoplasmic vacuolar structures reminiscent of autophagic vacuoles within 3 h. In order to ascertain the identity of the vacuolar structures that are formed following METH exposure, immunohistochemical staining for markers of autophagy were performed. LAMP 2, a classical marker of autophagolysosomes, revealed an extensive punctuate pattern of distribution on the vacuolar membrane surface, with exclusive localization in the cytoplasm. Additionally, using DNA fragmentation analysis we showed a dose‐dependent increase in fragmented DNA in METH treated N27 cells. Since METH‐induced autophagy preceded DNA fragmentation, we tested whether dysfunction of the autophagolysosomal system contributes to nuclear damage. Immunofluorescence studies with cathepsin‐d demonstrated a granular pattern of staining in untreated cells, whereas an increased cathepsin‐ D immunoreactivity with a globular pattern of staining was observed in METH‐treated cells. Nevertheless, blockade of cathepsin‐D activation by pepstatin‐A, cathepsin‐D inhibitor, failed to alter METH‐induced DNA fragmentation. Collectively, these results demonstrate that N27 dopaminergic neuronal cell model may serve as an excellent in vitro model to study the mechanisms of METH‐induced autophagy and apoptosis. Furthermore, it is less likely that cathepsin‐D may serve as a trigger for the induction of apoptosis subsequent to exposure of N27 dopaminergic neuronal cells to METH.
Learning Phonology With Substantive Bias: An Experimental and Computational Study of Velar Palatalization
Authors: Wilson Colin
Published: November 2006

There is an active debate within the field of phonology concerning the cognitive status of substantive phonetic factors such as ease of articulation and perceptual distinctiveness. A new framework is proposed in which substance acts as a bias, or prior, on phonological learning. Two experiments tested this framework with a method in which participants are first provided highly impoverished evidence of a new phonological pattern, and then tested on how they extend this pattern to novel contexts and novel sounds. Participants were found to generalize velar palatalization (e.g., the change from [k] as in keep to [t⌢∫S] as in cheap) in a way that accords with linguistic typology, and that is predicted by a cognitive bias in favor of changes that relate perceptually similar sounds. Velar palatalization was extended from the mid front vowel context (i.e., before [e] as in cape) to the high front vowel context (i.e., before [i] as in keep), but not vice versa. The key explanatory notion of perceptual similarity is quantified with a psychological model of categorization, and the substantively biased framework is formalized as a conditional random field. Implications of these results for the debate on substance, theories of phonological generalization, and the formalization of similarity are discussed.
Protective role of γ-aminobutyric acid against chronic renal failure in rats
Authors: Sasaki Sumiyo , Yokozawa Takako , Cho Eun Ju , Oowada Shigeru , Kim Mujo
Published: November 2006

The protective effect of γ-aminobutyric acid (GABA) against chronic renal failure (CRF) was investigated using a remnant kidney model with 5/6 nephrectomized rats. Nephrectomy led to renal dysfunction, which was evaluated via several parameters including serum urea nitrogen, creatinine (Cr) and Cr clearance. However, the administration of GABA ameliorated renal dysfunction, and a longer administration period of GABA increased its protective effect. In addition, nephrectomized control rats showed an elevation in the fractional excretion of sodium (FENa) with an increase in urinary sodium, while GABA led to a significant decline in FENa. Moreover, nephrectomy resulted in a decrease of serum albumin and an increase of urinary protein with a change in the urinary protein pattern, whereas the rats administered GABA showed improvement in these changes associated with CRF caused by nephrectomy. This suggests that GABA would inhibit the disease progression and have a protective role against CRF. As one of the risk factors for CRF progression, hypertension was also regulated by GABA. The results also indicate that GABA may play a protective role against CRF through improvement of the serum lipid profile, with reductions in triglyceride and total cholesterol. Furthermore, nephrectomy led to renal oxidative stress with a decrease in the activity of antioxidative enzymes and elevation of lipid peroxidation. The administration of GABA attenuated oxidative stress induced by nephrectomy through an increase in superoxide dismutase and catalase, and decrease in lipid peroxidation. The histopathological lesions, including glomerular, tubular and interstitial lesions, under nephrectomy were also improved by GABA with the inhibition of fibronectin expression. This study demonstrated that GABA attenuated renal dysfunction via regulation of blood pressure and lipid profile, and it also ameliorated the oxidative stress induced by nephrectomy, suggesting the promising potential of GABA in protecting against renal failure progression.
How i do it head and neck and plastic surgery a targeted problem and its solution: Endoscopic septoplasty
Authors: Giles William C. , Gross Charles W. , Abram Adam C. , Greene W. Michael , Avner Ted G.
Published: November 2006

Often there is a need to address the status of the nasal septum during functional endonasal sinus surgery. The outcome of a sinus procedure can be enhanced if the surgeon has better exposure of the operative area or if the patient receives a larger nasal airway, which provides laminar air flow. We present a technique of managing septal deviations and obstructions that adds little additional time to the sinus procedure and allows direct evaluation of the septum with the endoscopes. We describe this relatively simple technique, indications for its use, and results of the first 38 cases.
Bridging research and policy: insights from 50 case studies
Authors: Court Julius , Young John
Published: November 2006

English

While we know of a lot about research–policy links in rich countries, there has been very little systematic work on those in the rest of the world. This article reports on the process, findings and implications of an initiative to collect and analyse 50 summary case studies on research–policy links from developing and transition countries. The discussion is structured around a framework of three interlinked domains: context, evidence, links. The article also refers to other issues that emerge from the case studies, particularly the role of external influences and donors. Finally, it emphasises the impor tance of translating the findings into practical recommendations for policy makers, donors and researchers.
Die Genitivflexion von artikellos verwendbaren Eigennamen als syntaktisch konditionierte Allomorphie
Authors: Neef Martin
Published: November 2006

Based on Eisenberg's (2000) insight that German has four genders instead of three, genitive singular inflection turns out to be driven by gender alone. The concept of inflection classes can be dispensed with for this subject. However, as has been noticed, proper names disturb this clear picture because a subset of female proper names seems to vacillate between zero inflection as is typical of female nouns and s-inflection as is typical of masculine and neuter nouns. On closer inspection, it turns out that the s-marker for female proper names differs significantly from the s-marker for masculine and neuter generic nouns. Moreover, non-female proper names may also show zero inflection in the genitive. In order to analyze these data, I distinguish two distinct classes of proper names: members of the first class of proper names are allowed to appear without an article in contexts where members of the other class need one. I call this first class ‘grammatical proper names’. In genitive singular inflection, grammatical proper names are either zero marked or marked by a specific s-marker. The conditioning factor is whether or not the head position of the DP is filled with a word.
15N-labed glycine synthesis
Authors: Tavares Claudinéia R.O. , Bendassolli José A. , Coelho Fernando , Sant'ana Filho Carlos R. , Prestes Clelber V.
Published: November 2006

This work describes a method for 15N-isotope-labeled glycine synthesis, as well as details about a recovery line for nitrogen residues. To that effect, amination of alpha-haloacids was performed, using carboxylic chloroacetic acid and labeled aqueous ammonia (15NH3). Special care was taken to avoid possible 15NH3 losses, since its production cost is high. In that respect, although the purchase cost of the 13N-labeled compound (radioactive) is lower, the stable tracer produced constitutes an important tool for N cycling studies in living organisms, also minimizing labor and environmental hazards, as well as time limitation problems in field studies. The tests were carried out with three replications, and variable 15NH3(aq) volumes in the reaction were used (50, 100, and 150 mL), in order to calibrate the best operational condition; glycine masses obtained were 1.7, 2, and 3.2 g, respectively. With the development of a system for 15NH3 recovery, it was possible to recover 71, 83, and 87% of the ammonia initially used in the synthesis. With the required adaptations, the same system was used to recover methanol, and 75% of the methanol initially used in the amino acid purification process were recovered.
Mitochondrial DNA damage associated with lipid peroxidation of the mitochondrial membrane induced by Fe2+-citrate
Authors: Almeida Andréa M. , Bertoncini Clélia R.A. , Borecký Jiri , Souza-Pinto Nadja C. , Vercesi Aníbal E.
Published: November 2006

Iron imbalance/accumulation has been implicated in oxidative injury associated with many degenerative diseases such as hereditary hemochromatosis, beta-thalassemia, and Friedreich's ataxia. Mitochondria are particularly sensitive to iron-induced oxidative stress - high loads of iron cause extensive lipid peroxidation and membrane permeabilization in isolated mitochondria. Here we detected and characterized mitochondrial DNA damage in isolated rat liver mitochondria exposed to a Fe2+-citrate complex, a small molecular weight complex. Intense DNA fragmentation was induced after the incubation of mitochondria with the iron complex. The detection of 3' phosphoglycolate ends at the mtDNA strand breaks by a 32P-postlabeling assay, suggested the involvement of hydroxyl radical in the DNA fragmentation induced by Fe2+-citrate. Increased levels of 8-oxo-7,8-dihydro-2'-deoxyguanosine also suggested that Fe2+-citrate-induced oxidative stress causes mitochondrial DNA damage. In conclusion, our results show that iron-mediated lipid peroxidation was associated with intense mtDNA damage derived from the direct attack of reactive oxygen species.
A link between the hippocampal and the striatal memory systems of the brain
Authors: Rossato Janine I. , Zinn Carolina G. , Furini Cristiane , Bevilaqua Lia R.M. , Medina Jorge H. , Cammarota Martín , Izquierdo Iván
Published: November 2006

Two major memory systems have been recognized over the years (Squire 1987): the declarative memory system, which is under the control of the hippocampus and related temporal lobe structures, and the procedural or habit memory system, which is under the control of the striatum and its connections. Most if not all learning tasks studied in animals, however, involve either the performance or the suppression of movement; this, if learned well, may be viewed as having become a habit. It is agreed that memory rules change from their first association to those that take place when the task is mastered. Does this change of rules involve a switch from one memory system to another? Here we will comment on: 1) reversal learning in the Morris water maze (MWM), in which the declarative or spatial component of a task is changed but the procedural component (to swim to safety) persists and needs to be re-linked with a different set of spatial cues; and 2) a series of observations on an inhibitory avoidance task that indicate that the brain systems involved change with further learning.
Pancreatite aguda experimental induzida pela L-arginina: avaliação histológica e bioquímica
Authors: Ramos Jr. Odery , Leitão Olival Ronald , Repka João Carlos Domingues , Barros Sérgio Gabriel da Silva
Published: November 2006

RACIONAL: Doses excessivas de aminoácidos básicos como a L-arginina têm a capacidade de lesar o pâncreas de ratos. OBJETIVO: Descrever e avaliar as características bioquímicas e histológicas da pancreatite aguda induzida pela L-arginina em ratos durante a instalação, desenvolvimento e reparação do processo inflamatório pancreático. MATERIAL E MÉTODOS: A amostra constituiu-se de 105 ratos machos, da linhagem Wistar. Aos ratos do grupo experimento (n = 70) administrou-se injeção intraperitonial de 500 mg/100 g de peso corporal de L-arginina. No grupo controle (n = 35) foi injetada solução salina isotônica. Analisaram-se 10 animais do grupo experimento e 5 do grupo controle em cada período de 6 h, 12 h, 24 h, 48 h, 72 h, 7 dias e 14 dias. Durante os tempos determinados coletou-se sangue para exames laboratoriais e o pâncreas para análise em microscopia óptica. RESULTADOS: Doze a 24 horas após a injeção de L-arginina os níveis séricos de amilase atingiram valores máximos, comparados àqueles dos ratos controle, decrescendo gradualmente, alcançou-os na 48ªhora sendo significativamente menor após 72 horas e 7 dias. A atividade enzimática retornou a níveis basais após 14 dias. Os valores de amilase estavam normais em todos os tempos avaliados nos animais do grupo controle. Na microscopia óptica, após injeção de L-arginina, observou-se arquitetura pancreática histologicamente preservada no período de 6 horas, evidenciando-se em 24 horas importante edema intersticial. Após 48 horas, a arquitetura acinar estava parcialmente destruída com necrose celular focal, atingindo sua máxima severidade ao ultrapassar 72 horas. No 7º dia a necrose tecidual e o edema haviam diminuído, iniciando-se a regeneração da arquitetura acinar. Observou-se a reconstrução estrutural pancreática após 14 dias. No grupo controle não se encontraram alterações histológicas pancreáticas. CONCLUSÃO: A pancreatite aguda experimental induzida pela L-arginina induz a necrose pancreática, apresentando evolução auto-limitada com regeneração do pâncreas em 2 semanas.
Enxertos vasculares homólogos e heterólogos conservados em glicerina na fleboplastia da jugular em eqüinos
Authors: Stainki D.R. , Alves G.E.S. , Vasconcelos A.C. , Barbosa M.P. , Oliveira H.P.
Published: November 2006

Doze eqüinos foram divididos aleatoriamente em dois grupos de seis animais (grupos I e II), com a finalidade de estudar a compatibilidade tecidual e a propriedade de indução de trombos de dois tecidos biológicos conservados em glicerina a 98%. Esses tecidos foram usados na restauração da jugular externa e se constituíram de artéria carótida comum homóloga (ACCHo), no grupo I, e veia jugular externa heteróloga (VJEHe), no grupo II. Para a restauração, utilizaram-se duas técnicas de anastomose da jugular, sendo, no grupo I, a técnica de bypass e, no grupo II, a substituição de um segmento da jugular esquerda por meio de anastomose vascular término-terminal. Para avaliar a trombogênese local e a histocompatibilidade, foram realizados exames clínicos, hematológicos, ecoDopplercardiográficos e histológicos dos segmentos vasculares enxertados. Os segmentos foram colhidos após 45 dias da avaliação pós-operatória, tendo a jugular direita como testemunha para os exames histológicos. Ambos os tecidos foram compatíveis quando implantados nos eqüinos, sem processo inflamatório acentuado, indicativo de rejeição. A técnica de bypass não foi eficiente na restauração da jugular, ocorrendo trombose obliterante dos enxertos de ACCHo. A substituição completa do segmento da jugular por VJEHe pode ser viável para o restabelecimento do fluxo sangüíneo da jugular de eqüinos, desde que se mantenha a igualdade dos diâmetros entre o enxerto e o vaso receptor.
Resposta da paratireóide de ratas às variações do cálcio e fósforo plasmáticos no hipertireoidismo e hipogonadismo
Authors: Serakides R. , Ocarino N.M. , Cardoso T.G.S. , Moraes J.R.C. , Nunes V.A. , Silva A.E.
Published: November 2006

Foram estudadas 84 paratireóides de ratas Wistar com cinco meses de idade, castradas ou não, e mantidas em hipertireoidismo por períodos de 30, 60 e 90 dias. Dois grupos eutireóideos, um castrado e o outro não, foram mantidos nas mesmas condições e serviram de controle. Ao final de cada período, foram colhidos o plasma, para determinação da concentração de T4 livre, o cálcio e o fósforo e as paratireóides, para análise morfológica e determinação da porcentagem de núcleo, citoplasma e estroma. Aos 90 dias houve reversão da hipocalcemia observada aos 60 dias nos animais eutireóideos castrados e não castrados, graças à hipertrofia da paratireóide. O mesmo não ocorreu com os grupos hipertireóideos que apresentaram hipocalcemia e hiperfosfatemia progressivas e não compensadas até os 90 dias. Na castração há pronta reversão da hipocalcemia em resposta ao aumento da atividade funcional da paratireóide. No estado hipertireóideo com gônadas funcionais, apesar da hipertrofia da paratireóide, não há retorno à isocalcemia e isofosfatemia. Na associação hipertireoidismo-castração, a paratireóide não responde satisfatoriamente à hipocalcemia e hiperfosfatemia intensas e progressivas.
Caracterização morfológica das fases imaturas e tempo de desenvolvimento de Muscidifurax uniraptor Kogan & Legner (Hymenoptera: Pteromalidae)
Authors: Thomazini Marcílio J. , Lino Neto José , Costa Valmir A. , Berti Filho Evoneo
Published: November 2006

As fases imaturas do parasitóide Muscidifurax uniraptor Kogan & Legner foram caracterizadas morfologicamente. Pupários de mosca-doméstica com 48-72h de idade foram expostos aos parasitóides adultos em laboratório (25±1ºC, 70±10% U.R. e 14h de fotofase) por um período de 18h. Diariamente, amostras dos pupários foram dissecadas para observação dos imaturos. Em microscópio eletrônico de varredura foram efetuadas medidas de cápsula cefálica das larvas e eletromicrografias dos imaturos. Foi possível determinar quatro ínstares larvais para M. uniraptor. As larvas dos diferentes ínstares são semelhantes na forma geral e nos movimentos, diferindo no tamanho e no volume, apresentando perda gradual de transparência de um ínstar para outro. Houve sobreposição de fases durante o desenvolvimento de ovo a adulto do parasitóide.
Interação tritrófica entre Podisus nigrispinus (Dallas) (Heteroptera: Pentatomidae), Eucalyptus e lagartas de Thyrinteina arnobia (Stoll) (Lepidoptera: Geometridae): I visitação
Authors: Cavalcanti Maria das G , Vilela Evaldo F. , Eiras Álvaro E. , Zanuncio José C. , Picanço Marcelo C.
Published: November 2006

Estudou-se a interação tritrófica envolvendo o predador Podisus nigrispinus (Dallas) e cinco espécies de Eucalyptus injuriadas por lagartas de Thyrinteina arnobia (Stoll). P. nigrispinus visitou mais plantas de E. pellita do que de outras espécies e a área da superfície foliar mostrou ser o fator primário (r = 0,88) envolvido na interação. A presença do herbívoro na planta induziu o maior número de visitas do predador, sugerindo uma interação entre a planta hospedeira e o herbívoro, provavelmente mediada por cairomônios.
On the kinematics of 2D tunnel collapse in undrained clay
Authors: Osman A. S. , Mair R. J. , Bolton M. D.
Published: November 2006

A kinematic plastic solution has been developed for ground movements around a shallow, unlined tunnel embedded within an undrained clay layer. In this solution, the pattern of deformation around the tunnel is idealised by a simple plastic deformation mechanism. Within the boundaries of the deformation mechanism, the soil is required to shear compatibly and continuously with no relative sliding at the boundaries. The soil is regarded here as a rigid plastic (Tresca) material. The plausibility of the proposed mechanism is demonstrated by comparison with limit analysis calculations and centrifuge test results.
A comparison of field and laboratory tests of caisson foundations in sand and clay
Authors: Kelly R. B. , Houlsby G. T. , Byrne B. W.
Published: November 2006

Laboratory tests applying vertical and moment loads to suction caissons founded in sand and clay have been conducted to simulate an equivalent series of field tests. The caissons used in the laboratory were 0·15 m, 0·2 m and 0·3 m in diameter, whereas those for the field tests were 1·5 m and 3·0 m in diameter. The loads applied to the caissons in the laboratory tests were scaled from those in the field tests, and the models were loaded in a near-identical manner to the field trials. The test results are presented in non-dimensional form for comparison. The non-dimensional laboratory data from moment loading tests were similar to the field data in most cases. However, the non-dimensional data from vertically loaded caisson tests in the laboratory and in the field show more significant differences, and possible reasons for these are discussed.
Development of a real-time, near-optimal control process for water-distribution networks
Authors: Rao Zhengfu , Salomons Elad
Published: November 2006

This paper presents a new approach for the real-time, near-optimal control of water-distribution networks, which forms an integral part of the POWADIMA research project. The process is based on the combined use of an artificial neural network for predicting the consequences of different control settings and a genetic algorithm for selecting the best combination. By this means, it is possible to find the optimal, or at least near-optimal, pump and valve settings for the present time-step as well as those up to a selected operating horizon, taking account of the short-term demand fluctuations, the electricity tariff structure and operational constraints such as minimum delivery pressures, etc. Thereafter, the near-optimal control settings for the present time-step are implemented. Having grounded any discrepancies between the previously predicted and measured storage levels at the next update of the monitoring facilities, the whole process is repeated on a rolling basis and a new operating strategy is computed. Contingency measures for dealing with pump failures, pipe bursts, etc., have also been included. The novelty of this approach is illustrated by the application to a small, hypothetical network. Its relevance to real networks is discussed in the subsequent papers on case studies.
Urban stormwater toxic pollutants: assessment, sources, and treatability
Authors: Pitt Robert , Field Richard , Lalor Melinda , Brown Michael
Published: November 2006

This paper summarizes an investigation to characterize and treat selected storm water contaminants that are listed as toxic pollutants (termed toxicants in this paper) in the Clean Water Act, Section 307 (Arbuckle et al., 1991). The first project phase investigated typical toxicant concentrations in storm water, the origins of these toxicants, and storm and land‐use factors that influenced these toxicant concentrations. Of the 87 storm water source area samples analyzed, 9% were considered extremely toxic (using the Microtox® toxicity‐screening procedure). Moderate toxicity was exhibited in 32% of the samples, whereas 59% of the samples had no evidence of toxicity. Only a small fraction of the organic toxicants analyzed were frequently detected, with 1,3‐dichlorobenzene and fluoranthene the most commonly detected organics investigated (present in 23% of the samples). Vehicle service and parking area runoff samples had many of the highest observed concentrations of organic toxicants. All metallic toxicants analyzed were commonly found in all samples analyzed. The second project phase investigated the control of storm water toxicants using a variety of bench‐scale conventional treatment processes. Toxicity changes were monitored using the Microtox® bioassay test. The most beneficial treatment tests included settling for at least 24 hours (up to 90% reductions), screening and filtering through at least 40‐μm screens (up to 70% reductions), and aeration and/or photodegradation for at least 24 hours (up to 80% reductions). Because many samples exhibited uneven toxicity reductions for the different treatment tests, a treatment train approach was selected for the current project phase. This current phase includes testing of a prototype treatment device that would be useful for controlling runoff from critical source areas (e.g., automobile service facilities).
Role of adsorption in granular activated carbon‐fluidized bed reactors
Authors: Shi Jing , Zhao Xianda , Hickey Robert F. , Voice Thomas C.
Published: November 2006

A granular activated carbon‐fluidized bed reactor (GAC‐FBR) was used to treat groundwater contaminated with toluene. The performance of the reactor and the amount of adsorbed toluene on the GAC were investigated during start‐up, under pseudo‐steady‐state conditions, during a step‐increase in the applied organic loading rate (OLR) and after the OLR was returned to the initial level. Under constant, organic loading rate conditions (5.4 kg chemical oxygen demand/m3 day), 99.4% removal of an inlet toluene concentration of 2.7 mg/L was observed. The amount of adsorbed toluene was measured at various points in time by performing a solvent extraction on samples of GAC carrier removed from the FBR system. There were significant changes in the amount of toluene adsorbed onto the GAC during non‐steady state (start‐up and step OLR periods). This confirms the interpretation from previous biological activated carbon (BAC) studies that adsorption serves to dampen concentration changes in the system, thereby providing improved stability effluent quality and overall system efficiency compared with systems employing only biodegradation. The results also conclusively demonstrate that bioregeneration occurs in BAC systems such as the GAC‐FBR process configuration.
Measurement of bound water in sludges: A comparative study
Authors: Lee D. J. , Hsu Y. H.
Published: November 2006

The centrifugal settling, expression, differential scanning calorimetry (OSC), and drying tests are employed for measuring the bound water content in a sludge made of CaCO3, PYC, or glass powders, an inorganic Cu(OH)2 sludge, and an activated sludge. The bound water is found to be an operationally defined value that differs greatly when different measurement technique is applied. A classification scheme for dividing the moisture content in a sludge based on the bound water data is proposed.
Oxidation of simazine: Ozone, ultraviolet, and combined ozone/ultraviolet oxidation
Authors: Lai Ming‐Shen , Jensen J. N. , Weber A. S.
Published: November 2006

A laboratory study was conducted to investigate the kinetics and byproducts of simazine oxidation by ozone, ultraviolet radiation (UV), and combined ozone and UV. Byproducts were identified by HPLC. Simazine was oxidized rapidly by ozone, UV, and ozone and UV. For example, 4 mg/L simazine disappeared completely after oxidation by 34 mg/min ozone at pH 7.2 for 15 minutes. Simazine disappearance rates during ozonation increased with applied ozone dose and pH. Dealkylation and dechlorination byproducts were formed, and deamination byproducts appeared at higher ozone doses or higher pH. During UV and ozone and UV oxidation, simazine disappearance rates increased with UV intensity. Dechlorination byproducts were formed by UV oxidation. Dealkylation, deamination, and dechlorination byproducts were formed by combined ozone and UV treatment. In comparing oxidation systems, simazine disappearance rates during ozonation at pH 9.9 were similar to those observed during ozone and UV oxidation.
Regeneration of spent adsorbents using homogeneous advanced oxidation
Authors: Mourand John T. , Crittenden John C. , Hand David W. , Perram David L. , Notthakun Sawang
Published: November 2006

The removal of organic contaminants from water by adsorption processes results in spent adsorbents, and, in this research, the use of homogeneous advanced oxidation processes for destructive regeneration of adsorbents is investigated. These two homogeneous advanced oxidation processes are examined: hydrogen peroxide/ozone and ultraviolet light/hydrogen peroxide. The impacts of adsorbent, adsorbate, and temperature on regeneration were examined. The process was evaluated by the destruction efficiency, rate of regeneration, and the quantity of oxidants consumed. This study demonstrates that the regeneration of adsorbents by homogeneous advanced oxidation is not practical. This paper does not suggest other advanced oxidation processes that employ Fentons reagant or heterogeneous reactions using photoreactive metal catalysts (that is, TiO2) are ineffective for regeneration of adsorbents. The regeneration rate was found to be much faster for smaller particle size adsorbents and weakly adsorbed compounds; in some cases, nearly 100% of the virgin capacity was recovered after regeneration. However, in all cases, the regeneration process consumes more oxidants than would be required by simply using a conventional advanced oxidation process for destroying organic contaminants. The high consumption of oxidants may be due to the slow rate of organic desorption and redox reactions with the adsorbent surface. Accordingly, regeneration processes using homogeneous advanced oxidation is not practical unless an adsorbent is developed that exhibits fast desorption kinetics and the surface does not react with the oxidants.
A simple empirical model for hindered settling in activated sludge clarifier
Authors: Roche N. , Vaxelaire J. , Prost C.
Published: November 2006

The determination of activated sludge concentration at the bottom of secondary settler tanks is necessary for proper design and control of wastewater treatment plants. To model its time dependence and the effect of plant operation parameters, sludge thickening should be taken into account. Most of the models proposed in litterature require large computational efforts or the knowledge of parameters that require delicate measurements. This study gives a new equation for activated sludge thickening, Xi = a * (ti + Δt)b, determined from 23 different experiments, with formulas to obtain all the model parameters (a, b, and Δt). They have been fitted using settling data obtained on biomass sampled on different activated sludge treatment plants (industrial [brewery], municipal, and laboratory pilot plant). Model predictions are compared to experimental data obtained on a full‐scale secondary clarifier under unsteady‐state conditions.