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Environment Similar (environment + similar)
Selected AbstractsORIGINAL AND SECONDARY HIGH-FREQUENCY SANDSTORM ZONES IN THE LOESS PLATEAU REGION, CHINAGEOGRAFISKA ANNALER SERIES A: PHYSICAL GEOGRAPHY, Issue 2 2007JIONGXIN XU ABSTRACT. A study of sandstorms in the Loess Plateau and neighbouring areas is based on observations of sandstorms and precipitation. Through analysis of the relationship between the mean annual number of sandstorms and the mean annual precipitation, an original sandstorm zone and a secondary high-frequency zone of sandstorms have been defined. The latter is mainly formed as a result of human activities, such as vegetation destruction and waste-land cultivation, and not because of climatic change. The secondary sandstorm zone is located 350,500 km away from the original sandstorm zone, reflecting the fact that the sandstorm zone in the Loess Plateau area has shifted 350,500 km to the southeast, in response to human impact. Some abrupt change has been found in the area where the mean annual precipitation is 270 mm, where the original sandstorm zone ends and a secondary zone of high-frequency sandstorms begins. This transition area can be regarded as an abnormally unstable area. This study shows that destruction of the vegetation can cause changes in the environment similar to those attributed to climatic change. [source] The biogeography of prediction error: why does the introduced range of the fire ant over-predict its native range?GLOBAL ECOLOGY, Issue 1 2007Matthew C. Fitzpatrick ABSTRACT Aim, The use of species distribution models (SDMs) to predict biological invasions is a rapidly developing area of ecology. However, most studies investigating SDMs typically ignore prediction errors and instead focus on regions where native distributions correctly predict invaded ranges. We investigated the ecological significance of prediction errors using reciprocal comparisons between the predicted invaded and native range of the red imported fire ant (Solenopsis invicta) (hereafter called the fire ant). We questioned whether fire ants occupy similar environments in their native and introduced range, how the environments that fire ants occupy in their introduced range changed through time relative to their native range, and where fire ant propagules are likely to have originated. Location, We developed models for South America and the conterminous United States (US) of America. Methods, We developed models using the Genetic Algorithm for Rule-set Prediction (GARP) and 12 environmental layers. Occurrence data from the native range in South America were used to predict the introduced range in the US and vice versa. Further, time-series data recording the invasion of fire ants in the US were used to predict the native range. Results, Native range occurrences under-predicted the invasive potential of fire ants, whereas occurrence data from the US over-predicted the southern boundary of the native range. Secondly, introduced fire ants initially established in environments similar to those in their native range, but subsequently invaded harsher environments. Time-series data suggest that fire ant propagules originated near the southern limit of their native range. Conclusions, Our findings suggest that fire ants from a peripheral native population established in an environment similar to their native environment, and then ultimately expanded into environments in which they are not found in their native range. We argue that reciprocal comparisons between predicted native and invaded ranges will facilitate a better understanding of the biogeography of invasive and native species and of the role of SDMs in predicting future distributions. [source] Handling of biliary complications following laparoscopic cholecystectomy in the setting of Tripoli Central HospitalHPB, Issue 3 2002A Elhamel Background Laparoscopic cholecystectomy (LC) has an increased incidence of bile duct injury and bile leak when compared with open cholecystectomy. This study reviews management of these complications in a general hospital setting. Data collected from patients diagnosed and treated in one surgical unit for biliary complications after LC between 1992 and 1996 were analysed. Method A total of 14 patients were examined. Diagnosis was defined mainly by Endoscopic retrograde cholangiopancreatography (ERCP) and undetected choledocholitiasis was discovered in association with two of these complications. 43% of patients presented after LC with early postoperative bile leak or jaundice due to partial or complete bile duct excision or slippage of clips from the cystic duct. 57% presented with late biliary strictures. Thirteen patients were treated surgically, with biliary reconstruction (11 patients), direct repair (one) and cystic duct ligation in combination with clearance of bile duct from large multiple stones (one). One patient, who had clip displacement from cystic duct in combination with misplaced clip on right hepatic duct, was treated elsewhere. Postoperatively, one patient developed anastomotic leak and another died from sequellaie of bile duct transection requiring staged operations. Conclusions It is concluded that, in an environment similar to that where the authors had to work, LC should be performed in hospitals with facility to perform ERCP or when access for this technique is available in a nearby institution. Early recognition and immediate management of biliary injuries is dependent on individual resources and circumstances but, if required, consultation with colleagues or referral of patients with suspected or established biliary complications should not be delayed. [source] Long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency with inadvertent caries in infantsINTERNATIONAL JOURNAL OF PAEDIATRIC DENTISTRY, Issue 1 2007FELIX BLAKE Background., Long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (LCHADD) is a rare systemic disease that is associated with early tooth decay. Case report., This report describes the case of a 3-year-old boy suffering from LCHADD. At the time of referral, extensive carious lesions of the subject's maxillary dentition necessitated the surgical removal of eight teeth. Preventive treatment for LCHADD involves a regular oral intake of glucose that is vital for the survival of the affected individual. In young infants, the glucose solution needs to be administered as often as every 3 h in order to prevent hypoglycaemia, leading to a local environment similar to that experienced in nursing bottle syndrome. While nursing bottle syndrome can be resolved by eliminating the sugar substrate and curtailing the feeding sessions, these alternatives are not available in cases of LCHADD. Conclusion., This report highlights this rare disease and emphasizes its dire consequences for the dentition. Prophylactic recommendations for high-risk children are reviewed. Familiarity with LCHADD allows this high-risk group of patients to be identified, and thus, ensures diligent prophylactic action. [source] Rodents as Taphonomic Agents: Bone Gnawing by Brown Rats and Gray Squirrels,JOURNAL OF FORENSIC SCIENCES, Issue 4 2007Walter E. Klippel Ph.D. Abstract:, Passive infrared technology was used to film diurnal and nocturnal scavenging behavior of brown rats and gray squirrels at the University of Tennessee's Anthropological Research Facility. This direct documentation demonstrated that brown rats modified fat-laden cancellous bone while gray squirrels generally gnawed the thicker bone cortices only after fats had leached away. A case study placed in a shaded portion of the Facility indicated the postmortem interval for initial gnawing by gray squirrels was slightly over 30 months. An examination of 53 human skeletons in the William M. Bass Forensic Skeletal Collection revealed that 10 cases had gnaw marks consistent with those made by gray squirrels. One of the 10 cases had been gnawed within 16 months of time-since-death, while the remaining nine had postmortem intervals >30 months. Additional observed modifications made to nonhuman bone by gray squirrels indicate that squirrel gnaw marks on bone can serve as a minimal estimate of time-since-death in a temperate environment similar to that of East Tennessee. [source] Synthesis and Characterization of Degradable p(HEMA) Microgels: Use of Acid-Labile CrosslinkersMACROMOLECULAR BIOSCIENCE, Issue 4 2007Volga Bulmus Abstract New divinyl-functionalized acetal-based crosslinkers were synthesized as building elements to form acid-labile microgel particles for controlled-release applications. The synthesized crosslinkers underwent hydrolysis at slightly acidic pHs in less than 1 h while they were stable at neutral pHs for longer times. HEMA was copolymerized with the crosslinkers via an inverse emulsion polymerization technique using a redox initiator system at room temperature to form crosslinked, colloidal p(HEMA) microgels. Microgels in diameters ranging from 150 to 475 nm with narrow distribution could be produced. The crosslinking density and the diameter of the microgels were found to be controlled by monomer/crosslinker feed ratio. The microgels demonstrated a pH-dependent cleavage behavior that mimicked the pH-dependent hydrolysis profile of the acid-labile crosslinkers. Model biomacromolecules, i.e., Rhodamine B-labeled dextran and BSA were efficiently loaded into the microgels. The release of the biomolecules from p(HEMA) microgels was also found to be controllable by the pH of the environment similar to the particle degradation. The protein released from the microgels was observed to retain its structural stability. [source] Metastasis-associated gene expression profile of liver and subcutaneous lesions derived from mouse pheochromocytoma cellsMOLECULAR CARCINOGENESIS, Issue 4 2008Shoichiro Ohta Abstract The development of metastatic cancer is associated with overexpression or downregulation of specific genes and cell regulatory pathways. Some of these genes and pathways may be involved in invasion and dissemination of tumor cells, while others may promote seeding, survival or growth of cells at specific distant sites. In this investigation, gene expression profiles of nonmetastasizing tumors generated by injecting mouse pheochromocytoma cells (MPCs) subcutaneously were compared to those of liver tumors generated by injecting the cells intravenously. Both were compared to the cultured parental cell line. Tumors in the liver have a route of spread, anatomical distribution, and growth environment similar to naturally metastasizing pheochromocytomas, while intravenous injection of cells bypasses the initial steps of metastasis occurring spontaneously from a primary tumor. Eight genes were upregulated in liver tumors, 15 in subcutaneous tumors and seven in both compared to the cultured cells. Using quantitative real-time PCR, expression of five genes (Metap2, Reck, S100a4, Timp2, and Timp3) was verified as significantly lower in liver tumors than in subcutaneous tumors. Downregulation of these genes has been previously been associated with malignancy of pheochromocytomas. These findings indicate that different microenvironments can differentially affect the expression of metastasis-related genes in pheochromocytomas, and that overexpression or underexpression of these genes need not be present when the tumor cells are initially disseminated. The hepatic localization of tumors formed by intravenously injected MPC cells and the tumors' gene expression profile resembling that of naturally occurring pheochromocytoma metastases support the use of this model to study pheochromocytoma metastasis. © 2007 Wiley-Liss, Inc. [source] The biogeography of prediction error: why does the introduced range of the fire ant over-predict its native range?GLOBAL ECOLOGY, Issue 1 2007Matthew C. Fitzpatrick ABSTRACT Aim, The use of species distribution models (SDMs) to predict biological invasions is a rapidly developing area of ecology. However, most studies investigating SDMs typically ignore prediction errors and instead focus on regions where native distributions correctly predict invaded ranges. We investigated the ecological significance of prediction errors using reciprocal comparisons between the predicted invaded and native range of the red imported fire ant (Solenopsis invicta) (hereafter called the fire ant). We questioned whether fire ants occupy similar environments in their native and introduced range, how the environments that fire ants occupy in their introduced range changed through time relative to their native range, and where fire ant propagules are likely to have originated. Location, We developed models for South America and the conterminous United States (US) of America. Methods, We developed models using the Genetic Algorithm for Rule-set Prediction (GARP) and 12 environmental layers. Occurrence data from the native range in South America were used to predict the introduced range in the US and vice versa. Further, time-series data recording the invasion of fire ants in the US were used to predict the native range. Results, Native range occurrences under-predicted the invasive potential of fire ants, whereas occurrence data from the US over-predicted the southern boundary of the native range. Secondly, introduced fire ants initially established in environments similar to those in their native range, but subsequently invaded harsher environments. Time-series data suggest that fire ant propagules originated near the southern limit of their native range. Conclusions, Our findings suggest that fire ants from a peripheral native population established in an environment similar to their native environment, and then ultimately expanded into environments in which they are not found in their native range. We argue that reciprocal comparisons between predicted native and invaded ranges will facilitate a better understanding of the biogeography of invasive and native species and of the role of SDMs in predicting future distributions. [source] PM3-compatible zinc parameters optimized for metalloenzyme active sitesJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 14 2004Edward N. Brothers Abstract Recent studies have shown that semiempirical methods (e.g., PM3 and AM1) for zinc-containing compounds are unreliable for modeling structures containing zinc ions with ligand environments similar to those observed in zinc metalloenzymes. To correct these deficiencies a reparameterization of zinc at the PM3 level was undertaken. In this effort we included frequency corrected B3LYP/6-311G* zinc metalloenzyme ligand environments along with previously utilized experimental data. Average errors for the heats of formation have been reduced from 46.9 kcal/mol (PM3) to 14.2 kcal/mol for this new parameter set, termed ZnB for "Zinc, Biological." In addition, the new parameter sets predict geometries for the Bacillus fragilis active site model and other zinc metalloenzyme mimics that are qualitatively in agreement with high-level ab initio results, something existing parameter sets failed to do. © 2004 Wiley Periodicals, Inc. J Comput Chem 25: 1677,1692, 2004 [source] Simulation of the mean urban heat island using 2D surface parameters: empirical modelling, verification and extensionMETEOROLOGICAL APPLICATIONS, Issue 3 2009Bernadett Balázs Abstract The spatial distribution of the annual mean urban heat island (UHI) intensity was simulated applying empirical models based on datasets from urban areas of Szeged and Debrecen, using simple and easily determinable urban surface cover variables. These two cities are situated on the Alföld (Great Hungarian Plain) and have similar topographic and climatic conditions. Temperature field measurements were carried out, Landsat satellite images were evaluated, and then one- and multiple variable models were constructed using linear regression techniques. The selected multiple-parameter models were verified using independent datasets from three urban settlements. In order to obtain some impression of the mean UHI patterns in other cities with no temperature measurements available, the better model was extended to urban areas of four other cities situated in geographical environments similar to Szeged and Debrecen. The main shortcoming of typical empirical models, namely that they are often restricted to a specific location, is overcome by the obtained model since it is not entirely site but more region specific, and valid in a large and densely populated area with several settlements. Copyright © 2009 Royal Meteorological Society [source] | |||||||||||||