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1.
Prev Med Rep ; 13: 73-79, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30533348

RESUMO

Asthma is a major health threat and leading cause of chronic morbidity among children. Air pollutants have been linked to exacerbations and promotion of initial development of asthma. Extensive research already conducted assessing adverse health impacts associated with exposure to pollutants from vehicular traffic. However, little research conducted assessing exposure to pollutants stemming from goods movement industry, such as freight railyards. This study's purpose to assess potential association between residential proximity to major freight railyards and asthma-related emergency room (ER) visits in children. This study included children ≤14 yrs. old, living within 30-mile radius of one of 18 freight railyards in California, and having utilized emergency room services between 2007 and 2009, identified through California Office of Statewide Health Planning and Development (OSHPD) database. Logistic regression modeling with all 18 railyards, and models with top 5 polluting railyards, conducted to assess for potential association between asthma related ER visit (asthma vs. non-asthma visit) and railyard residential proximity. A total 109,645 asthma related ER visits identified, majority among low income, minority populations. Within 18 railyard model, children closest to railyard (0-5 miles) were at significant increased odds (OR = 1.15, 95%CI: 1.10-1.20) for asthma related ER visit and stronger odds observed for 5 top emitting railyards (OR = 1.40, 95%CI: 1.29-1.52). Our findings indicate a strong link between asthma ER visits for children and residential proximity to railyards, especially among low-income and minority communities. There's a critical need to better understand complex health risks for individuals residing in these communities and mitigation efforts for this vulnerable population.

2.
Ann Surg Oncol ; 26(3): 815-820, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30556120

RESUMO

BACKGROUND: OncotypeDX recurrence score (RS)® has been found to predict recurrence and disease-free survival in patients with node negative breast cancer. Whether RS is useful in guiding locoregional therapy decisions is unclear. We sought to evaluate the relationship between RS and lymph node burden. METHODS: Patients with invasive breast cancer who underwent sentinel lymph node dissection from 2010 to 2015 were identified from a prospectively maintained database. Patients were excluded if they were clinically node positive or if they received neoadjuvant chemotherapy. RS was classified as low (< 18), intermediate (18-30), or high (> 30). The association between RS, lymph node burden, and disease recurrence was evaluated. Statistical analyses were performed in R version 3.4.0; p < 0.05 was considered significant. RESULTS: A positive SLN was found in 168 (15%) of 1121 patients. Completion axillary lymph node dissection was performed in 84 (50%) of SLN-positive patients. The remaining 84 (50%) patients had one to two positive SLNs and did not undergo further axillary surgery. RS was low in 58.5%, intermediate in 32.6%, and high in 8.9%. RS was not associated with a positive SLN, number of positive nodes, maximum node metastasis size, or extranodal extension. The median follow-up was 23 months. High RS was not associated with locoregional recurrence (p = 0.07) but was significantly associated with distant recurrence (p = 0.0015). CONCLUSIONS: OncotypeDX RS is not associated with nodal burden in women with clinically node-negative breast cancer, suggesting that RS is not useful to guide decisions regarding extent of axillary surgery for these patients.


Assuntos
Biomarcadores Tumorais/genética , Neoplasias da Mama/patologia , Carcinoma Ductal de Mama/secundário , Testes Genéticos/métodos , Recidiva Local de Neoplasia/patologia , Linfonodo Sentinela/patologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Neoplasias da Mama/genética , Neoplasias da Mama/cirurgia , Carcinoma Ductal de Mama/genética , Carcinoma Ductal de Mama/cirurgia , Feminino , Seguimentos , Perfilação da Expressão Gênica , Humanos , Metástase Linfática , Pessoa de Meia-Idade , Recidiva Local de Neoplasia/genética , Recidiva Local de Neoplasia/cirurgia , Prognóstico , Estudos Prospectivos , Estudos Retrospectivos , Linfonodo Sentinela/metabolismo , Linfonodo Sentinela/cirurgia , Biópsia de Linfonodo Sentinela
3.
Eur J Cardiovasc Nurs ; 17(2): 178-185, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-28832179

RESUMO

BACKGROUND: A variety of educational interventions have been implemented to assist patients with heart failure to maintain their own health, develop self-care behaviours and decrease readmissions. AIMS: The purpose of this study was to determine the effectiveness of a multimedia educational intervention for patients with heart failure in reducing unplanned hospital readmissions. METHODS: The study, a randomised controlled trial in a large tertiary referral hospital in Australia, recruited 200 patients. Patients diagnosed with heart failure were randomly allocated 1:1 to usual education or a multimedia educational intervention. The multimedia approach began with an individual needs assessment to develop an educational plan. The educational intervention included viewing a DVD, and verbal discussion supported by a written manual with a teach-back evaluation strategy. The primary outcome was all-cause unplanned hospital readmission at 28 days, three months and 12 months post-recruitment. The secondary outcomes were changes in knowledge and self-care behaviours at three months and 12 months post-recruitment. RESULTS: At 12 months, data on 171 participants were analysed. There were 24 participants who had an unplanned hospital readmission in the intervention group compared to 44 participants in the control group ( p=0.005). The self-care educational intervention reduced the risk of readmission at 12 months by 30% (relative risk: 0.703; 95% confidence interval: 0.548-0.903). CONCLUSION: A targeted multimedia educational intervention can be effective in reducing all-cause unplanned readmissions for people with heart failure.


Assuntos
Conhecimentos, Atitudes e Prática em Saúde , Insuficiência Cardíaca/terapia , Educação de Pacientes como Assunto , Readmissão do Paciente , Autocuidado , Adulto , Idoso , Austrália , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Multimídia , Adulto Jovem
4.
Climacteric ; 19(3): 268-73, 2016 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-26940827

RESUMO

Background The climacteric phase of menopausal transition (perimenopause) is marked by reproductive hormone fluctuations and reduced cognitive capacity. Exercise enhances neurocognitive performance. However, auditory perceptual sensitivity has not been examined. Purpose This study aimed to determine the effect of aerobic exercise on the response speed (reaction time) and error rate during auditory processing among perimenopausal women. Methods Three pitches (500, 1000, and 2000 Hz) were used during a simple auditory discrimination task, which was performed before and after exercise. We included 14 perimenopausal women and 17 right-handed young women (aged 46-54 years and 18-22 years, respectively). To achieve similar exercise intensity in both groups, we proposed two types of physical activities for each group. Mixed models statistics were used to analyze the reaction time and error rate before and after training in the two groups. Results Perimenopausal women exhibited a significantly longer reaction time than young women during the baseline auditory discrimination task (p < 0.05) but not during the second test. The error rate decreased significantly after exercise among perimenopausal women (p < 0.05) but not among young women. Thus, exercise had a stronger beneficial influence on auditory plasticity or sensitivity for perimenopausal women than for young women. Conclusion The ability of aerobic exercise to modulate auditory neurocognitive performance differs between the two groups. Aerobic exercise improves auditory discrimination performance specifically for perimenopausal women. These results provide preliminary evidence concerning the acoustic features of middle-aged women, underscoring the importance of exercise for preventing decline in auditory cognitive function in perimenopausal women.


Assuntos
Percepção Auditiva/fisiologia , Cognição/fisiologia , Exercício Físico/fisiologia , Perimenopausa/fisiologia , Adolescente , Adulto , Feminino , Humanos , Pessoa de Meia-Idade , Tempo de Reação , Adulto Jovem
5.
Clin Radiol ; 69(5): 473-80, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24556468

RESUMO

AIM: To evaluate liver necro-inflammation and function by using gadoxetic acid-enhanced dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), with histological analysis as the reference standard. MATERIALS AND METHODS: Seventy-nine subjects (21 healthy subjects; 58 chronic hepatitis patients) who received gadoxetic acid-enhanced DCE-MRI were divided into three subgroups: no (A0, n = 31), mild (A1, n = 27), and moderate-severe (A2-A3, n = 21) activities. Two DCE-MRI models were measured: (1) a dual-input single-compartment model to obtain absolute arterial, portal venous, and total blood flow, arterial fraction (ART), distribution volume, and mean transit time; (2) a curve analysis method to obtain peak, slope, and AUC (area under curve). The serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels also obtained. Statistical testing included Kruskal-Wallis tests for continuous data, Pearson's correlation tests, and multiple linear regression analyses. RESULTS: Hepatic necro-inflammatory activity grades were significantly correlated with fibrotic stages, serum ALT level, ART and AUC. ART was helpful to predict the mild activity (≤ A1 versus >A1; Az = 0.728), whereas AUC could differentiate no activity from any activity (A0 versus >A0; Az = 0.703). Peak, slope and AUC were all associated with AST and ALT (p < 0.05). CONCLUSION: Gadoxetic acid-enhanced DCE-MRI parameters may be used to evaluate the severity of hepatic necro-inflammation and function.


Assuntos
Meios de Contraste , Gadolínio DTPA , Hepatite Crônica/enzimologia , Hepatite Crônica/patologia , Fígado/patologia , Imageamento por Ressonância Magnética , Imagem de Perfusão , Adulto , Alanina Transaminase/sangue , Área Sob a Curva , Aspartato Aminotransferases/sangue , China/epidemiologia , Feminino , Hepatite Crônica/imunologia , Humanos , Fígado/irrigação sanguínea , Fígado/enzimologia , Masculino , Pessoa de Meia-Idade , Necrose , Valor Preditivo dos Testes , Estudos Prospectivos , Padrões de Referência , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Índice de Gravidade de Doença
6.
Oncogene ; 33(10): 1265-73, 2014 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-23524582

RESUMO

The stromal compartment surrounding epithelial-derived pancreatic tumors is thought to have a key role in the aggressive phenotype of this malignancy. Emerging evidence suggests that cancer-associated fibroblasts (CAFs), the most abundant cells in the stroma of pancreatic tumors, contribute to the tumor's invasion, metastasis and resistance to therapy, but the precise molecular mechanisms that regulate CAFs behavior are poorly understood. In this study, we utilized immortalized human pancreatic CAFs to investigate molecular pathways that control the matrix-remodeling and invasion-promoting activity of CAFs. We showed previously that palladin, an actin-associated protein, is expressed at high levels in CAFs of pancreatic tumors and other solid tumors, and also in an immortalized line of human CAFs. In this study, we found that short-term exposure of CAFs to phorbol esters reduced the number of stress fibers and triggered the appearance of individual invadopodia and invadopodial rosettes in CAFs. Molecular analysis of invadopodia revealed that their composition resembled that of similar structures (that is, invadopodia and podosomes) described in other cell types. Pharmacological inhibition and small interfering RNA knockdown experiments demonstrated that protein kinase C, the small GTPase Cdc42 and palladin were necessary for the efficient assembly of invadopodia by CAFs. In addition, GTPase activity assays showed that palladin contributes to the activation of Cdc42. In mouse xenograft experiments using a mixture of CAFs and tumor cells, palladin expression in CAFs promoted the rapid growth and metastasis of human pancreatic tumor cells. Overall, these results indicate that high levels of palladin expression in CAFs enhance their ability to remodel the extracellular matrix by regulating the activity of Cdc42, which in turn promotes the assembly of matrix-degrading invadopodia in CAFs and tumor cell invasion. Together, these results identify a novel molecular signaling pathway that may provide new molecular targets for the inhibition of pancreatic cancer metastasis.


Assuntos
Carcinoma Ductal Pancreático/metabolismo , Extensões da Superfície Celular/metabolismo , Proteínas do Citoesqueleto/fisiologia , Fibroblastos/metabolismo , Neoplasias Pancreáticas/metabolismo , Fosfoproteínas/fisiologia , Animais , Carcinoma Ductal Pancreático/patologia , Movimento Celular , Técnicas de Cocultura , Matriz Extracelular/metabolismo , Fibroblastos/patologia , Humanos , Camundongos , Invasividade Neoplásica , Transplante de Neoplasias , Neoplasias Pancreáticas/patologia , Células Estreladas do Pâncreas/metabolismo , Células Estreladas do Pâncreas/patologia , Transporte Proteico , Acetato de Tetradecanoilforbol/farmacologia , Proteína cdc42 de Ligação ao GTP/metabolismo
7.
Pharmacopsychiatry ; 46(2): 77-82, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-23037950

RESUMO

INTRODUCTION: Smoking is a leading global cause of avoidable mortality. It has been reported that the nicotinic acetylcholine receptor (CHRNA4 and CHRNB2) genes might be associated with smoking behavior in several ethnic populations. However, no study between the 2 genes and nicotine dependence (ND) using a Japanese population has been reported. METHODS: We examined the association between ND and 5 single nucleotide polymorphisms (SNPs) within the CHRNA4 and 3 SNPs within the CHRNB2 using a well characterized sample of 558 Japanese healthy male workers with a relatively homogeneous background. The Fagerström test for nicotine dependence (FTND) was used to quantify the degree of ND. Additionally, we explored the effect of gene-gene interactions of the 2 genes on ND. RESULTS: We found CHRNB2 rs4845652 genotypes to be associated with FTND scores under an additive genetic model: rs4845652 T-allele carriers had lower ND levels (p=0.038; when adjusted for smoking duration: p=0.052). Furthermore, we demonstrated a possible gene-gene interaction of CHRNA4 and CHRNB2 on ND in a dose-dependent manner: those smokers with CHRNA4 rs1044397 GG or GA genotypes along with CHRNB2 rs4845652 CC genotype are likely to demonstrate higher ND scores. DISCUSSION: These findings suggest that CHRNB2 rs4845652 T-allele carriers may be associated with lower levels of ND, and that certain allelic combinations of CHRNA4 and CHRNB2 might be correlated with higher ND levels. This preliminary study has certain limitations (issues such as sample size/power and multiple testing) that need to be taken into account, and the present work thus has an experimental nature.


Assuntos
Povo Asiático/genética , Predisposição Genética para Doença/genética , Receptores Nicotínicos/genética , Tabagismo/genética , Adulto , Alelos , Povo Asiático/psicologia , Epistasia Genética/genética , Humanos , Masculino , Polimorfismo de Nucleotídeo Único/genética
8.
Abdom Imaging ; 38(6): 1383-90, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23232580

RESUMO

OBJECTIVE: To evaluate and describe the computed tomography features of pure acinar cell carcinoma (ACC) and its liver metastases. METHODS: Thirty patients were evaluated. Two radiologists evaluated imaging findings for each tumor for size, location, internal density, enhancement, tumor calcifications, pancreatic, and common biliary ductal obstructions and metastases. RESULTS: 70 % were male. Fourteen tumors were located in the pancreatic head, 14 in the tail, one in the neck, and one in the uncinate process. Abdominal pain was the most common presenting symptom (93 %), 20 % had pancreatitis and 17 % had obstructive jaundice. The average tumor size was 7 cm, 97 % of tumors were solid, well circumscribed (73 %); isodense to normal pancreatic parenchyma (40 %) on the non-contrast study, hypodense on the arterial (47 %), and hypodense on the portal venous (37 %) phase. 30 % patients had pancreatic ductal dilation, 10 % had pancreatic ductal ingrowth, 6 % had calcifications, and 20 % had central necrosis, and 31 % (5/16) showed biliary ductal dilation. At presentation, 50 % had metastatic adenopathy and 40 % patients had liver metastases, which typically were well circumscribed, hypoattenuating to the hepatic parenchyma on all the phases of contrast enhancement and had a lobulated margin. CONCLUSION: ACCs of the pancreas often present as large, well circumscribed, solid masses commonly in males. Despite their large size, they may not cause CBD obstruction.


Assuntos
Carcinoma de Células Acinares/diagnóstico por imagem , Neoplasias Hepáticas/diagnóstico por imagem , Neoplasias Pancreáticas/diagnóstico por imagem , Tomografia Computadorizada por Raios X/métodos , Adulto , Idoso , Idoso de 80 Anos ou mais , Carcinoma de Células Acinares/secundário , Meios de Contraste , Feminino , Humanos , Neoplasias Hepáticas/secundário , Metástase Linfática , Masculino , Pessoa de Meia-Idade , Neoplasias Pancreáticas/patologia , Ácidos Tri-Iodobenzoicos
9.
Pharmacogenomics J ; 12(2): 156-64, 2012 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-20714340

RESUMO

Antipsychotic-induced weight gain has emerged as a serious complication in the treatment of patients with most antipsychotics. We have conducted the first in-depth examination of dopamine receptor genes in antipsychotic-induced weight gain. A total of 206 patients (139 of European descent and 56 African Americans) who underwent treatment for chronic schizophrenia or schizoaffective disorder were evaluated after on average over 6 weeks of treatment. Thirty-six tag single nucleotide polymorphisms (SNPs) and one variable-number tandem repeat, spanning the five dopamine receptor genes (DRD1-DRD5) were analyzed. In the total sample, we found a nominally significant association between the DRD2 rs1079598 marker and weight change using a cutoff of 7% gain (P=0.03). When stratifying the sample according to ethnicity and antipsychotics with highest risk for weight gain, we found significant associations in three DRD2 SNPs: rs6277 (C957T), rs1079598 and rs1800497 (TaqIA). The other genes were primarily negative. We provide evidence that dopamine receptor DRD2 gene variants might be associated with antipsychotic-induced weight gain in chronic schizophrenia patients.


Assuntos
Antipsicóticos/efeitos adversos , Transtornos Psicóticos/tratamento farmacológico , Receptores Dopaminérgicos/genética , Esquizofrenia/tratamento farmacológico , Aumento de Peso , Adulto , Antipsicóticos/uso terapêutico , Primers do DNA , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Reação em Cadeia da Polimerase , Polimorfismo de Nucleotídeo Único
10.
Indoor Air ; 20(3): 235-45, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-20573123

RESUMO

UNLABELLED: This study investigated the thermal sensation of elderly people in Taiwan, older than 60 years, in indoor microclimate at home, and their requirements for establishing thermal comfort. The study was conducted using both a thermal sensation questionnaire and measurement of indoor climatic parameters underlying the thermal environment. Survey results were compared with those reported by Cheng and Hwang (2008, J. Tongji Univ., 38, 817-822) for non-elders to study the variation between different age groups in requirements of indoor thermal comfort. The results show that the predominant strategy of thermal adaptation for elders was window-opening in the summer and clothing adjustment in the winter. The temperature of thermal neutrality was 25.2 degrees C and 23.2 degrees C for the summer and the winter, respectively. Logistically regressed probit modeling on percentage of predicted dissatisfied (PPD) against mean thermal sensation vote revealed that the sensation votes corresponding to a PPD of 20% were +/- 0.75 for elders, about +/- 0.10 less than the levels projected by ISO 7730 model. The range of operative temperature for 80% thermal acceptability for elders in the summer was 23.2-27.1 degrees C, narrower than the range of 23.0-28.6 degrees C reported for non-elders. This is likely a result of a difference in the selection of adaptive strategies. PRACTICAL IMPLICATIONS: Taiwan in the last decade has seen a rapid growth in the elderly population in its societal structure, and as such the quality of indoor thermal comfort increasingly concerns the elderly people. This study presents the results from field-surveying elders residing in major geographical areas of Taiwan, and discusses the requirements of these elders for indoor thermal comfort in different seasons. Through a comparison with the requirements by non-elders, this study demonstrates the unique sensitivity of elders toward indoor thermal quality and the selection of adaptive strategies that need to be considered when a thermal comfort zone is attempted in a household of members consisting of different age groups.


Assuntos
Adaptação Fisiológica , Regulação da Temperatura Corporal/fisiologia , Habitação , Sensação Térmica/fisiologia , Idoso , Ar Condicionado , Estudos de Casos e Controles , Coleta de Dados , Feminino , Humanos , Umidade , Masculino , Pessoa de Meia-Idade , Inquéritos e Questionários , Taiwan , Ventilação
11.
Pharmacogenomics J ; 10(3): 200-18, 2010 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-20029384

RESUMO

D2 blockade has been implicated in having a central role in antipsychotic response. However, treatment refractoriness, in spite of complete D2 blockade, as well as the efficacy of clozapine (CLZ) in a portion of this patient population, indicates the involvement of other factors as well. Several lines of evidence suggest a role for D3. Furthermore, an earlier meta-analysis by Jönsson et al. (2003) (n=233) suggested a role for genetic variation in the D3 gene. Relevant to this study, Jönsson et al. found the Ser allele of the D3 serine-to-glycine substitution at amino acid position 9 (Ser9Gly) polymorphism to be associated with worse CLZ response compared with the Gly allele. In this study, we attempt to validate these findings by performing a meta-analysis in a much larger sample (n=758). Eight other variants were also tested in our own sample to explore the possible effect of other regions of the gene. We report a negative but consistent trend across individual studies in our meta-analysis for the DRD3 Ser allele and poor CLZ response. A possible minor role for this single-nucleotide polymorphism cannot be disregarded, as our sample size may have been insufficient. Other DRD3 variants and haplotypes of possible interest were also identified for replication in future studies.


Assuntos
Antipsicóticos/uso terapêutico , Clozapina/uso terapêutico , Receptores de Dopamina D3/genética , Esquizofrenia/tratamento farmacológico , Adulto , Negro ou Afro-Americano , Substituição de Aminoácidos , Feminino , Haplótipos , Humanos , Desequilíbrio de Ligação , Masculino , Polimorfismo de Nucleotídeo Único , População Branca
12.
J Microsc ; 234(1): 9-15, 2009 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19335452

RESUMO

Biarsenical-tetracysteine fluorescent protein tagging has been effectively used in a variety of cell types. It has the advantage of requiring a much smaller peptide alteration to existing proteins than fusion to green fluorescent protein (GFP) or monomeric red fluorescent protein (mRFP). However, there are no reports of the tetracysteine tagging system being used in Dictyostelium. In order to establish this tagging system in Dictyostelium, the filamin gene (FLN) was modified to express a C-terminal tetracysteine sequence and then transfected into cells. After addition of either FlAsH-EDT(2) or ReAsH-EDT(2), the fluorescence intensity of cells increased in a time-dependent manner and reached a plateau after 3 h of incubation. ReAsH had a much stronger and more specifically localized fluorescent signal compared with FlAsH. After removal of the ReAsH-EDT(2) reagent, the fluorescence signal remained detectable for at least 24 h. The localization of filamin labelled by ReAsH was similar to that of an FLN-mRFP fusion protein, but the fluorescence signal from the ReAsH-labelled protein was stronger. Our findings suggest that the ReAsH-tetracysteine tagging system can be a useful alternative for in vivo protein tagging in Dictyostelium.


Assuntos
Arsenicais/metabolismo , Proteínas Contráteis/metabolismo , Dictyostelium/metabolismo , Proteínas dos Microfilamentos/metabolismo , Oxazinas/metabolismo , Proteínas de Protozoários/metabolismo , Coloração e Rotulagem/métodos , Animais , Proteínas Contráteis/genética , Cisteína/genética , Dictyostelium/genética , Filaminas , Fluoresceínas/metabolismo , Fluorescência , Proteínas dos Microfilamentos/genética , Compostos Organometálicos/metabolismo , Proteínas de Protozoários/genética
15.
Phys Rev Lett ; 93(16): 166101, 2004 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-15525006

RESUMO

We find that less than 0.01 monolayer of S can enhance surface self-diffusion on Cu(111) by several orders of magnitude. The measured dependence of two-dimensional island decay rates on S coverage (theta(S)) is consistent with the proposal that Cu3S3 clusters are responsible for the enhancement. Unexpectedly, the decay and ripening are diffusion limited with very low and very high theta(S) but not for intermediate theta(S). To explain this result we propose that surface mass transport in the intermediate region is limited by the rate of reaction to form Cu3S3 clusters on the terraces.

16.
Phys Rev Lett ; 92(11): 116102, 2004 Mar 19.
Artigo em Inglês | MEDLINE | ID: mdl-15089153

RESUMO

We report an experimental (scanning tunneling microscopy) and theoretical (embedded atom method) study of a heterophase interface reconstruction between Ag(111) and Ru(0001). Despite the large 7% mismatch, the second layer of Ag from the Ru exhibits a hexagonal structure with Ag bulk spacing, providing a close match to bulk Ag. The first layer of Ag (next to Ru) is reconstructed in a highly symmetrical and regular structure containing monolayer long threading dislocations. We argue that this structure may generally occur to relieve strain in a certain class of heterophase interfaces.

17.
Phys Rev Lett ; 92(10): 106101, 2004 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-15089218

RESUMO

Deposition of S onto a monolayer of Ag/Ru(0001) transforms the herringbone pattern of the clean Ag film into a strikingly regular array of 2D-vacancy islands [Nature (London) 397, 238 (1999)]]. Time-resolved scanning tunneling microscopy reveals that this nanometer-scale restructuring occurs by a cooperative mechanism involving the sequential formation of triangular regions with fcc and hcp stacking. Using a 2D Frenkel-Kontorova model, we can simulate the creation of these triangular building blocks via basic dislocation motions and reactions.

18.
Surg Endosc ; 18(11): 1631-5, 2004 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-15931476

RESUMO

BACKGROUND: Small bowel obstruction after laparoscopic Roux-en-Y gastric bypass is not a rare complication, occurring in approximately 3% of patients. The goal of this study was to review the causes and timing of small bowel obstruction as an aid to diagnosis, treatment, and prevention. METHODS: The records of consecutive patients who underwent laparoscopic Roux-en-Y gastric bypass at the authors' center from 4/99 to 7/03 were retrospectively reviewed. All the patients had a laparoscopic handsewn gastrojejunostomy and a stapled jejunojejunostomy. The Roux limb was placed retrocolically in the first 405 patients and antecolically in the next 1,310 patients. RESULTS: Altogether, 1,715 patients underwent a total laparoscopic Roux-en-Y gastric bypass at the authors' bariatric center. In 51 patients, 55 small bowel obstructions occurred (3%) during a median follow-up period of 21 months (range, 1-52 months). Small bowel obstruction developed in 27 (7%) of the retrocolic patients, as compared with 24 (2%) of the antecolic patients (p < 0.001, chi-square). The causes of small bowel obstruction were adhesive bands (n = 14), obstruction at the jejunojejunostomy from kinking or narrowing (n = 13), internal hernia or external compression at the transverse mesocolon (n = 11), internal hernia through the jejunal mesentery (n = 8) incarcerated abdominal wall hernia (n = 4), and other (n = 5). For patients in whom small bowel obstruction developed in the first 3 weeks after their bypass surgery bowel resection was required in 19 of 24 patients, as compared with 6 of 31 patients in whom obstruction develop after 3 weeks (p < 0.001, chi-square). CONCLUSIONS: Early small bowel obstructions tend to result from technical problems with the Roux limb and require revision of the bypass or small bowel resection significantly more often than late obstructions. The latter group of obstructions usually result from adhesions or hernias, which could be handled laparoscopically without bowel resection. The position of the Roux limb (retrocolic vs antecolic) appeared to influence the incidence of small bowel obstruction. In the current series, changing the position of the jejunal bypass limb from retrocolic to antecolic significantly decreased the overall incidence of small bowel obstruction because it eliminated one of the most common sites for obstruction: the mesocolon.


Assuntos
Derivação Gástrica/efeitos adversos , Derivação Gástrica/métodos , Obstrução Intestinal/etiologia , Laparoscopia , Humanos , Obstrução Intestinal/epidemiologia , Intestino Delgado , Estudos Retrospectivos
19.
Phys Rev E Stat Nonlin Soft Matter Phys ; 68(2 Pt 2): 026704, 2003 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-14525145

RESUMO

In this study, two fast and accurate methods of inverse iteration with multigrid acceleration are developed to compute band structures of photonic crystals of general shape. In particular, we report two-dimensional photonic crystals of silicon air with an optimal full band gap of gap-midgap ratio Deltaomega/omega(mid)=0.2421, which is 30% larger than ever reported in the literature. The crystals consist of a hexagonal array of circular columns, each connected to its nearest neighbors by slender rectangular rods. A systematic study with respect to the geometric parameters of the photonic crystals was made possible with the present method in drawing a three-dimensional band-gap diagram with reasonable computing time.

20.
Phys Rev Lett ; 89(3): 036101, 2002 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-12144406

RESUMO

Annealed submonolayer CoAg/Ru(0001) films form an alloy with a structure that contains droplets of Ag surrounded by Co [G. E. Thayer, V. Ozolins, A. K. Schmid, N. C. Bartelt, M. Asta, J. J. Hoyt, S. Chiang, and R. Q. Hwang, Phys. Rev. Lett. 86, 660 (2001)]. To understand how surface stress contributes to the formation of this structure, we use scanning tunneling microscopy to extract atomic displacements at the boundaries between regions of Co and Ag. Comparing our measurements to Frenkel-Kontorova model calculations, we show how stress due to lattice mismatch contributes to the formation of the alloy droplet structure. In particular, we quantitatively evaluate how competing strain and chemical energy contributions determine surface structure.

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