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1.
J Chem Inf Model ; 64(4): 1377-1393, 2024 02 26.
Artigo em Inglês | MEDLINE | ID: mdl-38345917

RESUMO

The influence of distance restraints from chemical cross-link mass spectroscopy (XL-MS) on the quality of protein structures modeled with the coarse-grained UNRES force field was assessed by using a protocol based on multiplexed replica exchange molecular dynamics, in which both simulated and experimental cross-link restraints were employed, for 23 small proteins. Six cross-links with upper distance boundaries from 4 Å to 12 Å (azido benzoic acid succinimide (ABAS), triazidotriazine (TATA), succinimidyldiazirine (SDA), disuccinimidyl adipate (DSA), disuccinimidyl glutarate (DSG), and disuccinimidyl suberate (BS3)) and two types of restraining potentials ((i) simple flat-bottom Lorentz-like potentials dependent on side chain distance (all cross-links) and (ii) distance- and orientation-dependent potentials determined based on molecular dynamics simulations of model systems (DSA, DSG, BS3, and SDA)) were considered. The Lorentz-like potentials with properly set parameters were found to produce a greater number of higher-quality models compared to unrestrained simulations than the MD-based potentials, because the latter can force too long distances between side chains. Therefore, the flat-bottom Lorentz-like potentials are recommended to represent cross-link restraints. It was also found that significant improvement of model quality upon the introduction of cross-link restraints is obtained when the sum of differences of indices of cross-linked residues exceeds 150.


Assuntos
Simulação de Dinâmica Molecular , Proteínas , Conformação Proteica , Proteínas/química
2.
Asian Pac Isl Nurs J ; 8: e49493, 2024 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-38277216

RESUMO

BACKGROUND: During the COVID-19 pandemic, many community-based organizations serving Asian Americans pivoted to provide web-based care and social services. Asian American community leaders in the United States Pacific Northwest, including Asian Health & Service Center expressed that there are older immigrant adults who experienced backlash from discrimination, fear, and anxiety owing in part to anti-Asian hate and isolation, including from infection precautions. Pivoting supported staying safe from COVID-19 transmission and anti-Asian hate crimes. OBJECTIVE: This study aims to examine the readiness of diverse groups of older Asian American immigrant adults (Chinese, Koreans, and Vietnamese) to use a web-based senior center, including technology access and telehealth use, and to identify the psychosocial health impacts that a web-based senior center could be positioned to meet. METHODS: A community-based participatory research approach was used to conduct a cross-sectional survey study in an Asian-based health and service center in 2022. We selected surveys from the National Institutes of Health-supported PhenX Toolkit. Analyses were performed using R software. RESULTS: There was an 88.2% (216/245) response rate. Overall, 39.8% (86/216) of participants were Chinese, 25% (54/216) were Korean, and 24.5% (53/216) were Vietnamese. There were significant group differences in mobile data plans (P=.0005). Most had an unlimited mobile data plan (38/86, 44% Chinese; 39/54, 72% Koreans; 25/53, 47% Vietnamese). Significant group differences existed regarding whether they started using a new electronic device to communicate with friends or family after the COVID-19 outbreak (P=.0005); most were Korean participants (31/54, 57%). For written text and audio or video apps, most Chinese participants used WeChat (65/85, 76%; 57/84, 68%, respectively), most Koreans used KakaoTalk (49/54, 91%; 49/54, 91%, respectively), and most Vietnamese used Facebook Messenger for written text (32/50, 64%) and Apple Face Time (33/50, 66%) or Facebook Messenger (31/50, 62%) for audio or video. Significant group differences existed regarding whether to try telehealth (P=.0005); most Vietnamese expressed that they would never consider it (41/53, 77%). Significant group differences existed regarding how well they were able to concentrate (χ22=44.7; P<.0001); Chinese participants reported a greater inability (median 5, IQR 4-6). With regard to difficulties in life experiences (χ22=51; P<.0001), the median was 6 (IQR 5-7) for the Vietnamese group. Significant group differences existed in having had a family/household member's salary, hours, and contracts reduced (P=.0005) and having had a family/household member or friend fallen physically ill (P=.0005)-most Vietnamese (15/53, 28%) and Korean participants (10/53, 19%). CONCLUSIONS: To build an efficacious, web-based senior center with web-based care and social service options, more older adults need access to the internet and education about using technology-enabled communication devices. Addressing the unique psychosocial impacts of the COVID-19 pandemic on each group could improve health equity. The strength of the participating older adults was observed and honored.

3.
JAMA Ophthalmol ; 141(7): 641-649, 2023 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-37227703

RESUMO

Importance: The presence of diabetic macular ischemia (DMI) on optical coherence tomography angiography (OCTA) images predicts diabetic retinal disease progression and visual acuity (VA) deterioration, suggesting an OCTA-based DMI evaluation can further enhance diabetic retinopathy (DR) management. Objective: To investigate whether an automated binary DMI algorithm using OCTA images provides prognostic value on DR progression, diabetic macular edema (DME) development, and VA deterioration in a cohort of patients with diabetes. Design, Setting, and Participants: In this cohort study, DMI assessment of superficial capillary plexus and deep capillary plexus OCTA images was performed by a previously developed deep learning algorithm. The presence of DMI was defined as images exhibiting disruption of fovea avascular zone with or without additional areas of capillary loss, while absence of DMI was defined as images presented with intact fovea avascular zone outline and normal distribution of vasculature. Patients with diabetes were recruited starting in July 2015 and were followed up for at least 4 years. Cox proportional hazards models were used to evaluate the association of the presence of DMI with DR progression, DME development, and VA deterioration. Analysis took place between June and December 2022. Main Outcomes and Measures: DR progression, DME development, and VA deterioration. Results: A total of 321 eyes from 178 patients were included for analysis (85 [47.75%] female; mean [SD] age, 63.39 [11.04] years). Over a median (IQR) follow-up of 50.41 (48.16-56.48) months, 105 eyes (32.71%) had DR progression, 33 eyes (10.28%) developed DME, and 68 eyes (21.18%) had VA deterioration. Presence of superficial capillary plexus-DMI (hazard ratio [HR], 2.69; 95% CI, 1.64-4.43; P < .001) and deep capillary plexus-DMI (HR, 3.21; 95% CI, 1.94-5.30; P < .001) at baseline were significantly associated with DR progression, whereas presence of deep capillary plexus-DMI was also associated with DME development (HR, 4.60; 95% CI, 1.15-8.20; P = .003) and VA deterioration (HR, 2.12; 95% CI, 1.01-5.22; P = .04) after adjusting for age, duration of diabetes, fasting glucose, glycated hemoglobin, mean arterial blood pressure, DR severity, ganglion cell-inner plexiform layer thickness, axial length, and smoking at baseline. Conclusions and Relevance: In this study, the presence of DMI on OCTA images demonstrates prognostic value for DR progression, DME development, and VA deterioration.


Assuntos
Diabetes Mellitus , Retinopatia Diabética , Edema Macular , Humanos , Feminino , Pessoa de Meia-Idade , Masculino , Retinopatia Diabética/fisiopatologia , Edema Macular/fisiopatologia , Angiofluoresceinografia/métodos , Tomografia de Coerência Óptica/métodos , Estudos de Coortes , Inteligência Artificial , Capilares/fisiopatologia , Estudos Retrospectivos , Acuidade Visual , Progressão da Doença , Isquemia/diagnóstico
4.
Asian Pac Isl Nurs J ; 7: e43150, 2023 Jan 11.
Artigo em Inglês | MEDLINE | ID: mdl-36648292

RESUMO

BACKGROUND: Asian American (AA) community leaders, Native Hawaiian/Pacific Islander (NH/PI) community leaders, and allies in the United States Pacific Northwest expressed concern that there are families and children from AA communities and NH/PI communities who experience and witness acts of xenophobia and racism. This can cause racial trauma. The long-time practice of aggregating AA and NH/PI data contributes to erasure and makes it challenging to advance health equity, such as allocating resources. According to AAPI Data's long-awaited report in June 2022, there are over 24 million AAs and 1.6 million NHs/PIs in the United States, growing by 40% and 30%, respectively, between 2010 and 2020. Philanthropic investments have not kept up with this substantive increase. The National Academies of Sciences, Engineering, and Medicine emphasized the need for effective partnerships to advance the health and well-being of individuals and communities in antiracism and system-level research. OBJECTIVE: The aim of this community-based participatory research qualitative description study was to identify perceptions and experiences regarding racial discrimination, race-based stress, and racial trauma; intergenerational healing and resiliency; and sharing the body with science from key informants of an academic and community partnership to inform antiracism coalition work. This partnership includes academic researchers and community leaders from community-based organizations and a health care organization serving immigrant and marginalized communities, including AAs and NHs/PIs in the United States Pacific Northwest. METHODS: In total, 10 key informants joined 1 of 2 participatory group discussions via videoconference for 2 hours in 2022. We used a semistructured and open-ended group interview guide. A qualitative participatory group-level assessment was conducted with the key informants and transcribed. Interpretations and meanings of the main points and the main themes were reflected upon, clarified, and verified with the key informants in real time. The field note-based data transcripts were manually coded using conventional content analysis. Reflexivity was used. RESULTS: There were 6 main themes: prejudice plus power in racism definition and working in solidarity to counter lateral oppression/false sense of security, microaggression as multilayers, "not assimilationist by nature" and responding differently to white superiority, intergenerational- and identity-related trauma, what is healing among People of Color and through a lens of resiliency and intergenerational connection and knowledge, and mistrust and fear in the research and health care systems surrounding intentions of the body. CONCLUSIONS: The themes highlight the importance of internal and intergenerational healing from racial trauma and the need for solidarity among communities of color to combat white supremacy and colonization. This work was foundational in an ongoing effort to dismantle racism and uplift the community voice through a cross-sector academic and community partnership to inform antiracism coalition work.

5.
Sci Rep ; 12(1): 4876, 2022 03 22.
Artigo em Inglês | MEDLINE | ID: mdl-35319021

RESUMO

Despite improvements in medical care, the burden of sepsis remains high. In this study, we evaluated the incremental cost associated with postoperative sepsis and the impact of postoperative sepsis on clinical outcomes among surgical patients in Vietnam. We used the national database that contained 1,241,893 surgical patients undergoing seven types of surgery. We controlled the balance between the groups of patients using propensity score matching method. Generalized gamma regression and logistic regression were utilized to estimate incremental cost, readmission, and reexamination associated with postoperative sepsis. The average incremental cost associated with postoperative sepsis was 724.1 USD (95% CI 553.7-891.7) for the 30 days after surgery, which is equivalent to 28.2% of the per capita GDP in Vietnam in 2018. The highest incremental cost was found in patients undergoing cardiothoracic surgery, at 2,897 USD (95% CI 530.7-5263.2). Postoperative sepsis increased patient odds of readmission (OR = 6.40; 95% CI 6.06-6.76), reexamination (OR = 1.67; 95% CI 1.58-1.76), and also associated with 4.9 days longer of hospital length of stay among surgical patients. Creating appropriate prevention strategies for postoperative sepsis is extremely important, not only to improve the quality of health care but also to save health financial resources each year.


Assuntos
Readmissão do Paciente , Sepse , Bases de Dados Factuais , Humanos , Tempo de Internação , Complicações Pós-Operatórias/epidemiologia , Estudos Retrospectivos , Fatores de Risco , Sepse/epidemiologia , Vietnã/epidemiologia
6.
Biomolecules ; 11(4)2021 04 18.
Artigo em Inglês | MEDLINE | ID: mdl-33919640

RESUMO

The self-assembly of amyloidogenic peptides and proteins into fibrillar structures has been intensively studied for several decades, because it seems to be associated with a number of neurodegenerative diseases, such as Alzheimer's and Parkinson's disease. Therefore, understanding the molecular mechanisms of this phenomenon is important for identifying an effective therapy for the corresponding diseases. Protein aggregation in living organisms very often takes place on surfaces like membranes and the impact of a surface on this process depends not only on the surface chemistry but also on its topology. Our goal was to develop a simple lattice model for studying the role of surface roughness in the aggregation kinetics of polypeptide chains and the morphology of aggregates. We showed that, consistent with the experiment, an increase in roughness slows down the fibril formation, and this process becomes inhibited at a very highly level of roughness. We predicted a subtle catalytic effect that a slightly rough surface promotes the self-assembly of polypeptide chains but does not delay it. This effect occurs when the interaction between the surface and polypeptide chains is moderate and can be explained by taking into account the competition between energy and entropy factors.


Assuntos
Proteínas Amiloidogênicas/química , Humanos , Modelos Teóricos , Método de Monte Carlo , Polimerização , Propriedades de Superfície
7.
PLoS One ; 15(12): e0243889, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33362233

RESUMO

OBJECTIVE: To estimate the incubation period of Vietnamese confirmed COVID-19 cases. METHODS: Only confirmed COVID-19 cases who are Vietnamese and locally infected with available data on date of symptom onset and clearly defined window of possible SARS-CoV-2 exposure were included. We used three parametric forms with Hamiltonian Monte Carlo method for Bayesian Inference to estimate incubation period for Vietnamese COVID-19 cases. Leave-one-out Information Criterion was used to assess the performance of three models. RESULTS: A total of 19 cases identified from 23 Jan 2020 to 13 April 2020 was included in our analysis. Average incubation periods estimated using different distribution model ranged from 6.0 days to 6.4 days with the Weibull distribution demonstrated the best fit to the data. The estimated mean of incubation period using Weibull distribution model was 6.4 days (95% credible interval (CrI): 4.89-8.5), standard deviation (SD) was 3.05 (95%CrI 3.05-5.30), median was 5.6, ranges from 1.35 to 13.04 days (2.5th to 97.5th percentiles). Extreme estimation of incubation periods is within 14 days from possible infection. CONCLUSION: This analysis provides evidence for an average incubation period for COVID-19 of approximately 6.4 days. Our findings support existing guidelines for 14 days of quarantine of persons potentially exposed to SARS-CoV-2. Although for extreme cases, the quarantine period should be extended up to three weeks.


Assuntos
COVID-19/epidemiologia , Período de Incubação de Doenças Infecciosas , Quarentena , SARS-CoV-2/patogenicidade , Adulto , Teorema de Bayes , COVID-19/transmissão , COVID-19/virologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Método de Monte Carlo , Vietnã/epidemiologia
8.
Risk Manag Healthc Policy ; 13: 2149-2158, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33116993

RESUMO

BACKGROUND: Attitudes and beliefs could be associated with the low number of vaccinations in low- to middle-income countries such as Vietnam. This study aims to describe ways to develop and assess the attitudes towards Hepatitis B vaccination. METHODS: A mixed-method study was carried out between April 2015 and July 2017. Qualitative data were gathered via semi-structured interviews and focus group discussions. The data were then analyzed thematically into four domains of the Health Belief Model (HBM) in order to design the structured questionnaire. The quantitative strand was followed by the evaluation of the reliability and the construct validity, for which data were obtained after interviewing 768 parents whose children aged from 12 to 24 months, who were receiving the vaccines as part of the Expanded Programme on Immunization (EPI) schedules at the Commune Health Centers. RESULTS: The findings showed the content validity index value of 13 items ranged from 0.86 to 1.00. The factor analyses showed that 11 items remained in the final questionnaire after deleting 2 problematic items due to no relation to the total scales and revealed four factors (perceived susceptibility, perceived severity, perceived benefits, perceived barriers) that jointly accounted for 62.1% of the observed variances. All four factors have good internal consistency with a total Cronbach's alpha of 0.735. A confirmatory factor analysis demonstrated the proposed factor model which fits well in four domains of HBM. CONCLUSION: Attitude scales for Hepatitis B vaccination based on HBM have been developed. This has confirmed to be a valid and reliable instrument that might be useful in assessing parents' attitudes regarding Hepatitis B vaccination and may be used to promote interventions within the increasing vaccination coverage for Vietnamese children.

9.
Cancer Cytopathol ; 128(12): 895-904, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32931161

RESUMO

BACKGROUND: The purpose of the current study was to examine the impact of coronavirus disease 2019 (COVID-19) on various aspects of cytology practice in the Asia-Pacific region. METHODS: An online questionnaire was distributed to cytopathology laboratories in 24 Asia-Pacific countries to explore the impact of restrictive measures on access to health care, use of general and personal protective equipment (PPE), and changes in cytology workflow and workload from February to April 2020. RESULTS: A total of 167 cytopathology laboratories from 24 countries responded to the survey; the majority reported that restrictive measures that limited the accessibility of health care services had been implemented in their cities and/or countries (80.8%) and their hospitals (83.8%). The respondents noted that COVID-19 had an impact on the cytologic workflow as well as the workload. Approximately one-half of the participants reported the implementation of new biosafety protocols (54.5%) as well as improvements in laboratory facilities (47.3%). Rearrangement or redeployment of the workforce was reported in 53.3% and 34.1% of laboratories, respectively. The majority of the respondents reported a significant reduction (>10%) in caseload associated with both gynecological (82.0%) and nongynecological specimens (78.4%). Most laboratories reported no significant change in the malignancy rates of both gynecological (67.7%) and nongynecological specimens (58.7%) compared with the same period in 2019. CONCLUSIONS: The results of the survey demonstrated that the COVID-19 pandemic resulted in a significant reduction in the number of cytology specimens examined along with the need to implement new biosafety protocols. These findings underscore the need for the worldwide standardization of biosafety protocols and cytology practice.


Assuntos
COVID-19/prevenção & controle , Controle de Doenças Transmissíveis/normas , Transmissão de Doença Infecciosa do Paciente para o Profissional/prevenção & controle , Laboratórios Hospitalares/organização & administração , Patologia Clínica/organização & administração , Ásia , COVID-19/epidemiologia , COVID-19/transmissão , COVID-19/virologia , Controle de Doenças Transmissíveis/instrumentação , Mão de Obra em Saúde/organização & administração , Mão de Obra em Saúde/normas , Mão de Obra em Saúde/estatística & dados numéricos , Humanos , Laboratórios Hospitalares/normas , Laboratórios Hospitalares/estatística & dados numéricos , Estados do Pacífico , Pandemias/prevenção & controle , Patologia Clínica/normas , Patologia Clínica/estatística & dados numéricos , Equipamento de Proteção Individual/normas , SARS-CoV-2/patogenicidade , Inquéritos e Questionários/estatística & dados numéricos , Carga de Trabalho/estatística & dados numéricos
10.
PLoS One ; 15(4): e0231411, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32271831

RESUMO

BACKGROUND: Venous thromboembolism (VTE) associated with surgery can cause serious comorbidities or death and imposes a substantial economic burden to society. The study examined VTE cases after surgery to determined how this condition imposed an economic burden on patients based on the national health insurance reimbursement database. Methods: This retrospective analysis adopted the public payer's perspective. The direct medical cost was estimated using data from the national claims database of Vietnam from Jan 1, 2017 to Sep 31, 2018. Adult patients who underwent surgeries were recruited for the study. Patients with a diagnostic code of up to 90 days after surgery were considered VTE cases with the outcome measure being the surgery-related costs within 90 days. RESULTS: The 90-day cost of VTE patients was found to be US$2,939. The rate of readmission increased by 5.4 times, the rate of outpatient visits increased by 1.8 times and total costs over 90 days in patients with VTE undergoing surgery increased by 2.2 times. Estimation using propensity score matching method showed that an increase of US$1,019 in the 90-day cost of VTE patients. CONCLUSION: The VTE-related costs can be used to assess the potential economic benefit and cost-savings from prevention efforts.


Assuntos
Efeitos Psicossociais da Doença , Tromboembolia Venosa/patologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Estudos de Casos e Controles , Bases de Dados Factuais , Feminino , Humanos , Revisão da Utilização de Seguros , Masculino , Pessoa de Meia-Idade , Pontuação de Propensão , Estudos Retrospectivos , Procedimentos Cirúrgicos Operatórios/efeitos adversos , Tromboembolia Venosa/economia , Tromboembolia Venosa/etiologia , Vietnã , Adulto Jovem
11.
Prog Community Health Partnersh ; 12(3): 341-352, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30581177

RESUMO

BACKGROUND: The Institute of Medicine (IOM)'s Subcommittee on Standardized Collection of Race/Ethnicity Data for Healthcare Quality Improvement recommends standardized collection of the existing Office of Management and Budget race and Hispanic ethnicity categories as well as locally relevant categories of disaggregated ethnicity and languages. The lack of category standardization hinders achieving health outcomes for many populations most at risk for increasing morbidity and mortality. In Oregon state, the need to collect data from disaggregated ethnic populations had been identified but no timeline had been established for implementation. METHODS: This article describes a model for community organizing for policy change with 48 local organizations that consists of advocacy organizations, communities of color, and organizations with legislative expertise, for the Oregon House Bill 2134, which aimed to disaggregate ethnicity and language data. CONCLUSIONS: Details of the process experience with partner organizations who were at the table and key legislative strategies facilitating this policy change are discussed.


Assuntos
Pesquisa Participativa Baseada na Comunidade , Coleta de Dados/normas , Política de Saúde/legislação & jurisprudência , Disparidades em Assistência à Saúde/estatística & dados numéricos , Idioma , Modelos Organizacionais , Grupos Raciais/estatística & dados numéricos , Populações Vulneráveis , Humanos , Oregon
12.
Asian Pac Isl Nurs J ; 3(4): 154-159, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-31037263

RESUMO

Caring for America's aging population is a complex humanitarian issue. The number of older adults is expected to increase to 98.5 million by 2060 with a 295% growth in foreign-born older adults, including Asian immigrants. Most older adults will have one or more chronic conditions and 95% of healthcare costs will be attributed to caring for these conditions. Among Asian Americans, common chronic conditions include respiratory disease, cancer, cardiovascular disease, and pain. The National Institutes of Health, Institute on Aging, and National Science Foundation call for innovative technologies to be developed by multidisciplinary teams to address these concerns. Asian community leaders at Asian Health & Service Center and community members in Oregon identified the use of health-assistive technologies as a priority for potentially reducing stress and improving quality of life for both older adults and their caregivers. The purpose of this article is to introduce nurses and healthcare workers, advocating for the interests of Asian/Pacific Island community members, to the innovative health-assistive smart home. The health-assistive smart home uses artificial intelligence to identify and predict health events. Inclusion of minority persons' data in the development of artificial intelligence has been generally overlooked. This may result in continued health inequities and is incompatible with the goals of global health. Integration of minority voices while exploring the efficacious use of the health-assistive smart home is of significant value to minority populations. Asian immigrant older adults engaging in smart home research and development will enhance the cultural and technical safety of future devices. Asian families may be particularly interested in smart homes for extending independence because they place an emphasis on collective culture and family-based care. Community engagement of stakeholders and steadfast leadership are needed so that future technologies used in healthcare delivery are both technically and culturally sound. A community-engaged research approach promotes community empowerment that is responsive to community identified priorities and is a good fit for studying adoption of smart home monitoring for health-assistance.

13.
J Chem Phys ; 138(18): 185101, 2013 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-23676073

RESUMO

We have developed the lattice model for describing polypeptide chains in the presence of crowders. The influence of crowding confinement on the fibrillation kinetics of polypeptide chains is studied using this model. We observed the non-trivial behavior of the fibril formation time τfib that it decreases with the concentration of crowders if crowder sizes are large enough, but the growth is observed for crowders of small sizes. This allows us to explain the recent experimental observation on the dual effect of crowding particles on fibril growth of proteins that for a fixed crowder concentration the fibrillation kinetics is fastest at intermediate values of total surface of crowders. It becomes slow at either small or large coverages of cosolutes. It is shown that due to competition between the energetics and entropic effects, the dependence of τfib on the size of confined space is described by a parabolic function.


Assuntos
Simulação de Dinâmica Molecular , Peptídeos/química , Cinética , Método de Monte Carlo
14.
J Chem Phys ; 137(9): 095101, 2012 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-22957596

RESUMO

A new method for determining the size of critical nucleus of fibril formation of polypeptide chains is proposed. Based on the hypothesis that the fibril grows by addition of a nascent peptide to the preformed template, the nucleus size N(c) is defined as the number of forming template peptides above which the time to add a new monomer becomes independent of the template size. Using lattice models one can show that our method and the standard method which is based on calculation of the free energy, provide the same result for N(c).


Assuntos
Modelos Moleculares , Peptídeos/química , Multimerização Proteica , Método de Monte Carlo , Dobramento de Proteína , Estrutura Secundária de Proteína , Temperatura , Termodinâmica
15.
IEEE Trans Image Process ; 17(7): 1121-8, 2008 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-18586620

RESUMO

This paper presents an edge-directed image interpolation algorithm. In the proposed algorithm, the edge directions are implicitly estimated with a statistical-based approach. In opposite to explicit edge directions, the local edge directions are indicated by length-16 weighting vectors. Implicitly, the weighting vectors are used to formulate geometric regularity (GR) constraint (smoothness along edges and sharpness across edges) and the GR constraint is imposed on the interpolated image through the Markov random field (MRF) model. Furthermore, under the maximum a posteriori-MRF framework, the desired interpolated image corresponds to the minimal energy state of a 2-D random field given the low-resolution image. Simulated annealing methods are used to search for the minimal energy state from the state space. To lower the computational complexity of MRF, a single-pass implementation is designed, which performs nearly as well as the iterative optimization. Simulation results show that the proposed MRF model-based edge-directed interpolation method produces edges with strong geometric regularity. Compared to traditional methods and other edge-directed interpolation methods, the proposed method improves the subjective quality of the interpolated edges while maintaining a high PSNR level.


Assuntos
Algoritmos , Inteligência Artificial , Aumento da Imagem/métodos , Interpretação de Imagem Assistida por Computador/métodos , Reconhecimento Automatizado de Padrão/métodos , Simulação por Computador , Cadeias de Markov , Modelos Estatísticos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
16.
IEEE Trans Image Process ; 16(11): 2633-48, 2007 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-17990741

RESUMO

In this paper, a motion-compensated de-interlacing algorithm using the Markov random field (MRF) model is proposed. The de-interlacing problem is formulated as a maximum a posteriori (MAP) MRF problem. The MAP solution is the one that minimizes an energy function, which imposes discontinuity-adaptive smoothness (DAS) spatial constraint on the de-interlaced frame. The edge direction information, which is used to formulate the DAS constraint, is implicitly indicated by weight vectors (weights for 16 digitized directions). Generally, large weights are assigned to along-edge directions and relatively small weights are assigned to across-edge directions. As a local statistical-based method, the proposed weighting method should be more robust than traditional edge-directed interpolation methods in deciding local edge directions. The proposed algorithm is implemented by an iterative optimization process, which guarantees convergence. However, a global optimal solution is not guaranteed due to computational complexity concern. Simulation results compare the proposed algorithm to other motion compensated de-interlacing algorithms. Significant improvements of de-interlaced edges are observed.


Assuntos
Algoritmos , Artefatos , Aumento da Imagem/métodos , Interpretação de Imagem Assistida por Computador/métodos , Armazenamento e Recuperação da Informação/métodos , Gravação em Vídeo/métodos , Simulação por Computador , Interpretação Estatística de Dados , Cadeias de Markov , Modelos Estatísticos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade
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