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1.
J Adv Nurs ; 2024 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-38586889

RESUMO

AIM: To examine the main effects and interaction effects of outcome expectations (e.g., anticipated satisfactory salary and benefits), nurse identity (a sense of membership in the nursing profession), and information-access efficiency of the electronic medical record system (how the system enables nurses to quickly retrieve the needed information) on nurses' retention. DESIGN: This study uses a cross-sectional survey and adopts proportionate random sampling to recruit a representative sample of nurses of a medical centre in Taiwan. METHODS: This study successfully obtained completed questionnaires from 430 nurses during December 2021 to January 2022. Data are analysed by using hierarchical regressions. RESULTS: Positive outcome expectations and identification as a member in the nursing profession are associated with retention. Information-access efficiency strengthens the link between outcome expectations and retention, while nurse identity weakens this link. CONCLUSION: Outcome expectations can help retain nurses, particularly those who perceive high levels of information-access efficiency and possess weak nurse identity. That is, outcome expectations have a complementary role with nurse identity in retaining nurses. IMPLICATIONS FOR THE PROFESSION: Nurse managers should devise means to build positive outcome expectations for nurses. In addition, either strengthening nurses' identification with the nursing profession or improving the information-access efficiency of the electronic medical system may also help retain nurses. IMPACT: This study examined how to transform outcome expectation to nurse retention, offering nurse managers to devise new means to retain nurses. REPORTING METHOD: STROBE statement was chosen as EQUATOR checklist. PATIENT OR PUBLIC CONTRIBUTION: No patient or public contribution.

2.
Int Nurs Rev ; 2024 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-38243697

RESUMO

AIM: To investigate whether education, tenure, being an advanced practice nurse, skill level, and time pressure impact perceptions of "having a place" and, further, turnover intentions. BACKGROUND: Nursing shortages persist worldwide. Nurses' turnover intentions are negatively related to their perceptions of "having a place" (i.e., the feeling that the nursing workplace is their territory). However, the sources of nurses' perceptions of the perception of "having a place" remain unknown. METHODS: Our research employed a cross-sectional and correlational design. This research was conducted at a large-scale hospital in northern Taiwan from December 2021 to January 2022. We used personnel data pertaining to 430 nurses as well as scales for time pressure, "having a place" and turnover intentions to assess nurses' intention to leave their place of employment. The inclusion criteria focused on full-time nurses who worked for the hospital under investigation. Most of our participants were women. The STROBE statement was used as the EQUATOR checklist (supplemental file). RESULTS: "Having a place" was positively related to educational level, tenure, and skill level, while being an advanced practice nurse was negatively associated with perceptions of "having a place," which in turn were negatively related to turnover intention among nurses. CONCLUSION: Our study is the first to examine the antecedents of nurses' perceptions of "having a place," which include education, tenure, and skill level. IMPLICATIONS FOR NURSING POLICY: Nursing policymakers could encourage nurses to pursue higher degrees and update their nursing skills while instilling perceptions of "having a place" in nurses with a brief tenure and advanced practice nurses.

3.
J Adv Nurs ; 79(12): 4756-4766, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-37334431

RESUMO

AIMS: To examine how nurses' self-efficacy impacts professional engagement (professional opportunities exploration and workplace improvement participation), nurses' turnover intention and further on actual turnover. BACKGROUND: The problem of nursing shortage has become a common global issue. Nurses' self-efficacy could reduce nurses' turnover intention. However, whether professional engagement could connect nurses' self-efficacy and their actual turnover remains unknown. DESIGN: This study adopts a three-wave follow-up design. METHODS: This study uses proportionate random sampling to survey nurses in a large medical centre in Taiwan. Totally, 417 participants were enrolled from December 2021 to January 2022 (first wave) and followed up from February 2022 to March 2022 (second wave). The data of nurses' actual turnover (or not) were traced in May 2022 (third wave). STROBE statement was chosen as the EQUATOR checklist. RESULTS: Self-efficacy was positively linked to outcome expectation, which is positively linked to professional opportunities exploration. Self-efficacy was positively linked to career interest and workplace improvement participation. Professional engagement was negatively linked to nurses' intention to leave the target hospital, which was positively linked to actual turnover. CONCLUSION: This study uniquely finds that professional engagement is the key to the mechanism underlying the influence of nurse' self-efficacy on their actual turnover. IMPACT: Our findings impact nursing management that professional engagement is as well important as nurses' self-efficacy, with an aim to maintain the professional nursing workforce. PATIENT OR PUBLIC CONTRIBUTION: Nurses complete the questionnaires, return them to the investigators and permit investigators to check their personnel data.


Assuntos
Enfermeiras e Enfermeiros , Recursos Humanos de Enfermagem Hospitalar , Humanos , Autoeficácia , Estudos Transversais , Intenção , Local de Trabalho , Reorganização de Recursos Humanos , Inquéritos e Questionários , Satisfação no Emprego
4.
Artigo em Inglês | MEDLINE | ID: mdl-36674115

RESUMO

Objective: The purpose of this paper is to investigate whether playing exergames can enhance quality of life among young adults and it examines the potential moderators. Methods: A 12-week randomized controlled trial was conducted. Quality of life was measured using the short-form 36-item version (SF-36) scale. All the participants were between 20 and 24 years old in Taiwan. Participants in the intervention group (n = 55) were asked to play exergames for 12 weeks, three times a week and 30 minutes at a time, while participants in the control group (n = 62) did not play exergames. The changes in the scores on quality of life between the beginning and the end of the 12-week trial were calculated. Independent t-tests were used to analyze the differences. Results: The intervention group participants experienced an enhanced quality of life in terms of physical functioning, role-physical (role limitations due to physical health), general health, and social functioning. Moreover, the intervention group participants who were not enthusiastic about exercisers experienced an enhanced quality of life in physical functioning, role-physical, and general health. The intervention group participants who attempted to control their weight experienced enhanced general health, vitality, and mental health. Conclusion: Playing exergaming could contribute to users' quality of life in terms of both physical and mental health.


Assuntos
Jogos Eletrônicos de Movimento , Jogos de Vídeo , Humanos , Adulto Jovem , Adulto , Qualidade de Vida , Jogos de Vídeo/psicologia , Exame Físico , Taiwan
5.
J Med Internet Res ; 25: e37731, 2023 01 09.
Artigo em Inglês | MEDLINE | ID: mdl-36622738

RESUMO

BACKGROUND: Robots are introduced into health care contexts to assist health care professionals. However, we do not know how the benefits and maintenance of robots influence nurse-robot engagement. OBJECTIVE: This study aimed to examine how the benefits and maintenance of robots and nurses' personal innovativeness impact nurses' attitudes to robots and nurse-robot engagement. METHODS: Our study adopted a 2-wave follow-up design. We surveyed 358 registered nurses in operating rooms in a large-scale medical center in Taiwan. The first-wave data were collected from October to November 2019. The second-wave data were collected from December 2019 to February 2020. In total, 344 nurses participated in the first wave. We used telephone to follow up with them and successfully followed-up with 331 nurses in the second wave. RESULTS: Robot benefits are positively related to nurse-robot engagement (ß=.13, P<.05), while robot maintenance requirements are negatively related to nurse-robot engagement (ß=-.15, P<.05). Our structural model fit the data acceptably (comparative fit index=0.96, incremental fit index=0.96, nonnormed fit index=0.95, root mean square error of approximation=0.075). CONCLUSIONS: Our study is the first to examine how the benefits and maintenance requirements of assistive robots influence nurses' engagement with them. We found that the impact of robot benefits on nurse-robot engagement outweighs that of robot maintenance requirements. Hence, robot makers should consider emphasizing design and communication of robot benefits in the health care context.


Assuntos
Robótica , Humanos , Estudos Transversais , Hospitais , Inquéritos e Questionários , Pessoal de Saúde
6.
Artigo em Inglês | MEDLINE | ID: mdl-36141423

RESUMO

To achieve the goals of carbon peak and carbon neutrality, the low-carbon transformation (LCT) of high-carbon firms is inevitable. We construct game models of a supply chain with different dominant types under a mixed carbon policy that embraces carbon cap-and-trade and carbon tax. Solving each dominant model, we derive the effective area and optimal threshold of the mixed carbon policy to guide LCT. We find that the selling price, market demand, and profit of the supply chain system are equal in different dominant models due to the mixed carbon policy, but when a company dominates the supply chain, its profit is higher than when it is a subordinate. In addition, the high-carbon manufacturers (HCM) will pursue LCT only when the sum of the carbon tax rates and carbon trading prices is within a certain threshold, and the subordinate HCM are more likely to be driven to pursue LCT. Therefore, the government should adopt a differentiated hybrid carbon policy, setting a high (low) carbon tax rate for the HCM in a dominant (subordinate) position.


Assuntos
Carbono , Impostos , Comércio , Governo , Políticas
7.
Ann Oper Res ; : 1-24, 2022 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-35194284

RESUMO

Vaccination is a well-known method to protect the public against an epidemic outbreak, e.g., COVID-19. To this end, the government of a country or region would strive to achieve its target of vaccination coverage. Limited by the total vaccine capacity of public hospitals, the government may need to cooperate with private hospitals or clinics for more vaccination. Exploring in this paper government coordination of public and private resources for vaccination, we model a vaccine system consisting of a public hospital, a profit-maximizing private clinic, and self-interested individuals, under three scenarios: (1) without information sharing (concerning vaccine inventory and vaccine price), (2) with information sharing and subsidy, and (3) with information sharing and allocation. We find that, under scenario (1), the vaccine demand is fully satisfied by the public hospital and the private clinic cannot make any profit. Under scenario (2), the private clinic is willing to enter the vaccine market with a positive profit-maximizing vaccination coverage. Under scenario (3), the socially optimal vaccination coverage may be lower than that under scenario (1). Moreover, we conduct a sensitivity analysis to generate practical implications of the research findings for vaccination policy-making. Our results provide both theoretical and managerial insights on vaccine supply decision, government intervention, and vaccination coverage.

8.
Appl Soft Comput ; 113: 107946, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34646110

RESUMO

The COVID-19 epidemic has had a great adverse impact on the world, having taken a heavy toll, killing hundreds of thousands of people. In order to help the world better combat COVID-19 and reduce its death toll, this study focuses on the COVID-19 mortality. First, using the multiple stepwise regression analysis method, the factors from eight aspects (economy, society, climate etc.) that may affect the mortality rates of COVID-19 in various countries is examined. In addition, a two-layer nested heterogeneous ensemble learning-based prediction method that combines linear regression (LR), support vector machine (SVM), and extreme learning machine (ELM) is developed to predict the development trends of COVID-19 mortality in various countries. Based on data from 79 countries, the experiment proves that age structure (proportion of the population over 70 years old) and medical resources (number of beds) are the main factors affecting the mortality of COVID-19 in each country. In addition, it is found that the number of nucleic acid tests and climatic factors are correlated with COVID-19 mortality. At the same time, when predicting COVID-19 mortality, the proposed heterogeneous ensemble learning-based prediction method shows better prediction ability than state-of-the-art machine learning methods such as LR, SVM, ELM, random forest (RF), long short-term memory (LSTM) etc.

9.
Ann Tour Res ; 87: 103117, 2021 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33518847

RESUMO

This paper is to produce different scenarios in forecasts for international tourism demand, in light of the COVID-19 pandemic. By implementing two distinct methodologies (the Long Short Term Memory neural network and the Generalized Additive Model), based on recent crises, we are able to calculate the expected drop in the international tourist arrivals for the next 12 months. We use a rolling-window testing strategy to calculate accuracy metrics and show that even though all models have comparable accuracy, the forecasts produced vary significantly according to the training data set, a finding that should be alarming to researchers. Our results indicate that the drop in tourist arrivals can range between 30.8% and 76.3% and will persist at least until June 2021.

10.
Games Health J ; 8(3): 220-226, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30418041

RESUMO

Objective: Exergames are popular technology applications that encourage individuals to engage in exercise and create positive moods for players. However, little is known as to whether playing exergames makes players perceive to be more energetic and relaxed and whether enthusiasm about doing exercise moderates such perceptions. To answer these questions, we use the Flow Theory and the Self-Determination Theory to develop the hypotheses. Methods: We conducted a randomized controlled trial, which randomly assigned 337 participants to an intervention group and a control group. We asked the participants in the intervention group to play exergames for 2 weeks. We measured enthusiasm about doing exercise by asking the participants to evaluate themselves as having enthusiasm on doing exercise or not. We measured participants' perceptions of happiness, perceived energy (the perception of sufficient physical and mental resources), and relaxation before and after the 2-week exergame playing, generating scores to represent their changes. Results: We found that playing exergames induces positive changes in happiness, perceived energy, and relaxation. Such changes were significant for participants who are enthusiastic about doing exercise, but not for those who are unenthusiastic about doing exercise. Conclusion: This study was the first using the Flow Theory and the Self-Determination Theory to examine the impact of playing exergames on players' perceptions and to identify the moderator role of enthusiasm about doing exercise. These positive impacts of exergames can be used in rehabilitation settings in encouraging positive attitudes and behaviors toward exercise.


Assuntos
Exercício Físico/psicologia , Participação do Paciente/psicologia , Percepção , Jogos de Vídeo/psicologia , Adulto , Análise de Variância , Feminino , Felicidade , Humanos , Masculino , Participação do Paciente/métodos , Psicometria/instrumentação , Psicometria/métodos , Taiwan , Jogos de Vídeo/normas
11.
Health Policy ; 122(8): 892-899, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-29759682

RESUMO

There is limited empirical evidence of the nature of any relationship between health spending and health outcomes in Australia. We address this by estimating the elasticity of health outcomes with respect to public healthcare spending using an instrumental variable (IV) approach to account for endogeneity of healthcare spending to health outcomes. Results suggest that, based on the conditional mean, a 1% increase in public health spending was associated with a 2.2% (p < 0.05) reduction in the number of standardised Years of Life Lost (YLL). Sensitivity analyses and robustness checks supported this conclusion. Further exploration using IV quantile regression indicated that marginal returns on public health spending were significantly greater for areas with poorer health outcomes compared to areas with better health outcomes. On average, marginal increases in public health spending reduce YLL, but areas with poorer health outcomes have the greatest potential to benefit from the same marginal increase in public health spending compared to areas with better health outcomes. Understanding the relationship between health spending and outcomes and how this differs according to baseline health outcomes can help meet dual policy objectives to improve the productivity of the healthcare system and reduce inequity.


Assuntos
Financiamento Governamental/estatística & dados numéricos , Gastos em Saúde/estatística & dados numéricos , Mortalidade , Avaliação de Resultados em Cuidados de Saúde/estatística & dados numéricos , Austrália , Custos e Análise de Custo/métodos , Custos e Análise de Custo/estatística & dados numéricos , Humanos , Expectativa de Vida , Modelos Estatísticos
12.
Artigo em Chinês | MEDLINE | ID: mdl-29798149

RESUMO

Objective:To investigate the protective effect of optimized target delineation in intensity modulated radiation therapy(IMRT) on swallowing function in patients with different TNM staging of nasopharyngeal carcinoma.Method:Fifty patients with nasopharyngeal carcinoma were enrolled in this study. They were randomly divided into 25 cases of experimental group and 25 cases of control group by random number table and received IMRT treatment. Patients in control group only received routine delineation of target areas, the patients in experimental group were given the delineation of the relevant parts of the swallowing on the basis of the control group.And then, the degree of dysphagia, xerostomia, weight loss, and quality of life were assessed in the two groups of patients during and after IMRT.Result:There was no significant change in the degree of dysphagia in stage Ⅱ patients during radiotherapy, but the degree of dysphagia in stage Ⅲ and Ⅳ patients increased with the increase of radiotherapy time. After the end of radiotherapy, there was no significant change in the degree of dysphagia in the control group of patients. Compared with the 0th week after the end of radiotherapy, the stage Ⅱ patients in experimental group showed significant improvement in week 12(P<0.05), while the stage Ⅲ and Ⅳ patients showed significant improvement in week 24 after radiotherapy(P<0.05). The degree of xerostomia of two groups of patients continued to increase with varying degrees during and after IMRT(P<0.05 or P<0.01). The weight of the two groups of patients during radiotherapy continued to decrease with the increase of radiotherapy time,and gradually recovered after the end of radiotherapy.And in the experimental group, the weight loss was significantly lower in week 12 and week 24 than in the control group (P<0.05). During radiotherapy, the quality of life scores of the two groups became lower and lower with the increase of radiotherapy time compared with the 0th week of radiotherapy. After the end of radiotherapy, the quality of life began to gradually improve, and in week 24 after the end of radiotherapy, the quality of life of the experimental group of patients was significantly higher than that of the control group (P<0.05).Conclusion:During radiotherapy of patients with nasopharyngeal carcinoma, the structural organs associated with swallowing function are given individualized target delineation can reduce the occurring of dysphagia due to radiotherapy and improve the quality of life of patients after radiotherapy.


Assuntos
Deglutição , Carcinoma Nasofaríngeo/radioterapia , Neoplasias Nasofaríngeas/radioterapia , Radioterapia de Intensidade Modulada , Humanos , Estadiamento de Neoplasias , Qualidade de Vida , Dosagem Radioterapêutica
13.
Hong Kong Med J ; 24(2): 119-127, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29633715

RESUMO

INTRODUCTION: Under the current opt-in system, the deceased organ donation rate remains low in Hong Kong. An opt-out system and an opt-in system combined with organ allocation priority (ie, priority to donors as transplant recipients) have been proposed to encourage willingness among the general population towards deceased organ donation. This study aimed to compare willingness, and its determinants, across these three legislative systems. METHODS: A random telephone survey of Hong Kong permanent residents aged ≥18 years was conducted between August and October 2016 using an anonymous questionnaire. Willingness towards deceased organ donation was compared between the legislative systems with McNemar's test. Determinants of willingness were tested by logistic regression. RESULTS: The proportion of those willing to consider deceased organ donation under the current opt-in system would significantly increase after combining it with allocation priority (64.5% vs 73.4%; P=0.018). "Fairness or reciprocity" was the major reported reason underlying the increase. In contrast, willingness would decrease after introducing the opt-out system (60.1%), although not significantly (P=0.336). The reduction might be attributable to a "belief of being forced to donate". Under the allocation priority system, reduced willingness to donate was associated with advanced age, lower educational attainment, and lower monthly household income. Under the opt-out system, reduced willingness was associated with being married, having a lower household income, and distrust of local government. CONCLUSIONS: An opt-in system with allocation priority could induce willingness to donate, whereas an opt-out system may reduce willingness. The findings have implications for policy-making and promotion of organ donation.


Assuntos
Obtenção de Tecidos e Órgãos/legislação & jurisprudência , Adolescente , Adulto , Estudos Transversais , Feminino , Hong Kong , Humanos , Masculino , Formulação de Políticas , Adulto Jovem
14.
Nat Commun ; 6: 6620, 2015 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-25782977

RESUMO

Current methods of chemical vapour deposition (CVD) of graphene on copper are complicated by multiple processing steps and by high temperatures required in both preparing the copper and inducing subsequent film growth. Here we demonstrate a plasma-enhanced CVD chemistry that enables the entire process to take place in a single step, at reduced temperatures (<420 °C), and in a matter of minutes. Growth on copper foils is found to nucleate from arrays of well-aligned domains, and the ensuing films possess sub-nanometre smoothness, excellent crystalline quality, low strain, few defects and room-temperature electrical mobility up to (6.0±1.0) × 10(4) cm(2) V(-1) s(-1), better than that of large, single-crystalline graphene derived from thermal CVD growth. These results indicate that elevated temperatures and crystalline substrates are not necessary for synthesizing high-quality graphene.

15.
Genet Mol Res ; 13(4): 9543-57, 2014 Nov 12.
Artigo em Inglês | MEDLINE | ID: mdl-25501164

RESUMO

Phalaenopsis orchids have been regenerated by inducing protocorm-like bodies (PLBs) from etiolated leaf sections. However, the physiological and molecular mechanisms of secondary PLB development and subsequent proliferation have not been explored. Bisectionally cutting primary PLBs resulted in more secondary PLBs at 5 weeks, suggesting an embryogenic stem cell property imposed by wounding of primary PLB tissues. The ethylene precursors ethephon and 1-aminocyclopropanecarboxylic acid and the ethylene perception inhibitor silver nitrate increased PLB formation, while aminoethoxyvinylglycine decreased PLB formation. Ethylene content in wounded PLB explants increased over culture time in media containing ethylene precursors or inhibitors. mRNA levels of PhACS2, PhACS3, and PhACO were increased by ethephon and decreased by ethylene inhibitors. Expression of genes in the ethylene signaling pathway was enhanced following ethylene-precursor treatment and was mitigated by ethylene inhibitors during PLB proliferation. Transcription of PhETR and PhEIN3, as well as PhERS, PhCTR, and PhGTP, was significantly increased 12 h after ethylene treatment. Ethylene and physical wounding stimulated secondary PLB formation in Phalaenopsis, probably through ethylene biosynthesis and signal transduction.


Assuntos
Etilenos/farmacologia , Orchidaceae/citologia , Orchidaceae/embriologia , Regeneração/efeitos dos fármacos , Sementes/citologia , Proliferação de Células/efeitos dos fármacos , Etilenos/biossíntese , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Orchidaceae/efeitos dos fármacos , Orchidaceae/genética , Regeneração/genética , Sementes/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética , Células-Tronco/citologia , Células-Tronco/efeitos dos fármacos
16.
Cancer Gene Ther ; 20(5): 276-81, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23598434

RESUMO

Extracellular activation of hydrophilic glucuronide prodrugs by ß-glucuronidase (ßG) was examined to increase the therapeutic efficacy of bacteria-directed enzyme prodrug therapy (BDEPT). ßG was expressed on the surface of Escherichia coli by fusion to either the bacterial autotransporter protein Adhesin (membrane ßG (mßG)/AIDA) or the lipoprotein (lpp) outermembrane protein A (mßG/lpp). Both mßG/AIDA and mßG/lpp were expressed on the bacterial surface, but only mßG/AIDA displayed enzymatic activity. The rate of substrate hydrolysis by mßG/AIDA-BL21cells was 2.6-fold greater than by pßG-BL21 cells, which express periplasmic ßG. Human colon cancer HCT116 cells that were incubated with mßG/AIDA-BL21 bacteria were sensitive to a glucuronide prodrug (p-hydroxy aniline mustard ß-D-glucuronide, HAMG) with an half maximal inhibitory concentration (IC50) value of 226.53±45.4 µM, similar to the IC50 value of the active drug (p-hydroxy aniline mustard, pHAM; 70.6±6.75 µM), indicating that mßG/AIDA on BL21 bacteria could rapidly and efficiently convert HAMG to an active anticancer agent. These results suggest that surface display of functional ßG on bacteria can enhance the hydrolysis of glucuronide prodrugs and may increase the effectiveness of BDEPT.


Assuntos
Escherichia coli/enzimologia , Glucuronatos/farmacocinética , Glucuronidase/metabolismo , Glucuronídeos/farmacocinética , Nitrofenóis/farmacocinética , Pró-Fármacos/farmacocinética , Proteínas de Transporte/farmacocinética , Escherichia coli/genética , Glucuronidase/biossíntese , Glucuronidase/genética , Células HCT116 , Humanos , Proteínas Recombinantes , Células Tumorais Cultivadas
17.
J Phys Chem A ; 117(32): 6984-90, 2013 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-23374094

RESUMO

Cluster ions of H7(+)/D7(+) and H9(+)/D9(+) produced in a supersonic molecular beam with a pulsed discharge source are mass selected and studied with infrared laser photodissociation spectroscopy. Photodissociation occurs by the loss of H2 (D2) from each cluster, producing resonances in the 2000-4500 cm(-1) region. Vibrational patterns indicate that these ions consist of an H3(+) (D3(+)) core ion solvated by H2 (D2) molecules. There is no evidence for the shared proton structure seen previously for H5(+). The H3(+) ion core vibrational bands are weakened and broadened significantly, presumably by enhanced rates of intramolecular vibrational relaxation. Computational studies at the DFT/B3LYP or MP2 levels of theory (including scaling) are adequate to reproduce qualitative details of the vibrational spectra, but neither provides quantitative agreement with vibrational frequencies.

18.
J Phys Chem A ; 116(37): 9287-94, 2012 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-22946445

RESUMO

Pulsed discharges containing methanol or ethanol produce ions having the nominal formula [C,H(3),O](+), i.e. m/z = 31. Similar ions resulting from electron impact ionization in mass spectrometers are long recognized to have either the CH(2)OH(+) protonated formaldehyde or CH(3)O(+) methoxy cation structures. The H(2)OCH(+) oxonio-methylene structure has also been suggested by computational chemistry. To investigate these structures, ions are expanded in a supersonic beam, mass-selected in a time-of-flight spectrometer, and studied with infrared laser photodissociation spectroscopy. Sharp bands in the O-H and C-H stretching and fingerprint regions are compared to computational predictions for the three isomeric structures and their vibrational spectra. Protonated formaldehyde is the most abundant isomer, but methoxy is also formed with significant abundance. The branching ratio of these two ion species varies with precursors and formation conditions.

19.
J Phys Chem A ; 116(26): 7065-73, 2012 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-22676649

RESUMO

Protonated benzene cluster ions, H(C(6)H(6))(2)(+) and H(C(6)H(6))(3)(+), are produced in a pulsed electrical discharge source coupled to a supersonic expansion. Mass-selected complexes are investigated with infrared photodissociation spectroscopy in the 1000-3200 cm(-1) region using the method of argon tagging. The IR spectra of H(C(6)H(6))(2)(+)-Ar and H(C(6)H(6))(3)(+)-Ar contain broad bands in the high frequency region resulting from CH-π hydrogen bonds. Sharp peaks are observed in the fingerprint region arising from the ring modes of both the C(6)H(7)(+) and C(6)H(6) moieties. M06-2X calculations have been performed to investigate the structures and vibrational spectra of energetically low-lying configurations of these complexes. H(C(6)H(6))(2)(+) is predicted to have three nearly isoenergetic conformers: the parallel displaced (PD), T-shaped (TS), and canted (C) structures [Jaeger, H. M.; Schaefer, H. F.; Hohenstein, E. G.; Sherrill, C. D. Comput. Theor. Chem. 2011, 973, 47-52]. A comparison of the experimental dimer spectrum with those predicted for the three isomers suggests an average structure between the TS and PD conformers, which is consistent with the low energy barrier predicted to separate these two structures. No evidence is found for the C dimer even though it lies only 1.2 kcal/mol above the PD dimer. Although the trimer is also computed to have many low lying isomers, the IR spectrum limits the possible species present.


Assuntos
Benzeno/química , Dimerização , Prótons , Vibração , Modelos Moleculares , Conformação Molecular , Espectrofotometria Infravermelho
20.
Accid Anal Prev ; 49: 457-69, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22578904

RESUMO

Recent reports on work safety in container shipping operations highlight high frequencies of human failures. In this study, we empirically examine the effects of seafarers' perceptions of national culture on the occurrence of human failures affecting work safety in shipping operations. We develop a model adopting Hofstede's national culture construct, which comprises five dimensions, namely power distance, collectivism/individualism, uncertainty avoidance, masculinity/femininity, and Confucian dynamism. We then formulate research hypotheses from theory and test the hypotheses using survey data collected from 608 seafarers who work on global container carriers. Using a point scale for evaluating seafarers' perception of the five national culture dimensions, we find that Filipino seafarers score highest on collectivism, whereas Chinese and Taiwanese seafarers score highest on Confucian dynamism, followed by collectivism, masculinity, power distance, and uncertainty avoidance. The results also indicate that Taiwanese seafarers have a propensity for uncertainty avoidance and masculinity, whereas Filipino seafarers lean more towards power distance, masculinity, and collectivism, which are consistent with the findings of Hofstede and Bond (1988). The results suggest that there will be fewer human failures in container shipping operations when power distance is low, and collectivism and uncertainty avoidance are high. Specifically, this study finds that Confucian dynamism plays an important moderating role as it affects the strength of associations between some national culture dimensions and human failures. Finally, we discuss our findings' contribution to the development of national culture theory and their managerial implications for reducing the occurrence of human failures in shipping operations.


Assuntos
Acidentes de Trabalho/prevenção & controle , Confucionismo , Características Culturais , Segurança , Navios , Acidentes de Trabalho/psicologia , Adulto , China , Análise Fatorial , Humanos , Pessoa de Meia-Idade , Modelos Teóricos , Filipinas , Análise de Regressão , Valores Sociais , Inquéritos e Questionários , Taiwan
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