Portfolio value-at-risk estimation for spot chartering decisions under changing trade patterns: A copula approach.

Evolving geopolitical relationships between countries (especially between China and the United States) in recent years have highlighted dynamically changing trade patterns across the globe, all of which elevate risk and uncertainty for transport service providers. In order to mitigate risks, shipowners and operators must be able to estimate risks appropriately; one potentially promising method of doing so is through the value-at-risk (VaR) method. VaR describes the worst loss a portfolio is likely to sustain, which will not be exceeded over a target time horizon at a given level of confidence. This article proposes a copula-based GARCH model to estimate the joint multivariate distribution, which is a key component in VaR estimation. We show that the copula model can capture the VaR more successfully, as compared with the traditional method of calculation. As an empirical study, the expected portfolio VaR is examined when a shipowner chooses among Panamax soybean trading routes under a condition of reduced trade volumes between the United States and China due to the ongoing trade turmoil. This study serves as one of the very few papers in the literature on shipping portfolio VaR analysis. The results have significant implications for shipowners regarding fleet repositioning, decision making, and risk management.

Outcomes of cataract operations in extreme high axial myopia.

PURPOSE: To analyse the outcomes of phacoemulsification in extreme axial myopia METHODS: Consecutive cases of phacoemulsification in eyes with axial length ≥ 30.0 mm from January 1, 2010 to Dec 31, 2013 in a tertiary referral eye hospital were retrospectively reviewed. A single intraocular lens (IOL) type was used for all cases. Main outcome measures included perioperative complications and refractive outcome. RESULTS: Two hundred and twenty-one eyes were identified. Intraoperatively, two eyes (0.9 %) had unstable capsular bag and three (1.4 %) had posterior capsular rupture. At a mean follow-up duration was 27.4 ± 14.6 months, three eyes (1.5 % of 198 eyes with no history of retinal detachment or macular hole) developed retinal detachment. There was an overall hyperopic shift with a mean biometry error of 0.45 ± 1.21 D in all eyes. The mean absolute biometry prediction error was 0.98 ± 0.83 D in all eyes, 1.11 ± 0.86 D and 0.85 ± 0.82 D in eyes receiving negative- and positive-power IOL, respectively (p = 0.042). A total of 61.2 % of eyes had refractive outcome within ± 1.0 D of target spherical equivalent. Regression analysis showed low IOL power as an independent predictor for greater postoperative absolute biometry error (p = 0.014). CONCLUSIONS: We showed no increase in perioperative complications in eyes with extreme high axial myopia. In eyes with long axial length, implantation of IOL with lower power was associated with more hyperopic shift, which was more pronounced with negative-power IOL.

Human Ocular Dirofilariasis in Hong Kong.

PURPOSE: Human dirofilariasis is a helminthic infestation caused by filarial nematodes of the genus Dirofilaria. We report two cases of subconjunctival dirofilariasis in adult Chinese patients. CASE REPORTS: Case 1: A 57-year-old woman presented to us with 1-day history of left eye redness and migratory foreign body sensation. Physical examination showed a temporal subconjunctival motile mass in her left eye. Immediate surgical exploration showed a live nonpigmented roundworm measuring 120 mm in length with morphology compatible with Dirofilaria. It was later identified to be Dirofilaria repens by sequence analysis. Case 2: A 69-year-old woman presented with left eye redness and foreign body sensation for 2 weeks. She was treated elsewhere initially with topical antibiotics without any improvement. On slitlamp examination, a mobile subconjunctival mass was noted. Immediate surgical removal was performed under local anesthesia, revealing a live 50-mm-long worm. It was identified as Dirofilaria hongkongensis. Both patients had normal systemic workup results and remained symptom-free after surgical removal of the nematode. Clinical findings, diagnosis, pathogenesis, and management are discussed. CONCLUSIONS: Ophthalmic dirofilariasis is a rare condition. Clinicians should be aware of this disease entity so that prompt diagnosis and treatment could be offered to the patients.

Personal spiritual values and quality of life: evidence from Chinese college students.

Values are guiding principles in our life. While some studies found spiritual values to be "healthier," Sagiv and Schwartz (Eur J Soc Psychol 30:177-198, 2000) showed that people holding non-spiritual values were higher on affective well-being. We examined the predictive power of these two types of values with a longitudinal data set collected from Chinese students mainly in Hong Kong. Structural equation modeling revealed that spiritual values (as well as family income) positively predicted quality of life a year later. Non-spiritual, self-enhancement values, did not show any association. Results suggest that developing spiritual values may promote well-being through enabling individuals to find meaning and purpose in life.

Risk assessment of ammonia bunkering operations: Perspectives on different release scales.

Ammonia is an alternative marine fuel to reduce greenhouse gas emissions. Conducting studies on ammonia bunkering risk is essential as ammonia is toxic and corrosive to humans and the environment. This study aims to assess the ammonia bunkering operational risk from the perspectives of small, medium and large release scales. Scaling releases from small to medium results in more changes in cloud footprints at lower gas concentrations. Conversely, transitioning from medium to large releases causes more changes in cloud footprints at higher gas concentrations and lethality footprints with higher values. Moreover, this study performs a sensitivity analysis on ammonia bunkering supply, release, and meteorological factors. Wind speed is the most significant factor in small and medium releases, while hose diameter is the most significant factor in large releases. Under the given inputs, a 50% change in wind speed can have up to 100% change in the 1100 ppm maximum cloud footprint for small releases and a 663% change for medium releases. Similarly, a 50% change in hose diameter can result in a 1689% change in the 1100 ppm maximum cloud footprint for large releases. The research provides valuable insights into analysing ammonia bunkering operational risk considering different risk assessment criteria.

Accidental release of ammonia during ammonia bunkering: Dispersion behaviour under the influence of operational and weather conditions in Singapore.

Ammonia is identified as a potential marine fuel, and ammonia bunkering will take place in major bunkering ports, including Singapore. Due to its toxic nature, any accidental release of ammonia into the environment during bunkering operation has a risk of spreading rapidly and causing injury to the personnel in the vicinity and damage to the marine ecosystem. This safety study simulates how key operational parameters affect ammonia dispersion and the consequences. The results show that bunkering ammonia stored in fully-refrigerated tanks as an atmospheric pressure saturated liquid is the safest, and the severity of the consequence increases significantly with a release height of more than 5 m. A vertical release of ammonia results in the most severe consequence and shall be avoided at all times. Reducing the release duration and transfer flow rate can reduce the severity significantly. Based on the scenario used in this study, ammonia cloud disperses over a longer distance over water due to the high vaporisation rate driven by the large amount of heat generated from the dissolution of ammonia in seawater. The dispersion of ammonia over the sea spreads over a larger area during the day than at night.

Laparoscopic management of gastrointestinal stromal tumours: review at a Canadian centre.

BACKGROUND: Laparoscopic wedge resection has been widely accepted for small benign gastric tumours. Large gastrointestinal stromal tumours (GISTs), however, can be difficult to manipulate laparoscopically and are at risk for capsule disruption, which can then result in peritoneal seeding. Some authors have suggested that large GISTs (> 8 cm) are best approached using an open technique. However, there has been no consensus as to what the cut-off size should be. We conducted one of the largest Canadian series to date to assess outcomes and follow-up of the laparoscopic management of GISTs. METHODS: All patients with gastric GISTs presenting to Vancouver General Hospital and University of British Columbia Hospital between 2000 and 2008 were reviewed. Most lesions were resected using a wedge technique with closure of the stomach facilitated by an endoscopic linear stapling device. RESULTS: In all, 23 patients presented with GISTs; 19 patients underwent laparoscopic resection and, of these, 15 had a purely laparoscopic operation and 4 had a hand-assisted laparoscopic resection. Mean tumour size was 3.2 cm, with the largest tumour measuring 6.8 cm. There were no episodes of tumour rupture or spillage and no major intraoperative complications. All margins were negative. Mean follow-up was 13.3 (range 1-78) months. There was no evidence of recurrence or metastasis. CONCLUSION: The laparoscopic management of gastric GISTs is safe and effective with short hospital stays and good results over a mean follow-up of 13.3 months. We believe that it should be the preferred technique offered to patients.

Accelerated corneal collagen cross-linking in progressive keratoconus: Five-year results and predictors of visual and topographic outcomes.

Purpose: To analyze the 5-year results of accelerated corneal collagen crosslinking (CXL) for progressive keratoconus and identify preoperative characteristics predictive of visual and topographic outcomes. Methods: A prospective interventional case series. Nineteen eyes of 19 patients receiving accelerated CXL with settings of 18 mW/cm2 for 5 min were included. Clinical and topographic parameters were assessed. Linear regression and logistic regression were used to compare the R2 and odds ratio (OR), respectively, between baseline characteristics and postoperative outcomes. Results: Corrected distance visual acuity (CDVA) remained stable from 0.28 ± 0.21 to 0.25 ± 0.18 logMAR (P = 0.486). The mean cylindrical refraction was stable (P = 0.119). The maximal keratometry (Kmax) decreased from 61.99 ± 10.37 to 59.25 ± 7.75 D (P < 0.001), flattening in the flattest and steepest meridians and mean keratometry were also observed (P ≤ 0.040). The mean anterior elevation at the apex reduced from 21.42 ± 16.69 to 18.53 ± 12.74 µm (P = 0.013) and changes in posterior elevation were non-significant (P = 0.629). Preoperative Kmax best predicted the postoperative change in Kmax (R2 = 0.55, P < 0.001) compared to the other baseline characteristics (P ≤ 0.028), whereas preoperative CDVA was the only significant predictor of postoperative change in CDVA (R2 = 0.41, P = 0.003). Accelerated CXL is less likely to fail in eyes with a steeper preoperative Kmax (OR = 0.74, P = 0.040) or greater posterior elevation at the apex (OR = 0.91, P = 0.042). Conclusion: Kmax significantly decreased following accelerated CXL. Eyes with worse preoperative CDVA and higher Kmax were more likely to have an improvement in visual acuity and corneal flattening.

Fixation stability and deviation in optical coherence tomography angiography using soft contact lens correction in myopes.

To compare fixation deviation and stability with soft contact lens correction and device built-in auto-focus system during optical coherence tomography angiography (OCTA). This observational study measured OCTA metrics first with contact lens correction, followed by removal of contact lenses, using the device auto-focus system at a University Optometry Clinic, Hong Kong. All participants were habitual soft contact lens wearers with either low or high myopia. OCTA measurements were obtained using a spectral domain OCTA. Fixation deviation was distance (in pixels) of the fovea to the center of the OCTA measurement grid. Fixation stability was test-retest repeatability (TRR) and coefficient of variation (CV) of fixation deviation from three consecutive OCTA measurements. OCTA metrics included vessel length density (VD), perfusion density (PD), and foveal avascular zone (FAZ) area. Averaged OCTA metrics were calculated from three measurements and compared between the two correction methods. The mean ± SD spherical equivalent of 74 eyes from 74 myopes measured was - 1.94D ± 0.75D in low myopes (n = 37) and - 7.97D ± 1.31D in high myopes (n = 37). When corrected with contact lenses, visual acuities of high myopes (median [IQR], - 0.06 [0.08] logMAR) and low myopes (- 0.02 ± 0.08 logMAR) were similar (P = 0.060), and with similar fixation deviation (5.0 ± 2.2 pixels vs 5.3 [3.6] pixels; P = 0.689). High myopes had poorer fixation stability than low myopes (TRR: 10.2 pixels vs 7.5 pixels; CV: 65% vs 54%, respectively). The worst fixation stability occurred when high myopes were corrected using the auto-focus system (TRR: 12.5 pixels, CV: 72%). The difference in VD and PD was within 1 mm-1 and 1%, respectively. The FAZ area was similar. Difference in OCTA metrics was small in each refractive group (< 1 mm-1 in VD, and < 2% in PD). High myopes had more stable fixation when corrected when wearing contact lenses. Subjects with good contact lens corrected visual acuity should wear their contact lenses during OCTA measurements.

A longitudinal investigation of the bidirectional relationship of sleep quality with emotional stability and social cynicism in a large community sample.

OBJECTIVE: Dispositional characteristics like emotional stability and social cynicism have been consistently associated with negative affect, which is a known predictor and outcome of poor sleep quality. This study hypothesized a bidirectional relationship of sleep quality with emotional stability and social cynicism over a five-year period. METHODS: Participants were 7,181 Chinese people, who completed two waves of online surveys from a larger panel study. Questionnaires on Big Five personality traits, social cynicism, and sleep quality were administered twice at a five-year interval. RESULTS: Cross-lagged analysis revealed a significant bidirectional relationship between emotional stability and sleep quality over five years as hypothesized. However, there was no association between sleep quality and social cynicism in either direction. CONCLUSION: Our study provides consistent evidence of a bidirectional relationship between sleep quality and emotional stability in a five-year time-frame among a younger population (mean age = 24.86). Given the critical role of emotional stability in various areas of functioning, the findings highlight the importance of sleep health education in young adults, who are going through a critical period of personality development.

Chinese medicine: its role and application in the institutionalised older people.

AIMS: The aim of the study was to explore the need for and application of Chinese medicine services and factors which impact on the accessibility of Chinese medicine among the institutionalised older people. BACKGROUND: Although complementary and alternative medicine is widely used by older Chinese both in Hong Kong and elsewhere, little is known about its use by the institutionalised older people. This study breaks new ground by exploring how Chinese medicine, the most popular form of complementary and alternative medicine used by older people, is used and accessed by the institutionalised older people in Hong Kong. DESIGN: Qualitative method. METHODS: Semi-structured interviews were conducted in 2007 with 18 older individuals aged between 63-93 and living in three long-term care facilities in Hong Kong. RESULTS: Three main categories emerged from the data: (1) the role of Chinese medicine in the care of the aged; (2) barriers to the use of Chinese medicine in residences; and (3) factors facilitating the accessibility of Chinese medicine services in residences. Most of the older individuals interviewed claimed that Chinese medicine played a crucial role in their self-health management. The availability of Chinese medicine depended crucially on the support of the health care system, individual institutions and nursing staff. CONCLUSIONS: The value of Chinese medicine in the care of the institutionalised older people was highlighted. Chinese medicine as a complement to western medicine was perceived as an important component of self-health management. Attitudes towards the use of Chinese medicine in nursing homes therefore need to be reviewed and developed further in accordance with the health strategy policy. RELEVANCE TO CLINICAL PRACTICE: This research focuses on the role of complementary and alternative medicine in health care for the institutionalised older people. It provides health practitioners, researchers and policy makers with an additional perspective in the provision of quality client-centred care for older people living in long-term care.

Sleep and optimism: A longitudinal study of bidirectional causal relationship and its mediating and moderating variables in a Chinese student sample.

While both sleep and optimism have been found to be predictive of well-being, few studies have examined their relationship with each other. Neither do we know much about the mediators and moderators of the relationship. This study investigated (1) the causal relationship between sleep quality and optimism in a college student sample, (2) the role of symptoms of depression, anxiety, and stress as mediators, and (3) how circadian preference might moderate the relationship. Internet survey data were collected from 1,684 full-time university students (67.6% female, mean age = 20.9 years, SD = 2.66) at three time-points, spanning about 19 months. Measures included the Attributional Style Questionnaire, the Pittsburgh Sleep Quality Index, the Composite Scale of Morningness, and the Depression Anxiety Stress Scale-21. Moderate correlations were found among sleep quality, depressive mood, stress symptoms, anxiety symptoms, and optimism. Cross-lagged analyses showed a bidirectional effect between optimism and sleep quality. Moreover, path analyses demonstrated that anxiety and stress symptoms partially mediated the influence of optimism on sleep quality, while depressive mood partially mediated the influence of sleep quality on optimism. In support of our hypothesis, sleep quality affects mood symptoms and optimism differently for different circadian preferences. Poor sleep results in depressive mood and thus pessimism in non-morning persons only. In contrast, the aggregated (direct and indirect) effects of optimism on sleep quality were invariant of circadian preference. Taken together, people who are pessimistic generally have more anxious mood and stress symptoms, which adversely affect sleep while morningness seems to have a specific protective effect countering the potential damage poor sleep has on optimism. In conclusion, optimism and sleep quality were both cause and effect of each other. Depressive mood partially explained the effect of sleep quality on optimism, whereas anxiety and stress symptoms were mechanisms bridging optimism to sleep quality. This was the first study examining the complex relationships among sleep quality, optimism, and mood symptoms altogether longitudinally in a student sample. Implications on prevention and intervention for sleep problems and mood disorders are discussed.

Bidirectional relationship between sleep and optimism with depressive mood as a mediator: A longitudinal study of Chinese working adults.

OBJECTIVE: Sleep and optimism are important psycho-biological and personality constructs, respectively. However, very little work has examined the causal relationship between them, and none has examined the potential mechanisms operating in the relationship. This study aimed to understand whether sleep quality was a cause or an effect of optimism, and whether depressive mood could explain the relationship. METHOD: Internet survey data were collected from 987 Chinese working adults (63.4% female, 92.4% full-time workers, 27.0% married, 90.2% Hong Kong residents, mean age=32.59 at three time-points, spanning about 19 months). Measures included a Chinese attributional style questionnaire, the Pittsburgh Sleep Quality Index, and the Depression Anxiety Stress Scale. RESULTS: Cross-sectional analyses revealed moderate correlations among sleep quality, depressive mood, and optimism. Cross-lagged analyses showed a bidirectional causality between optimism and sleep. Path analysis demonstrated that depressive mood fully mediated the influence of optimism on sleep quality, and it partially mediated the influence of sleep quality on optimism. CONCLUSION: Optimism improves sleep. Poor sleep makes a pessimist. The effects of sleep quality on optimism could not be fully explained by depressive mood, highlighting the unique role of sleep on optimism. Understanding the mechanisms of the feedback loop of sleep quality, mood, and optimism may provide insights for clinical interventions for individuals presented with mood-related problems.

Comparison of outcomes of primary anterior chamber versus secondary scleral-fixated intraocular lens implantation in complicated cataract surgeries.

PURPOSE: To compare the outcome of primary anterior chamber vs secondary scleral-fixated intraocular lens (IOL) implantation in complicated cataract surgeries. DESIGN: Retrospective, comparative study. METHODS: A consecutive series of complicated cataract surgeries with primary anterior chamber (ACIOL) or secondary scleral-fixated IOL implantation from January 1, 2004 to December 31, 2009 was analyzed. Main outcome measures included the postoperative best-corrected visual acuity (BCVA) and postoperative complications. RESULTS: There were 89 eyes in the primary ACIOL group and 74 eyes in the secondary scleral-fixated IOL group. The mean follow-up duration was 64.1 ± 36.7 months. The mean postoperative logarithm of minimal angle of resolution (logMAR) BCVA at 1 year was 0.32 ± 0.54 and 0.34 ± 0.21 in the primary ACIOL group and the secondary scleral-fixated IOL group, respectively (P = .734). The mean latest logMAR BCVA was 0.68 ± 0.54 and 0.61 ± 0.47 in the primary ACIOL group and the secondary scleral-fixated IOL group, respectively (P = .336). The primary ACIOL group had more early postoperative complications (P < .001). No difference in late postoperative complications was observed between the 2 groups (P = .100). Regression analysis showed that primary ACIOL and secondary scleral-fixated IOL implantation had similar latest postoperative logMAR BCVA (P = .927), while the presence of late complications was associated with a worse final visual outcome (P = .000). CONCLUSIONS: This study shows that there are no long-term differences in the visual outcomes and complication profiles after primary ACIOL or secondary scleral-fixated IOL implantation in a complicated cataract operation when capsular support is inadequate.

Intraocular pressure profiles during femtosecond laser-assisted cataract surgery.

PURPOSE: To document the intraocular pressure (IOP) profiles during femtosecond laser-assisted cataract surgery. SETTING: Refractive cataract surgery center. DESIGN: Prospective case series. METHODS: Intraocular pressure was measured using a handheld portable applanation tonometer (Tono-Pen Avia) during femtosecond laser-assisted cataract surgery using the Victus platform. RESULTS: Forty-one eyes of 35 patients were recruited. The mean age of the patients was 70.5 years ± 8.2 (SD) (range 51 to 85 years). The mean IOP before, during, and after suction was 17.2 ± 3.2 mm Hg (range 10 to 23 mm Hg), 42.1 ± 10.8 mm Hg (range 20 to 55 mm Hg), and 13.8 ± 3.4 mm Hg (range 9 to 25 mm Hg), respectively. The mean difference between IOP before and during suction was 25.0 ± 11.3 mm Hg (range 5 to 43 mm Hg) (P<.01, Wilcoxon signed-rank test). The mean difference between IOP during and after suction was -28.7 ± 10.8 mm Hg (range -45 to -10 mm Hg) (P<.01, Wilcoxon signed-rank test). The mean suction duration was 216 ± 15 seconds (range 180 to 245 seconds). CONCLUSIONS: The increase in IOP during the suction phase of femtosecond laser-assisted cataract surgery was statistically significant compared with the baseline IOP. Caution should be taken in patients with ocular conditions that are vulnerable to IOP fluctuation. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Understanding barriers to cataract surgery among older persons in rural China through focus groups.

PURPOSE: To utilize focus groups (FGs) to identify barriers to cataract surgery specific to older persons in rural Guangdong, China. METHODS: Three focus groups in separate locations were carried out for persons aged 60 years and above with best-corrected vision <= 6/18 due to cataract, either accepting or refusing surgery. Participants also ranked responses to questions about acceptance of surgery among the elderly. FG transcripts were coded independently by two investigators using qualitative data management software. RESULTS: Twenty participants had a mean age of 72.7 ± 6.1 years, 14 (70.0%) were women and 17 (85.0%) were blind (best-corrected vision <= 6/60) in at least one eye. Cost was ranked by two of three groups as the main barrier to surgery, and all groups listed reducing cost as the best strategy to increase surgical uptake. Many respondents planned to use China's New Cooperative Medical Scheme (NCMS) health insurance to pay for surgery. Participants showed poor understanding of cataract, but ranked educational interventions low as methods of increasing uptake. Though opinions of local service quality were poor, respondents did not see quality as an important barrier to accepting service. Participants frequently depended on family members to pay for surgery. CONCLUSIONS: Contrary to some previous reports, cost may be an important barrier to cataract surgery in rural China, which NCMS may help to alleviate. Educational interventions to increase knowledge about cataract are needed, but may face skepticism among patients. Strategies to promote cataract surgery should target the entire family.