2,141 research outputs found
The random walk behaviour of Malaysian stock market : Evidence from individual stocks
This study re-examines the price behaviour of 77 individual stocks listed on Bursa Malaysia in light of the random walk hypothesis. With a new statistical tool, namely the Brock-Dechert-Scheinkman( BDS) test, it is possible to detect a more complex form of dependencies in series of financial returns that often appear completely random to standard statistical tests, such as serial correlation tests, runs test, variance ratio test and unit root tests. Our econometric results reveal that the market in general as proxied by the KLCI and all the 77 individual stocks do not follow a random walk process. This conclusion holds even when the sample period is broken down into two sub-periods with the exception of five stocks- IOICorp, KLK, MUllnd, Pos Hldgs and Tchong. The price behaviour of these five stocks in the sub-periods before and during the crisis provides empirical support to our conjecture that the Asian financial crisis in 1997 adversely affected the market's ability to price stocks efficiently, thus preventing stock prices from following a random walk process
Analysis of a Fragmenting Sunspot using Hinode Observations
We employ high resolution filtergrams and polarimetric measurements from
Hinode to follow the evolution of a sunspot for eight days starting on June 28,
2007. The imaging data were corrected for intensity gradients, projection
effects, and instrumental stray light prior to the analysis. The observations
show the formation of a light bridge at one corner of the sunspot by a slow
intrusion of neighbouring penumbral filaments. This divided the umbra into two
individual umbral cores. During the light bridge formation, there was a steep
increase in its intensity from 0.28 to 0.7 I_QS in nearly 4 hr, followed by a
gradual increase to quiet Sun (QS) values in 13 hr. This increase in intensity
was accompanied by a large reduction in the field strength from 1800 G to 300
G. The smaller umbral core gradually broke away from the parent sunspot nearly
2 days after the formation of the light bridge rendering the parent spot
without a penumbra at the location of fragmentation. The penumbra in the
fragment disappeared first within 34 hr, followed by the fragment whose area
decayed exponentially with a time constant of 22 hr. The depleted penumbra in
the parent sunspot regenerated when the inclination of the magnetic field at
the penumbra-QS boundary became within 40 deg. from being completely horizontal
and this occurred near the end of the fragment's lifetime. After the
disappearance of the fragment, another light bridge formed in the parent which
had similar properties as the fragmenting one, but did not divide the sunspot.
The significant weakening in field strength in the light bridge along with the
presence of granulation is suggestive of strong convection in the sunspot which
might have triggered the expulsion and fragmentation of the smaller spot.
Although the presence of QS photospheric conditions in sunspot umbrae could be
a necessary condition for fragmentation, it is not a sufficient one.Comment: Accepted for publication in ApJ; 15 pages, 15 figures, 1 tabl
Polymeric Nanoparticles Amenable to Simultaneous Installation of Exterior Targeting and Interior Therapeutic Proteins
Effective delivery of therapeutic proteins is a formidable challenge. Herein, using a unique polymer family with a wide-ranging set of cationic and hydrophobic features, we developed a novel nanoparticle (NP) platform capable of installing protein ligands on the particle surface and simultaneously carrying therapeutic proteins inside by a self-assembly procedure. The loaded therapeutic proteins (e.g., insulin) within the NPs exhibited sustained and tunable release, while the surface-coated protein ligands (e.g., transferrin) were demonstrated to alter the NP cellular behaviors. In vivo results revealed that the transferrin-coated NPs can effectively be transported across the intestinal epithelium for oral insulin delivery, leading to a notable hypoglycemic response.National Institutes of Health (U.S.) (Grants EB015419, R00CA160350, and CA151884)Prostate Cancer Foundation (Challenge Award)National Research Foundation of Korea (Grant K1A1A2048701)David H. Koch Institute for Integrative Cancer Research at MIT. Prostate Cancer Foundation Program in Cancer NanotherapeuticsNational Natural Science Foundation (China) (Grant 81173010
Does the revised cardiac risk index predict cardiac complications following elective lung resection?
Background:
Revised Cardiac Risk Index (RCRI) score and Thoracic Revised Cardiac Risk Index (ThRCRI) score were developed to predict the risks of postoperative major cardiac complications in generic surgical population and thoracic surgery respectively. This study aims to determine the accuracy of these scores in predicting the risk of developing cardiac complications including atrial arrhythmias after lung resection surgery in adults.
Methods:
We studied 703 patients undergoing lung resection surgery in a tertiary thoracic surgery centre. Observed outcome measures of postoperative cardiac morbidity and mortality were compared against those predicted by risk.
Results:
Postoperative major cardiac complications and supraventricular arrhythmias occurred in 4.8% of patients. Both index scores had poor discriminative ability for predicting postoperative cardiac complications with an area under receiver operating characteristic (ROC) curve of 0.59 (95% CI 0.51-0.67) for the RCRI score and 0.57 (95% CI 0.49-0.66) for the ThRCRI score.
Conclusions:
In our cohort, RCRI and ThRCRI scores failed to accurately predict the risk of cardiac complications in patients undergoing elective resection of lung cancer. The British Thoracic Society (BTS) recommendation to seek a cardiology referral for all asymptomatic pre-operative lung resection patients with > 3 RCRI risk factors is thus unlikely to be of clinical benefit
Preparedness for practice of newly qualified dental professionals in Australia - educator, employer, and consumer perspectives
BACKGROUND: Limited data regarding the perspectives of other observers (i.e. those who educate, employ or receive care from) of new graduates’ preparedness to practice is available. The present study aimed to explore perceptions of different observers regarding the preparedness to practice and work readiness of newly qualified dental professionals. This broader range of perspectives is crucial to inform the development of educational programs, including continuing professional development, for newly qualified dental professionals, by clarifying the skills, knowledge and behaviours expected by the dental profession and wider public. RESULTS: Nineteen individual qualitative interviews were undertaken. Interview participants included clinical demonstrators (n = 9; 2 Oral Health Therapists; 5 Dentists; and 2 Prosthetists), dental course convenors (n = 4), representatives of large employers (n = 2), and consumers (n = 4). According to this diverse group of respondents, dental students receive adequate theoretical and evidence-based information in their formal learning and teaching activities, which prepares them for practice as dental professionals. There were no specific clinical areas or procedures where preparedness was highlighted as a major concern. Notwithstanding this, specific graduate skills which would benefit from further training and consolidation were identified, including areas where higher levels of experience would be beneficial. Nonetheless, respondents indicated that new graduates were aware of their limitations and had developed self-discipline and ethics that would allow them to identify conditions/situations where they would not have the experience or expertise to provide care safely. CONCLUSIONS: From an observer perspective, dental students appeared to have gained adequate theoretical and evidence-based information in their formal learning and teaching activities to prepared them to commence practicing safely as dental professionals. Areas were identified in which new graduates were underprepared and when transitional support may be required
Preparedness for practice of newly qualified dental practitioners in the Australian context:an exploratory study
BACKGROUND: The current study explored the perspectives of preparedness for dental practice from a range of relevant stakeholders (i.e., educators, employers, final-year students, graduates, practitioners, and professional associations) using an anonymous online survey in which participants described either their preparedness for practice, or the preparedness of graduates they have encountered, across six domains. RESULTS: A total of 120 participants completed the survey. Participants were from several Australian states and territories; regional, rural, and urban locations; and working in the public and private sector. Students and new graduates generally felt prepared for activities in all the identified domains. Stakeholders reported consistently that the knowledge of dental profession graduates was at the required level to enter practice in Australia in a safe way. Activities involving the knowledge of clinical entrepreneurship and financial solvency were the dimensions where students and graduates felt least prepared (e.g., explaining fees, negotiating finances). In the domains involving clinical and technical competencies, students and new graduates self-assessed as less prepared around managing dental trauma and medical emergencies. On the other hand, activities around social and community orientation, and to a lesser extent professional attitudes and ethical judgements, were the dimensions where students and graduates felt the most prepared. CONCLUSIONS: Present findings indicate that there appear to be good standards of preparedness for practice for graduate dental professionals. This exploratory study provides insights into the nature of preparedness for Australian dental professionals and provides a basis for targeting education and professional development to address areas of need
North American extreme precipitation events and related large-scale meteorological patterns: a review of statistical methods, dynamics, modeling, and trends
This paper surveys the current state of knowledge regarding large-scale meteorological patterns (LSMPs) associated with short-duration (less than 1 week) extreme precipitation events over North America. In contrast to teleconnections, which are typically defined based on the characteristic spatial variations of a meteorological field or on the remote circulation response to a known forcing, LSMPs are defined relative to the occurrence of a specific phenomenon-here, extreme precipitation-and with an emphasis on the synoptic scales that have a primary influence in individual events, have medium-range weather predictability, and are well-resolved in both weather and climate models. For the LSMP relationship with extreme precipitation, we consider the previous literature with respect to definitions and data, dynamical mechanisms, model representation, and climate change trends. There is considerable uncertainty in identifying extremes based on existing observational precipitation data and some limitations in analyzing the associated LSMPs in reanalysis data. Many different definitions of "extreme" are in use, making it difficult to directly compare different studies. Dynamically, several types of meteorological systems-extratropical cyclones, tropical cyclones, mesoscale convective systems, and mesohighs-and several mechanisms-fronts, atmospheric rivers, and orographic ascent-have been shown to be important aspects of extreme precipitation LSMPs. The extreme precipitation is often realized through mesoscale processes organized, enhanced, or triggered by the LSMP. Understanding of model representation, trends, and projections for LSMPs is at an early stage, although some promising analysis techniques have been identified and the LSMP perspective is useful for evaluating the model dynamics associated with extremes.11Ysciescopu
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