Organic light-emitting devices fabricated utilizing core/shell CdSe/ZnS quantum dots embedded in a polyvinylcarbazole

Electrical and the optical properties of organic light-emitting devices (OLEDs) fabricated utilizing core/shell CdSe/ZnS quantum dots (QDs) embedded in a polyvinylcarbazole (PVK) layer were investigated. An abrupt increase of the current density above an applied voltage of 12 V for OLEDs consisting of Al/LiF/4,7-diphenyl-1,10-phenanthroline/bis-(2-methyl-8-quinolinolate)-4-(phenylphenolato) aluminium/[CdSe/ZnS QDs embedded in PVK]/poly(3,4-ethylenedioxythiophene) and poly(styrenesulfonate)/ITO/glass substrate was attributed to the existence of the QDs. Photoluminescence spectra showed that the peaks at 390 and 636 nm corresponding to the PVK layer and the CdSe/ZnS QDs were observed. While the electroluminescence (EL) peak of the OLEDs at low voltage range was related to the PVK layer, the EL peak of the OLEDs above 12 V was dominantly attributed to the CdSe/ZnS QDs. The Commission Internationale de l’Eclairage (CIE) chromaticity coordinates of the OLEDs at high voltages were (0.581, 0.380) indicative of a red color. When the holes existing in the PVK layer above 12 V were tunneled into the CdSe/ZnS QDs, the holes occupied by the CdSe/ZnS QDs combined with the electrons in the PVK layer to emit a red color related to the CdSe/ZnS QDs.     

Optimal Switching In Structured Treatment Interruption For Hiv Therapy

This paper proposes ‘optimal switching control during structured treatment interruption,’ which switches RTI and PI to reduce medication and establish long‐term immune response against HIV. The proposed method is compared with ‘optimized STI’ through numerical simulation. The proposed method results in a more rapid increase of CTLp, and thus total drug intake and the therapy period are reduced. HIV treatment simulation results are analyzed in terms of controllability. Due to the effect of PI, ‘optimal switching control during STI’ can achieve greater controllability more quickly than ‘optimized STI.’     

Chromosomal localization of mouse Cenpa gene

Using a previously isolated mouse centromere protein A (Cenpa) probe, we have localized the gene to the proximal region of mouse Chromosome 5, between the known Il6 and Yes1 loci near [Adra2C-D5H4S43-Hdh]. Comparison of this localization with that of human CENPA, which maps to chromosome 2, is consistent with the presence of a new region of conserved synteny between the two species.     

Static strength of collar plate reinforced CHS X-joints loaded by in-plane bending

This paper presents the collar plate reinforcement scheme to strengthen a Circular Hollow Section (CHS) X-joint, applicable for a fabricated joint which is subsequently found to be under-strength. The parametric numerical study on the static strength of collar plate reinforced X-joints loaded by in-plane bending is complementary to the study on doubler plate reinforced joints as reported in the companion paper. The load transferring mechanisms and failure modes of these reinforced joints are investigated and compared. From the range of geometric parameters investigated, the collar plate reinforcement is found to be more effective than its doubler plate counterpart to improve the static strength of the joints. Based on the numerical results, strength equations are established to estimate the static strength of collar plate reinforced X-joints.     

Epidemiology of falls among the elderly community dwellers in Singapore

AIM: Falling is a serious medical problem for elderly persons. This study was done to look at prevalence and risk factors for falls in community dwelling elderly in Singapore. METHOD: A random sample of 3,000 persons aged 60 years and above was chosen from a database based on the 1990 population census. Letters were sent out to 2,582 subjects who had local and complete addresses. In the letter, they were informed about the purpose of the survey, and invited to participate in a questionnaire and clinical health screening at an appointed date at a polyclinic. Participants were reminded the day before their appointment by telephone, and a new appointment could be given at the subject's convenience. RESULTS: We found a prevalence rate of falls of 17.2%. Two-thirds of these had single falls, while one-third had recurrent falls, defined as having more than one fall within the previous one year. The following factors were found to be significantly associated with increase falling in the elderly: age > or = 75 years (O.R. = 1.82, 95% C.I. 0.95-3.50), female sex (O.R. = 2.5, 95% C.I. 1.40-4.48), Malay race (O.R. = 2.66, 95% C.I. 1.21-5.86), poor vision (O.R. = 1.7, 95% C.I. 0.99-2.90), Barthel's score of less than 20 (O.R. = 1.76, 95% C.I. 0.94-3.28), those taking 2 or more drugs daily (O.R. = 2.1, 95% C.I. 1.22-3.72) and the presence of hypertension (O.R. = 1.78, 95% C.I. 1.06-3.01). Fall rate is also twice as high in women as in men. At the same time, we found that women in the group we studied also tend to exercise less than the men. Fallers also had significantly more mobility and activities of daily living (ADL) disabilities (reflected by a lower Barthel's score) and this is consistent with other results. The only factor that reduced the risk of falling was regular exercise (O.R. = 1.64, 95% C.I. 0.93-2.93). CONCLUSION: In our study, we found differences between the group with single and recurrent falls. In the group with single falls, the fall tend to occur outdoors (O.R. = 2.97, 95% C.I. 1.03-8.60) and during the day (O.R. = 3.47, 95% C.I. 1.20-10.0), tend to be accidental (O.R. = 3.16, 95% C.I. 1.05-9.50) and tend to seek medical attention (O.R. = 3.68, 95% C.I. 1.23-11.0). Overall, 32 persons (46.4%) seek medical treatment after their falls, and of these, 65.6% were women. Risk factors for falls should be screened for all elderly.     

Correction

The online version of the original article can be found at     

On the Execution of Large Batch Programs in Unreliable Computing Systems

The execution of long-running batch programs imposes severe reliability constraints on a computing system since the occurrence of a failure during its execution is more likely and that once occurred, a failure would destroy all the processing perfonned thus far. This paper studies the execution delay and machine resources consumed in supporting the running of large batch programs in a computing environment interrupted by failures. The effect of checkpoints and their optimal insertion are also considered. The results are applicable to arbitrary law of failure.     

The effect of environmental pH on the failure strain of anodic films formed on the aluminum alloy 2024

The ultimate tensile strain of anodic films formed on 2024-T4 aluminum was evaluated as a function of pH in environments of 10⁻³M and 1·0M KNO₃, using resistive and capactive techniques. In the resistive technique, ultimate tensile strain was defined as the strain at which a discontinuous increase in anodic current was observed; in the capacitive technique, film failure was marked by a discontinuity in the slope of the capacitance versus strain curve. The ultimate tensile strain was seen to be significantly greater at the zero-point-of charge of the oxide (pH 8) than at higher or lower pH; in the capacitive measurements the ultimate tensile strain had an average value of 0·97 at pH 8 and 0·87 for measurements made at pH values of 4, 7 and 9. Dielectric behavior of the anodic films was seen to be different only in degree from that of films formed on pure aluminum. Changes in capacitance associated only with exposure were measured and taken into account. Capacitance behavior with strain was modeled by two linear regions; the first was attributed to elastic deformation of the film and the second, after failure, to the growth of regions of metal covered only with a thin, spontaneously-formed oxide.