Engineering of impact ionization characteristics in In0.53Ga0.47As/Al0.48In0.52As superlattice avalanche photodiodes on InP substrate.

We report on engineering impact ionization characteristics of In0.53Ga0.47As/Al0.48In0.52As superlattice avalanche photodiodes (InGaAs/AlInAs SL APDs) on InP substrate to design and demonstrate an APD with low k-value. We design InGaAs/AlInAs SL APDs with three different SL periods (4 ML, 6 ML, and 8 ML) to achieve the same composition as Al0.4Ga0.07In0.53As quaternary random alloy (RA). The simulated results of an RA and the three SLs predict that the SLs have lower k-values than the RA because the electrons can readily reach their threshold energy for impact ionization while the holes experience the multiple valence minibands scattering. The shorter period of SL shows the lower k-value. To support the theoretical prediction, the designed 6 ML and 8 ML SLs are experimentally demonstrated. The 8 ML SL shows k-value of 0.22, which is lower than the k-value of the RA. The 6 ML SL exhibits even lower k-value than the 8 ML SL, indicating that the shorter period of the SL, the lower k-value as predicted. This work is a theoretical modeling and experimental demonstration of engineering avalanche characteristics in InGaAs/AlInAs SLs and would assist one to design the SLs with improved performance for various SWIR APD application.

Upregulation of the microRNA cluster at the Dlk1-Dio3 locus in lung adenocarcinoma.

Mice in which lung epithelial cells can be induced to express an oncogenic Kras(G12D) develop lung adenocarcinomas in a manner analogous to humans. A myriad of genetic changes accompany lung adenocarcinomas, many of which are poorly understood. To get a comprehensive understanding of both the transcriptional and post-transcriptional changes that accompany lung adenocarcinomas, we took an omics approach in profiling both the coding genes and the non-coding small RNAs in an induced mouse model of lung adenocarcinoma. RNAseq transcriptome analysis of Kras(G12D) tumors from F1 hybrid mice revealed features specific to tumor samples. This includes the repression of a network of GTPase-related genes (Prkg1, Gnao1 and Rgs9) in tumor samples and an enrichment of Apobec1-mediated cytosine to uridine RNA editing. Furthermore, analysis of known single-nucleotide polymorphisms revealed not only a change in expression of Cd22 but also that its expression became allele specific in tumors. The most salient finding, however, came from small RNA sequencing of the tumor samples, which revealed that a cluster of ∼53 microRNAs and mRNAs at the Dlk1-Dio3 locus on mouse chromosome 12qF1 was markedly and consistently increased in tumors. Activation of this locus occurred specifically in sorted tumor-originating cancer cells. Interestingly, the 12qF1 RNAs were repressed in cultured Kras(G12D) tumor cells but reactivated when transplanted in vivo. These microRNAs have been implicated in stem cell pleuripotency and proteins targeted by these microRNAs are involved in key pathways in cancer as well as embryogenesis. Taken together, our results strongly imply that these microRNAs represent key targets in unraveling the mechanism of lung oncogenesis.

Can comprehensive specialised end-of-life care be provided at home? Lessons from a study of an innovative consultant-led community service in the UK.

The Midhurst Macmillan Specialist Palliative Care Service (MMSPCS) is a UK, medical consultant-led, multidisciplinary team aiming to provide round-the-clock advice and care, including specialist interventions, in the home, community hospitals and care homes. Of 389 referrals in 2010/11, about 85% were for cancer, from a population of about 155 000. Using a mixed method approach, the evaluation comprised: a retrospective analysis of secondary-care use in the last year of life; financial evaluation of the MMSPCS using an Activity Based Costing approach; qualitative interviews with patients, carers, health and social care staff and MMSPCS staff and volunteers; a postal survey of General Practices; and a postal survey of bereaved caregivers using the MMSPCS. The mean cost is about 3000 GBP (3461 EUR) per patient with mean cost of interventions for cancer patients in the last year of life 1900 GBP (2192 EUR). Post-referral, overall costs to the system are similar for MMSPCS and hospice-led models; however, earlier referral avoided around 20% of total costs in the last year of life. Patients and carers reported positive experiences of support, linked to the flexible way the service worked. Seventy-one per cent of patients died at home. This model may have application elsewhere.

The views of older women towards mammographic screening: a qualitative and quantitative study.

BACKGROUND: Mammographic screening has improved breast cancer survival in the screened age group. This improved survival has not been seen in older women (>70 years) where screening uptake is low. This study explores the views, knowledge and attitudes of older women towards screening. METHODS: Women (>70 years) were interviewed about breast screening. Interview findings informed the development of a questionnaire that was sent to 1000 women (>70 years) to quantify their views regarding screening. RESULTS: Twenty-six women were interviewed and a questionnaire was designed. The questionnaire response rate was 48.3% (479 out of 992). Over half (52.9%, 241 out of 456) of the respondents were unaware that they could request a mammography by voluntary self-referral and were unaware how to arrange this. Most (81.5%, 383 out of 470) had not attended breast screening since turning 70 years. Most (75.6%, 343 out of 454) felt screening was beneficial and would attend if invited. Most (90.1%, 412 out of 457) felt screening should be offered to all women regardless of age or health. CONCLUSIONS: There is a lack of knowledge about screening in older women. The majority felt that invitation to screening should be extended to the older age group regardless of age or health. The current under-utilised system of voluntary self-referral is not supported by older women.

Seroprevalence of hepatitis C in intravenous opioid users presenting in the early phase of injecting drug use in Singapore.

INTRODUCTION: All over the world, Hepatitis C virus (HCV) accounts for an estimated 130 million chronic infections. Injection drug use has become one of the most important risk factors for HCV, and within the injection drug user population, the prevalence of HCV antibody ranges from 70 to 95 percent depending on an individual's length of use and the prevalence of infection in the community. This study was undertaken to determine the prevalence of and the risk factors for Hepatitis C antibodies in injecting drug users presenting to the Community Addictions Management Programme (CAMP) in Singapore. METHODS: Eligibility criteria for inclusion in this study were all intravenous buprenorphine users presenting to CAMP. 106 subjects, who consented to the study, completed an interviewer-administered questionnaire, and underwent a urine and blood analysis. RESULTS: The prevalence rate for HCV was 42.5 percent among the subjects included in our study. The odds of seroprevalence in those sharing needles were 5.6 times that of those who were not, and the odds of seroprevalence among those using with others (peers or partners) were 6.3 times, as compared to among those who were individual users. Racial differences were also seen, but these could be accounted for by the sharing of needles. CONCLUSION: This study provides important local data at the onset of an early buprenorphine-injecting epidemic in Singapore. This data is useful for disease prevention and healthcare planning.

X-ray imaging optimization using virtual phantoms and computerized observer modelling.

This study develops and demonstrates a realistic x-ray imaging simulator with computerized observers to maximize lesion detectability and minimize patient exposure. A software package, ViPRIS, incorporating two computational patient phantoms, has been developed for simulating x-ray radiographic images. A tomographic phantom, VIP-Man, constructed from Visible Human anatomical colour images is used to simulate the scattered portion using the ESGnrc Monte Carlo code. The primary portion of an x-ray image is simulated using the projection ray-tracing method through the Visible Human CT data set. To produce a realistic image, the software simulates quantum noise, blurring effects, lesions, detector absorption efficiency and other imaging artefacts. The primary and scattered portions of an x-ray chest image are combined to form a final image for computerized observer studies and image quality analysis. Absorbed doses in organs and tissues of the segmented VIP-Man phantom were also obtained from the Monte Carlo simulations. Approximately 25,000 simulated images and 2,500,000 data files were analysed using computerized observers. Hotelling and Laguerre-Gauss Hotelling observers are used to perform various lesion detection tasks. Several model observer tasks were used including SKE/BKE, MAFC and SKEV. The energy levels and fluence at the minimum dose required to detect a small lesion were determined with respect to lesion size, location and system parameters.

Initial experience with clozapine in Woodbridge Hospital.

OBJECTIVES: This study was performed to evaluate the efficacy and side-effect profile of the atypical neuroleptic clozapine in local Asian patients with treatment-resistant schizophrenia. METHOD: Patients were treated with 12 weeks of clozapine after undergoing a washout of all previous neuroleptics. They were assessed weekly on the Brief Psychiatric Rating Scale (BPRS), Clinical Global Impression (CGI) and the Simpson-Angus Scale for Extrapyramidal Side-Effects. RESULTS: Clinical improvement (according to criteria established a priori) at study end point was shown in 78.9% of the patients. There was no statistical difference in the incidence of the extrapyramidal side-effects at starting and end points. The mean daily dosage was 356.6 mg. The most common adverse effect was hypersalivation. CONCLUSION: Clozapine is effective and well tolerated in local patients with treatment-resistant schizophrenia.

Substance abuse, traumatic brain injury and neuropsychological outcome.

The neuropsychological performance of 119 patients with severe closed traumatic brain injury (TBI) who had received toxicology screens at the time of trauma centre admission was examined. Three groups were created: normal screen, positive alcohol screen, or positive abused drugs screen (with or without the presence of alcohol). The admitting Glasgow Coma Scale (GCS) score was significantly lower in the positive alcohol screen group than the normal screen group, while the three groups did not differ in length of post-traumatic amnesia (PTA) or years of education. Neuropsychological assessment was conducted during inpatient rehabilitation, following resolution of PTA. Normal screen patients obtained significantly better scores than the abused-drugs patients on the Full Scale IQ (FIQ) and Verbal IQ (VIQ) indices of the Wechsler Adult Intelligence Scale-Revised and the Verbal Memory, General Memory, Attention-Concentration, and Delayed Recall indices of the Wechsler Memory Scale-Revised. Normal screen patients also scored significantly higher than positive alcohol screen patients on FIQ and VIQ indices and all five indices from the Wechsler Memory Scale-Revised. These data suggest the existence of an additive effect of substance abuse on neuropsychological outcome in TBI. Findings have potential implications for both acute management and rehabilitation of TBI.

Clinical evaluation and plasma clozapine concentrations in Chinese patients with schizophrenia.

The relationships between clozapine dosages, plasma concentrations, and clinical responses in Chinese schizophrenics were studied. Fourteen treatment-refractory schizophrenic patients were treated with clozapine for 12 weeks. Patients were assessed before and after 6 and 12 weeks of treatment using the Brief Psychiatric Rating Scale (BPRS), the Clinical Global Impression (CGI), and the Simpson-Angus Scale for Extrapyramidal Side Effect. Plasma clozapine concentrations were determined by high-performance liquid chromatography. Ten patients (71.4%) responded after 12 weeks of treatment. Although the mean daily dosage at week 12 (373 +/- 90 mg/day) was lower than that reported in American trials (444 mg/day), the mean plasma clozapine concentration attained (1,078 +/- 385 ng/ml) was higher. This higher concentration may be due to the lower body wight and the preponderance of women among our patients, absence of smoking and alcohol use, and/or ethnic difference between Chinese and non-Chinese. There was wide interindividual variation in the plasma clozapine concentrations. Compared with other studies, the plasma clozapine concentrations and the response rate were higher. Although the sample size was small, the findings are suggestive of pharmacokinetic and pharmacodynamic ethnic differences in Chinese with clozapine therapy.

A quantitative analysis of passive electrolocation behavior in electric fish.

Weakly electric fish of the families Gymnotidae and Hypopomidae (Gymnotiformes) are able to locate the electric discharges from conspecifics or from dipole electrodes, and they demonstrate this by making rapid, well-directed approaches toward these electrical sources. A video tracking system was used to follow the movements of electric fish in a large tank and an analytic method was used for computing the direction and magnitude of the electric field anywhere within the cylindrical test tank. Using a static analysis method, we describe the posture of test fish relative to the electric fields during their approaches to stationary or moving electrical stimuli. Using a dynamic analysis, we examine the movements of the fish including the sign and magnitude of velocity and bending in response to electric fields. Electric fish seek to maintain a zero error angle between their body orientation and the local electric field. They do so by bending their body in the direction of the local electric field. The response has a delay of approximately 0.5 s. Swimming in reverse inverts the direction of the bend. These fish also use 'V-turns' to redirect their swim directions when encountering rapidly-changing electric fields.

Short-range orientation in electric fish: an experimental study of passive electrolocation.

Gymnotiform electric fish are capable of locating and approaching an electrically discharging conspecific over a range of 1-2 m in a behavior called passive electrolocation. This paper investigates the movements of two species in experiments with approaches to stationary dipoles that are either silenced or jumped to a new direction during an approach. Gymnotus carapo fail to find an electrode source in trials in which the dipole electrode is switched off in mid-track. They slow their approach, become disoriented and drift away from the target within seconds of the field being switched off. This result suggests that the fish are unable to construct a cognitive map of a dipole source from brief exposure to local electrosensory stimuli. The second set of trials shows that Brachyhypopomus diazi and Gymnotus carapo bend their body to track electric vectors which are suddenly jumped to a new direction. The latency of the bend response is 0.5 s after the jump. Bending initiates a turn that reduces to zero the error between the fish's direction and the electric field vector and helps keep the fish aligned with the local electric field vector. Together, these experiments suggest that passive electrolocation is stimulus-bound and that these fish find the electrical sources simply by tracking instantaneous local electric current vectors.

Dyscalculia and dyslexia after right hemisphere injury in infancy.

OBJECTIVE: To use the findings from neuropsychological evaluation and functional magnetic resonance imaging (fMRI) to assess interhemispheric reorganization of function after early unilateral brain injury. DESIGN AND METHODS: The study focused on one case of early brain injury that resulted in both dyscalculia and dyslexia. Brain injury was studied using both structural and fMRI. Intellectual function was evaluated using the Wechsler Intelligence Scale for Children, Third Edition, while visuospatial skills were assessed using the Block Design subtest of the Wechsler Intelligence Scale for Children, Third Edition, and Judgment of Line Orientation subtest. The Selective Reminding Test and the Recurring Figures Test were used to evaluate memory and orientation; language and speech skills were evaluated using the Boston Naming Test, Controlled Oral Word Association, Gates-MacGinitie Reading Test, and color naming. Various methods were used to study arithmetic skills, including the Wide Range Achievement Test-Revised and the Peabody Individual Achievement Test. The control group for fMRI consisted of nine normal subjects. SETTING: Neuropsychological laboratory in primary care hospital. PATIENT: A 17-year-old boy who had sustained a closed head injury associated with a partially depressed, right parietal skull fracture, and right temporal hemorrhage in a motor vehicle crash at age 7 months (November 9, 1977). Subsequent social behavior was normal, but the patient had difficulty throughout school in mathematics and spelling and was characterized as having a "short attention span." INTERVENTION: None. MAIN OUTCOME MEASURES: Standardized tests of arithmetic and reading supplemented by an assessment of calculation and quantitative skills. While performing calculations, fMRI disclosed predominantly left hemisphere activation involving the frontal and posterior parietal regions, whereas this task produced bilateral activation of the supramarginal gyrus in seven of nine normal subjects. RESULTS: Neuropsychological findings confirmed the presence of dyscalculia and dyslexia despite normal intellectual functioning. Visuospatial skills ranged from the low normal to average level. The fMRI findings were consistent with early interhemispheric transfer of visuospatial skills normally committed to the right parietal area to the left parietal region. The patient's dyscalculia and reading ability raise a question of acquired left parietal dysfunction as a consequence of the competition between verbal and visuospatial functions for left hemisphere representation. CONCLUSION: Interhemispheric reorganization of function may be bidirectional rather than a feature unique to the left hemisphere substrate for language.

Selection of vascular access devices and nursing care.

OBJECTIVE: To provide an overview of the patient selection criteria for a vascular access device (VAD) and its maintenance care. CONCLUSIONS: The availability of different types of devices had led to confusion on the part of many health care professionals as to which device is the best for their purpose. Selecting the appropriate VAD is an interdisciplinary decision based on patient characteristics, type of therapy, support system availability, and cost. Numerous controversial issues surround the care of VADs, and research results have not yet resolved these practice issues. Although various procedures are used throughout the country, it can be reasonably concluded that the fundamental requirement for successful maintenance of a VAD is strict adherence to established care protocols. IMPLICATIONS FOR NURSING PRACTICE: Assessment of the need for a VAD is an ongoing process. Nurses are in a perfect position to assess the factors that precede device selection, including the frequency of access, type of intravenous therapy, and the condition of the patient's peripheral veins. The vast array of devices demands specialized knowledge in selecting the appropriate VAD, providing correct care, and evaluating the device once inserted or implanted.

The single-staff model for bone marrow transplantation.

This paper will demonstrate the advantages of pursuing an integrated model of care that utilizes one staff of caregivers in one facility for all phases of patient care from the time of patient evaluation through the time the patient returns to the care of his or her primary physician. We took the opportunity afforded by the development of a new program at the University of Alabama at Birmingham, the Bone Marrow Transplantation (BMT) Program, to reconsider as many variables as possible in an attempt to develop a model of care that would represent the best of all worlds, i.e., high levels of quality of care, quality of life, staff job enrichment, patient convenience, operational efficiency, and cost reduction.

Substance abuse as a factor in the causality, severity, and recurrence rate of traumatic brain injury.

The effects of substance abuse on the cause, severity, and recurrence of traumatic brain injury in 322 admissions to a large rehabilitation inpatient facility are explored. Study patients tended to be young and predominantly male. Few had completed high school and a significant minority had a history of cerebral dysfunction. Patients tended to have moderate to severe closed head injuries. Motor vehicle crashes were the most common cause of injury, but patients reporting drug or drug and alcohol abuse were more likely to sustain violent injuries (e.g., gunshot wounds).

Acute and chronic ultraviolet radiation induction of epidermal ornithine decarboxylase activity in hairless mice.

The effects of acute, multiple, and chronic exposure of hairless mice to ultraviolet radiation (UVR) on induction of epidermal ornithine decarboxylase (ODC) (EC 4.1.1.17) activity were investigated. Acute UVR exposure results in a biphasic time course of induction of epidermal ODC activity. Enzyme activity maxima occur at 3 and 24 h postirradiation. The biphasic time course is observed in two different strains of hairless mice (Skh:HR-1 and Jackson HRS/J) when the UVR source is either UBV fluorescent tubes or a solar simulator. The ratio of 24-h/3-h postirradiation ODC activity increases with increasing UVR dose. UVR induction of ODC activity was not significant below the mouse minimum erythemal dose (MED). The 3- and 24-h ODC activities have similar apparent Kms for ornithine (34 and 50 microM, respectively), and thermal stabilities at 52 degrees C (t1/2 = 23 and 18 min, respectively), and exhibit similar half-lives in vivo (t1/2 = 15 and 18 min, respectively). Multiple UVR exposure experiments showed 24-h ODC activity is sensitive to the preexposure history of the mouse, while 3-h ODC is not. Preexposure of hairless mice to several sub-MED levels of simulated solar radiation (SSR) specifically suppresses induction of 24-h ODC by a follow-up 2 x MED of SSR. Preexposure to a single 2 x MED of SSR specifically enhances induction of 24-h ODC induced by a second 2 x MED of SSR administered 48 h after the first. The 3-h ODC was not significantly affected by either preexposure regimen. Preexposure to a single high or low dose of UVA radiation did not affect epidermal ODC activity nor had an effect on ODC induction by UVB radiation. Several weeks of chronic exposure to UVB radiation elevated basal levels of epidermal ODC substantially (up to 350-fold). In these chronically irradiated mice, exposure to 2 x MED SSR resulted in a further 3.5-fold increase in ODC activity over the elevated basal level. These data reveal novel properties of epidermal cell expression of ODC activity in response to acute and chronic UVR insult. The results provide additional insight into the use of ODC as a marker for skin photodamage.

The week-old hip fracture: indication for prophylactic use of a vena cava filter? Report of two cases.

Occasional patients will present a week or more after sustaining a hip fracture. Though these patients are at high risk for asymptomatic deep venous thrombosis and pulmonary embolism, anticoagulation may be contraindicated prior to surgery. Two recent cases involving such a situation are reported. In the first, the patient sustained a fatal intraoperative pulmonary embolism. In the second, a transvenous Greenfield vena caval filter was placed prior to surgery. An extremely high suspicion of asymptomatic deep venous thrombosis is necessary when evaluating a patient whose hip fracture has been untreated for a week or more. If studies demonstrate a deep venous thrombosis preoperatively, placement of an inferior vena caval filter may be indicated.