244 research outputs found
Forensic touch DNA recovery from metal surfaces - a review
Trace evidence such as touch (also known as contact) DNA has probative value as a vital forensic investigative tool that can lead to the identification and apprehension of a criminal. While the volume of touch DNA evidence items submitted to forensic laboratories has significantly increased, recovery and amplification of DNA from these items, especially from metal surfaces, remains challenging. Currently little is understood with regards to the underlying mechanisms of metal-DNA interactions in the context of forensic science and how this may impact on DNA recovery. An increased understanding of these mechanisms would allow optimisation of methods to improve outcomes when sampling these materials. This paper reviews the basis of DNA binding to metal substrates, the merits and limitations of current methods and future perspectives of improving recovery and amplification of touch DNA from metal surfaces of forensic interest.Dan Osei Mensah Bonsu, Denice Higgins, Jeremy J. Austi
Differences in students’ understanding of opportunity process matters for their learning!
Despite different views on opportunities and opportunities identification, there
seems to be consensus about the significant role of opportunities in the entrepreneurship
process and for the success of the entrepreneur (Shane & Venkataraman 2000, Eckhardt
& Shane 2003, Gaglio & Katz 2001). However, even though opportunities, depending
on the purpose and contributor, are regarded as a core element, process or competence
in entrepreneurship, it is only recently that the question of how to teach or learn these
opportunity-related competences has started to attract scholars (Saks & Gaglio 2002,
Corbett 2005, Lumpkin & Lichtenstein 2005). The problem is that how the nature and
process of opportunities are understood has an effect on learning and teaching practices.
We argue that the differences in understanding what opportunities are have
effect on how to learn and teach opportunity competences. The starting point though
should be the knowledge about how students understand what opportunities are and
how they want to enhance their competences related to the opportunity process.
Consequently, the aim of our research is to understand how students understand
opportunity process. First, we identify different theoretical approaches to the
opportunity process from the learning perspective. Then, we investigate (basing on 16
writings), how students understand what opportunities are in the venture creation
process with respect to these different approaches and, finally, we elaborate what this
means for learning and teaching practices.
On the basis of the theories of Cantillon (1931), Mises (1949) and Kirzner
(1963) regarding human beings as central to entrepreneurship, our study identifies three
approaches through which the opportunity process could take place: search, discovery,
action. Empirical analysis validates proposed division. We conclude that courses aimed
at opportunity enhancement should be designed in a way that students increase their
awareness of the different nature of an opportunity and its process, as well as the
varying nature of human involvement in opportunity processes. Entrepreneurship
education should not be to look for uniform methods and teaching tools, but to try to
combine them in order to enable all students to learn and increase their competences
Missed Opportunities for the Diagnosis of Pulmonary Tuberculosis in Ashanti and Western Regions of Ghana; Polymerase Chain Reaction, A Better Tool
The diagnosis of Pulmonary Tuberculosis (PTB) has mainly relied on sputum microscopy and culture. The use of molecular techniques such as the Polymerase Chain Reaction (PCR) and its overwhelming advantages compared with conventional diagnostic methodologies cannot be overemphasized. The main aim of this work was to compare the diagnostic sensitivities of microscopy, culture and PCR. Suspected PTB sputum samples were prospectively collected from six hospitals in the Ashanti and Western regions of Ghana. Microscopy was carried out on all samples at the field sites. Apart from culture and PCR, repeat sputum microscopy was carried out in the laboratories of the Kumasi Centre for Collaborative Research (KCCR). Out of the total 425 cases recruited for the study, 123 (29.0%) were smear positive on site in contrast to 275 (64.7%) positivity rate at KCCR. Regarding culture, 254 (59.9%) samples were culture positive whilst PCR technique using INS 1&2 and PR 8&9 primers were positive in 59.9 % and 56% of cases respectively. The proportion of missed positive cases of microscopy were 131 (51%) compared with culture and 1.1% missed cases when compared with PCR. The sensitivity and specificity of microscopy were 123/254 (48.4%) and 154/302 (50.99%). The study confirms the superiority of PCR in the diagnosis of PTB and indicates that a substantial proportion of PTB cases are missed when microscopy alone is used. In areas where the incidence of PTB is high and at referral hospitals, PCR can be done to augment the diagnosis of TB.Keywords: Pulmonary Tuberculosis, Sputum Microscopy, Culture, Polymerase Chain Reactio
Evaluation of the efficiency of Isohelix TM and Rayon swabs for recovery of DNA from metal surfaces
Published online: 12 November 2020Purpose We investigated the recovery and extraction efficiency of DNA from three metal surfaces (brass, copper, steel) relevant to forensic casework, and plastic (control) using two different swabbing systems; Rayon and Isohelix™ swabs, with sterile water and isopropyl alcohol respectively, as the wetting solutions. Methods Twenty nanograms of human genomic DNA were applied directly to Isohelix™ and Rayon swabs; and to the metal and plastic substrates. All substrates were left to dry for 24 h, followed by single wet swabbing and extraction with the DNA IQ™ System. DNA extracts were quantified using real time quantitative PCR assays with SYBR green chemistry. Results DNA was extracted from directly seeded Isohelix™ swabs with a high efficiency of 98%, indicating effective DNArelease from the swab into the extraction buffer. In contrast, only 58% of input DNA was recovered from seeded Rayon swabs, indicating higher DNA retention by these swabs. Isohelix™ swabs recovered 32 – 53% of DNA from metal surfaces, whilst the Rayon swabs recovered 11—29%. DNA recovery was lowest from copper and highest from brass. Interestingly, Rayon swabs appeared to collect more DNA from the plastic surface than Isohelix™ swabs, however, due to the lower release of DNA from Rayon swabs they returned less DNA overall following extraction than Isohelix™ swabs. Conclusion These results demonstrate that DNA samples deposited on metal surfaces can be more efficiently recovered using Isohelix™ swabs wetted with isopropyl alcohol than Rayon swabs wetted with sterile water, although recovery is affected by the substrate type.Dan O. M. Bonsu, Denice Higgins, Julianne Henry, Jeremy J. Austi
Abnormal Visuo-vestibular Interactions in Vestibular Migraine: a Cross Sectional Study
Vestibular migraine is amongst the commonest causes of episodic vertigo. Chronically, patients with vestibular migraine develop abnormal responsiveness to both vestibular and visual stimuli characterised by heightened self-motion sensitivity and visually-induced dizziness. Yet, the neural mechanisms mediating such symptoms remain unknown. We postulate that such symptoms are attributable to impaired visuo-vestibular cortical interactions, which in-turn disrupts normal vestibular function. To assess this, we investigated whether prolonged, full-field visual motion exposure, which has previously been shown to modulate visual cortical excitability in both healthy individuals and avestibular patients, could disrupt vestibular ocular reflex (VOR) and vestibular-perceptual thresholds of self-motion during rotations. Our findings reveal that vestibular migraine patients exhibited abnormally elevated reflexive and perceptual vestibular thresholds at baseline. Following visual motion exposure, both reflex and perceptual thresholds were significantly further increased in vestibular migraine patients relative to healthy controls, migraineurs without vestibular symptoms and patients with episodic vertigo due to a peripheral inner-ear disorder. Our results provide support for the notion of altered visuo-vestibular cortical interactions in vestibular migraine, as evidenced by vestibular threshold elevation following visual motion exposure
The Costs of Implementing Vaccination With the RTS,S Malaria Vaccine in Five Sub-Saharan African Countries.
Background. The World Health Organization has recommended pilot implementation of a candidate vaccine against malaria (RTS,S/AS01) in selected sub-Saharan African countries. This exploratory study aimed to estimate the costs of implementing RTS,S in Burkina Faso, Ghana, Kenya, Mozambique, and Tanzania. Methods. Key informants of the expanded program on immunization at all levels in each country were interviewed on the resources required for implementing RTS,S for routine vaccination. Unit prices were derived from the same sources or from international price lists. Incremental costs in 2015 US dollars were aggregated per fully vaccinated child (FVC). It was assumed the four vaccine doses were either all delivered at health facilities or the fourth dose was delivered in an outreach setting. Results. The costs per FVC ranged from US37 (Kenya) assuming a vaccine price of US1 regardless of the country. Conclusions. This study provides relevant information for donors and decision makers about the cost of implementing RTS,S. Variations within and across countries are important and the unknown future price per dose and wastage rate for this candidate vaccine adds substantially to the uncertainty about the actual costs of implementation
Missed opportunities for tuberculosis investigation in a municipal hospital in Ghana: evidence from patient exit interviews.
BACKGROUND: We assessed coverage of symptom screening and sputum testing for tuberculosis (TB) in hospital outpatient clinics in Ghana. METHODS: In a cross-sectional study, we enrolled adults (≥18 years) exiting the clinics reporting ≥1 TB symptom (cough, fever, night sweats or weight loss). Participants reporting a cough ≥2 weeks or a cough of any duration plus ≥2 other TB symptoms (per national criteria) and those self-reporting HIV-positive status were asked to give sputum for testing with Xpert MTB/RIF. RESULTS: We enrolled 581 participants (median age 33 years [IQR: 24-48], 510/581 [87.8%] female). The most common symptoms were fever (348, 59.9%), chest pain (282, 48.5%) and cough (270, 46.5%). 386/581 participants (66.4%) reported symptoms to a healthcare worker, of which 157/386 (40.7%) were eligible for a sputum test per national criteria. Only 31/157 (19.7%) had a sputum test requested. Thirty-two additional participants gave sputum among 41 eligible based on positive HIV status. In multivariable analysis, symptom duration ≥2 weeks (adjusted odds ratio [aOR] 6.99, 95% confidence interval [CI] 2.08-23.51) and previous TB treatment (aOR: 6.25, 95% CI: 2.24-17.48) were the strongest predictors of having a sputum test requested. 6/189 (3.2%) sputum samples had a positive Xpert MTB/RIF result. CONCLUSION: Opportunities for early identification of people with TB are being missed in health facilities in Ghana
'I'm passionate, Lord Sugar'::Young Entrepreneurs, Critical Judgment and Emotional Labor in Young Apprentice
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