Nanoscale Imaging and Control of Resistance Switching in VO[sub]2 at Room Temperature

We demonstrate controlled local phase switching of a VO[sub]2 film using a biased conducting atomic force microscope tip. After application of an initial, higher ‘training’ voltage, the resistance transition is hysteretic with IV loops converging upon repeated voltage sweep. The threshold Vset to initiate the insulator-to-metal transition is on order ∼ 5 V at room temperature, and increases at low temperature. We image large variations in Vset from grain to grain. Our imaging technique opens up the possibility for an understanding of the microscopic mechanism of phase transition in VO[sub]2 as well as its potential relevance to solid state devices.Engineering and Applied SciencesPhysic

PhenDisco: phenotype discovery system for the database of genotypes and phenotypes.

The database of genotypes and phenotypes (dbGaP) developed by the National Center for Biotechnology Information (NCBI) is a resource that contains information on various genome-wide association studies (GWAS) and is currently available via NCBI's dbGaP Entrez interface. The database is an important resource, providing GWAS data that can be used for new exploratory research or cross-study validation by authorized users. However, finding studies relevant to a particular phenotype of interest is challenging, as phenotype information is presented in a non-standardized way. To address this issue, we developed PhenDisco (phenotype discoverer), a new information retrieval system for dbGaP. PhenDisco consists of two main components: (1) text processing tools that standardize phenotype variables and study metadata, and (2) information retrieval tools that support queries from users and return ranked results. In a preliminary comparison involving 18 search scenarios, PhenDisco showed promising performance for both unranked and ranked search comparisons with dbGaP's search engine Entrez. The system can be accessed at http://pfindr.net

Assignment of Streptococcus agalactiae isolates to clonal complexes using a small set of single nucleotide polymorphisms

<p>Abstract</p> <p>Background</p> <p><it>Streptococcus agalactiae </it>(Group B Streptococcus (GBS)) is an important human pathogen, particularly of newborns. Emerging evidence for a relationship between genotype and virulence has accentuated the need for efficient and well-defined typing methods. The objective of this study was to develop a single nucleotide polymorphism (SNP) based method for assigning GBS isolates to multilocus sequence typing (MLST)-defined clonal complexes.</p> <p>Results</p> <p>It was found that a SNP set derived from the MLST database on the basis of maximisation of Simpsons Index of Diversity provided poor resolution and did not define groups concordant with the population structure as defined by eBURST analysis of the MLST database. This was interpreted as being a consequence of low diversity and high frequency horizontal gene transfer. Accordingly, a different approach to SNP identification was developed. This entailed use of the "Not-N" bioinformatic algorithm that identifies SNPs diagnostic for groups of known sequence variants, together with an empirical process of SNP testing. This yielded a four member SNP set that divides GBS into 10 groups that are concordant with the population structure. A fifth SNP was identified that increased the sensitivity for the clinically significant clonal complex 17 to 100%. Kinetic PCR methods for the interrogation of these SNPs were developed, and used to genotype 116 well characterized isolates.</p> <p>Conclusion</p> <p>A five SNP method for dividing GBS into biologically valid groups has been developed. These SNPs are ideal for high throughput surveillance activities, and combining with more rapidly evolving loci when additional resolution is required.</p

Adverse drug reactions in Ghanaian children: review of reports from 2000 to 2012 in VigiBase

Objective: The aim of this article is to describe adverse drug reactions (ADRs) reported for children aged 0 - 17 years in Ghana. Methods: Paediatric reports submitted by the Ghana National Centre for Pharmacovigilance to the World Health Organisation (WHO) Global ADR database, VigiBase up to December 2012 were extracted. The data were analysed for number of reports per year, types of reporters and suspected ADRs and drugs. Results: A total of 343 reports for children were received during the period. The drug classes most frequently reported were vaccines (115, 31%), antimalarials (106, 28%) and antibiotics (57, 15%). Of the top 20 individual drugs, 19 were anti-infectives. The most frequently reported ADRs were injection site infection, fever and rash. There were 23 deaths reported, and antimalarials were implicated in 12 cases. Conclusions: Vaccines, antimalarials and antibiotics are the leading medicines reported to cause ADRs in Ghanaian children. There was a high mortality rate, with many of the deaths due to causes explained in the individual case safety reports

Ex vivo detection and characterization of early dental caries by optical coherence tomography and Raman spectroscopy.

Early dental caries detection will facilitate implementation of nonsurgical methods for arresting caries progression and promoting tooth remineralization. We present a method that combines optical coherence tomography (OCT) and Raman spectroscopy to provide morphological information and biochemical specificity for detecting and characterizing incipient carious lesions found in extracted human teeth. OCT imaging of tooth samples demonstrated increased light backscattering intensity at sites of carious lesions as compared to the sound enamel. The observed lesion depth on an OCT image was approximately 290 mm matching those previously documented for incipient caries. Using Raman microspectroscopy and fiber-optic- based Raman spectroscopy to characterize the caries further, spectral changes were observed in PO 42 vibrations arising from hydroxyapa- tite of mineralized tooth tissue. Examination of various ratios of PO 42 n 2 , n 3 , n 4 vibrations against the n 1 vibration showed consistent in- creases in carious lesions compared to sound enamel. The changes were attributed to demineralization-induced alterations of enamel crystallite morphology and/or orientation. OCT imaging is useful for screening carious sites and determining lesion depth, with Raman spectroscopy providing biochemical confirmation of caries. The com- bination has potential for development into a new fiber-optic diagnos- tic tool enabling dentists to identify early caries lesions with greater sensitivity and specificity. © 2005 Society of Photo-Optical Instrumentation Engi

Electromagnetic navigation transthoracic needle aspiration for the diagnosis of pulmonary nodules: A safety and feasibility pilot study

BACKGROUND: Pulmonary nodules remain a diagnostic challenge for physicians. Minimally invasive biopsy methods include bronchoscopy and CT guided transthoracic needle aspiration (TTNA). A novel electromagnetic guidance transthoracic needle aspiration (ETTNA) procedure which can be combined with navigational bronchoscopy (NB) and endobronchial ultrasound (EBUS) in a single setting has become available. METHODS: A prospective pilot study examining the safety, feasibility and diagnostic yield of ETTNA in a single procedural setting. All patients enrolled underwent EBUS for lung cancer staging followed by NB and ETTNA. Feasibility of performing ETTNA and a safety assessment by recording procedural related complications including pneumothorax or bleeding was performed. Diagnostic yield of ETTNA defined by a definitive pathologic tissue diagnosis was recorded. An additional diagnostic yield analysis was performed using a cohort analysis of combined interventions (EBUS + NB + ETTNA). All non-diagnostic biopsies were either followed with radiographic imaging or a surgical biopsy was performed. RESULTS: Twenty-four subjects were enrolled. ETTNA was feasible in 96% of cases. No bleeding events occurred. There were five pneumothoraces (21%) of which only two (8%) subjects required drainage. The diagnostic yield for ETTNA alone was 83% and increased to 87% (P=0.0016) when ETTNA was combined with NB. When ETTNA and NB were performed with EBUS for complete staging, the diagnostic yield increased further to 92% (P=0.0001). CONCLUSIONS: This is the first human pilot study demonstrating an acceptable safety and feasibility profile with a novel ETTNA system. Further studies are needed to investigate the increased diagnostic yield from this pilot study

Sentinel Lymph Node Radiolocalization with 99mTc Filtered Tin Colloid in Clinically Node-Negative Squamous Cell Carcinomas of the Oral Cavity

The objective of this study was to evaluate the feasibility of sentinel lymph node biopsy by using a radiotracer lymphatic mapping technique in patients with squamous cell carcinoma of the oral cavity, and the diagnostic value of this technique. We studied twenty patients with previously untreated squamous cell carcinomas of the oral cavity and N0 necks. After the peritumoral injection of 99mTc filtered tin colloid preop-eratively, lymphoscintigraphy and intraoperative mapping using a gamma detector were performed to localize sentinel nodes. An open biopsy of the sentinel node was followed by complete neck dissection. We identified the sentinel nodes in 19 of 20 patients (95.0%) by lymphoscintigraphy and in all (100%) by intraoperative gamma detector. In all cases, the status of the sentinel node accurately predicted the pathologic status of the neck with the false negative rate being 0%. The negative predictive value for the absence of cervical metastases was 100%. In conclusion, our radio-localization technique of sentinel nodes using 99mTc filtered tin colloid in N0 squamous cell carcinomas of the oral cavity is technically feasible and appears to accurately predict the presence of the occult metastatic disease

End-user perceptions of a patient-and family-centred intervention to improve nutrition intake among oncology patients: A descriptive qualitative analysis

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