Rapidly solidified titanium alloys by melt overflow

A pilot plant scale furnace was designed and constructed for casting titanium alloy strips. The furnace combines plasma arc skull melting techniques with melt overflow rapid solidification technology. A mathematical model of the melting and casting process was developed. The furnace cast strip of a suitable length and width for use with honeycomb structures. Titanium alloys Ti-6Al-4V and Ti-14Al-21 Nb were successfully cast into strips. The strips were evaluated by optical metallography, microhardness measurements, chemical analysis, and cold rolling

Antibiotic Resistance Profile of CTX-M-type Extended-Spectrum Beta-Lactamases in Escherichia coli and Klebsiella pneumoniae in Accra, Ghana

Extended-spectrum beta-lactamases (ESBLs) are plasmid-mediated beta lactamases that are capable of hydrolysing beta-lactams except carbapenems and cephamycins. The most common ESBL types include CTX-M, TEM and SHV. This genetic diversity in the various ESBL-producing organisms may reflect characteristic differences in relation to pathogenesis, antibiotic resistance expression, response to therapy, transmission and infection control. This work sought to determine the characteristic antibiotic minimum inhibition concentrations (MICs) and antimicrobial sensitivity profile of CTX-M-type ESBLs in Accra. Hundred (100) DNA templates were extracted from ESBL-producing K. pneumoniae and E. coli isolates. The specific ESBL types were determined by polymerase chain reaction with specific primers and reaction conditions. The MICs of the antibiotics were determined using Vitek 2 Compact System (bioMérieux, Marcy I’Etoile, France). The results showed that CTX-M-type ESBL have cefotaxime MIC in the resistant range of >64 µg/ml. The CTX-M-type ß-lactamases showed co-resistances to gentamicin (88.6%), tetracycline (71.4%), trimethoprim-sulphamethoxazole (98.6%).The resistance of CTX-M-type ESBL producing organisms to fluoroquinolones have been well established in this work with resistances in ciprofloxacin (71.4%) and norfloxacin (71.4%) with MIC90 being >4 µg/ml and >16 µg/ml respectively. The beta-lactam-beta-lactamase inhibitor combination of piperacillin-tazobactam was more susceptible to CTX-M-type ESBL than amoxicillin-clavulanate. Imipenem and amikacin has been established as the in vitro drug of choice for the management of organisms producing CTX-M-type ESBL in this present work. Efforts should be made to control the increasing prevalence of CTX-M-type producing organisms in the communities and hospital settings in Accra with their adverse multiple-drug resistance. Keywords: Extended spectrum beta-lactamase, CTX-M-type ESBL, Resistance, Antibiotics

Antibiotic Resistance Profile of Non-Extended Spectrum Beta-Lactamase-producing Escherichia coli and Klebsiella pneumoniae in Accra, Ghana

One of the major challenges facing health professionals is the prevalence of antibiotic resistance. Most Gram-negative bacteria produce beta-lactamases which are enzymes that in-activate ?-lactams. Recent publications suggested that extended spectrum beta-lactamase production in E. coli and K. pneumoniae is one of the main causes of antimicrobial resistance in penicillins, cephalosporins and some non-beta-lactam antibiotics in Accra. This present work sought to determine the resistance profile of antimicrobials to non-ESBL-producing isolates in Accra. The 400 K. pneumoniae and E. coli isolates were screened for non-ESBL-producing strains using the combined disk method. The minimum inhibition concentration for 17 antibiotics was determined using Vitek 2 Compact System (bioMérieux, Marcy I’Etoile, France).  Among the 400 total bacterial isolates, 198 (49.5%) were non-ESBL producers. Co-resistances to ampicillin (66.7%), piperacillin (59.1%), tetracycline (77.8%) and trimethoprim/sulphamethoxazole (68.2%) have been collaborated in this work. The increasing rise in resistance to the beta-lactam/beta-lactamase inhibitor combination antibiotics such as amoxicillin/clavulanic acid (13.6%) and piperacillin/tazobactam (18.7%) is problematic since they have become the empirical drug of choice for treating most infections. The steady increase in resistance to gentamicin (17.2%) as well as the floroquinolones such as ciprofloxacin (39.4%) and norfloxacin (34.9%) is alarming. In the absence of ESBLs, cephalosporins generally have been effective in treating infections caused by enterobacteria. Nitrofurantoin remains reliable for managing non-life threatening urinary tract infections. Amikacin and imipenem continue to be effective third-line treatment options for Gram-negative bacteria infections.  As antibiotic resistance increases and the development of new antimicrobials declines, it is imperative that we use antimicrobials that are still effective rationally. Evidence based antibiotic prescriptions and usage as well as regular evaluation of antibiotic resistance will help to control the spread of antibiotic resistance in Accra, Ghana. Keywords: Extended spectrum beta-lactamase, Resistance, Antibioti

Expert Discovery Protections: Comparing District Courts with the PTAB

Expert witness testimony can be critical in patent litigation in all forums. In Patent Trial and Appeal Board (“PTAB”) proceedings, particularly inter partes review (“IPR”) and post-grant review (“PGR”), expert testimony through declarations and depositions plays a central role in both challenging and defending patents. In district courts, live expert testimony is key to proving infringement and invalidity. Accordingly, the legal protections governing the disclosure of expert testimony in discovery in both forums are carefully proscribed, but with notable distinctions

Hidden magnetic fields of young suns

Global magnetic fields of active solar-like stars are, nowadays, routinely detected with spectropolarimetric measurements and are mapped with Zeeman Doppler imaging (ZDI). However, due to the cancellation of opposite field polarities, polarimetry only captures a tiny fraction of the magnetic flux and cannot assess the overall stellar surface magnetic field if it is dominated by a small-scale component. The analysis of Zeeman broadening in high-resolution intensity spectra can reveal these hidden complex magnetic fields. Historically, there were very few attempts to obtain such measurements for G dwarf stars due to the difficulty of disentangling the Zeeman effect from other broadening mechanisms affecting spectral lines. Here, we developed a new magnetic field diagnostic method based on relative Zeeman intensification of optical atomic lines with different magnetic sensitivity. By using this technique, we obtained 78 field strength measurements for 15 Sun-like stars, including some of the best-studied young solar twins. We find that the average magnetic field strength Bf drops from 1.3-2.0 kG in stars younger than about 120 Myr to 0.2-0.8 kG in older stars. The mean field strength shows a clear correlation with the Rossby number and with the coronal and chromospheric emission indicators. Our results suggest that magnetic regions have roughly the same local field strength B approximate to 3.2 kG in all stars, with the filling factor f of these regions systematically increasing with stellar activity. In comparing our results with the spectropolarimetric analyses of global magnetic fields in the same stars, we find that ZDI recovers about 1% of the total magnetic field energy in the most active stars. This figure drops to just 0.01% for the least active targets.Peer reviewe

Socioeconomic status and the brain: mechanistic insights from human and animal research

Human brain development occurs within a socioeconomic context and childhood socioeconomic status (SES) influences neural development — particularly of the systems that subserve language and executive function. Research in humans and in animal models has implicated prenatal factors, parent–child interactions and cognitive stimulation in the home environment in the effects of SES on neural development. These findings provide a unique opportunity for understanding how environmental factors can lead to individual differences in brain development, and for improving the programmes and policies that are designed to alleviate SES-related disparities in mental health and academic achievement

Modelling job crafting behaviours: Implications for work engagement

In this study among 206 employees (103 dyads), we followed the job demands–resources approach of job crafting to investigate whether proactively changing one’s work environment influences employee’s (actor’s) own and colleague s (partner’s) work engagement. Using social cognitive theory, we hypothesized that employees would imitate each other’s job crafting behaviours, and therefore influence each other’s work engagement. Results showed that the crafting of social and structural job resources, and the crafting of challenge job demands was positively related to own work engagement, whereas decreasing hindrance job demands was unrelated to own engagement. As predicted, results showed a reciprocal relationship between dyad members’ job crafting behaviours – each of the actor’s job crafting behaviours was positively related to the partner’s job crafting behaviours. Finally, employee’s job crafting was related to colleague’s work engagement through colleague’s job crafting, suggesting a modelling process

Co-registered combined OCT and THz imaging to extract depth and refractive index of a tissue-equivalent test object

Terahertz (THz) imaging and optical coherence tomography (OCT) provide complementary information with similar length scales. In addition to OCT’s extensive use in ophthalmology, both methods have shown some promise for other medical applications and non-destructive testing. In this paper, we present an iterative algorithm that combines the information from OCT and THz imaging at two different measurement locations within an object to determine both the depth of the reflecting layers at the two locations and the unknown refractive index of the medium for both the OCT wavelengths and THz frequencies. We validate this algorithm using a silicone test object with embedded layers and show that the depths and refractive index values obtained from the algorithm agreed with the measured values to within 3.3%. We further demonstrate for the first time that OCT and THz images can be co-registered and aligned using unsupervised image registration. Hence we show that a combined OCT/THz system can provide unique information beyond the capability of the separate modalities alone, with possible applications in the medical, industrial and pharmaceutical sectors

Doppler images and the underlying dynamo. The case of AF Leporis

The (Zeeman-)Doppler imaging studies of solar-type stars very often reveal large high-latitude spots. This also includes F stars that possess relatively shallow convection zones, indicating that the dynamo operating in these stars differs from the solar dynamo. We aim to determine whether mean-field dynamo models of late-F type dwarf stars can reproduce the surface features recovered in Doppler maps. In particular, we wish to test whether the models can reproduce the high-latitude spots observed on some F dwarfs. The photometric inversions and the surface temperature maps of AF Lep were obtained using the Occamian-approach inversion technique. Low signal-to-noise spectroscopic data were improved by applying the least-squares deconvolution method. The locations of strong magnetic flux in the stellar tachocline as well as the surface fields obtained from mean-field dynamo solutions were compared with the observed surface temperature maps. The photometric record of AF Lep reveals both long- and short-term variability. However, the current data set is too short for cycle-length estimates. From the photometry, we have determined the rotation period of the star to be 0.9660+-0.0023 days. The surface temperature maps show a dominant, but evolving, high-latitude (around +65 degrees) spot. Detailed study of the photometry reveals that sometimes the spot coverage varies only marginally over a long time, and at other times it varies rapidly. Of a suite of dynamo models, the model with a radiative interior rotating as fast as the convection zone at the equator delivered the highest compatibility with the obtained Doppler images.Comment: accepted for publication in Astronomy & Astrophysic