In vitro template-change PCR to create single crossover libraries: a case study with B. thuringiensis Cry2A toxins

During evolution the creation of single crossover chimeras between duplicated paralogous genes is a known process for increasing diversity. Comparing the properties of homologously recombined chimeras with one or two crossovers is also an efficient strategy for analyzing relationships between sequence variation and function. However, no well-developed in vitro method has been established to create single-crossover libraries. Here we present an in vitro template-change polymerase change reaction that has been developed to enable the production of such libraries. We applied the method to two closely related toxin genes from B. thuringiensis and created chimeras with differing properties that can help us understand how these toxins are able to differentiate between insect species

Special Issue: Recent advances (2008 – 2015) in the study of ground ice and cryostratigraphy

Cryostratigraphy involves the description, interpretation and correlation of ground-ice 17 structures (cryostructures) and their relationship to the host deposits. Recent advances in the 18 study of ground ice and cryostratigraphy concern permafrost aggradation and degradation, 19 massive-ice formation and evaluation of ground-ice content. Field studies have increased our 20 knowledge of cryostructures and massive ground ice in epigenetic and syngenetic permafrost. 21 Epigenetic permafrost deposits are relatively ice-poor and composed primarily of pore-filled 22 cryostructures, apart from an ice-enriched upper section and intermediate layer. Syngenetic 23 permafrost deposits are commonly identified from cryostructures indicative of an aggrading 24 permafrost table and are characterized by a high ice content, ice-rich cryofacies, and nested 25 wedge ice. Degradation of ice-rich permafrost can be marked by thaw unconformities, 26 truncated buried ice wedges, ice-wedge pseudomorphs, and organic-rich ‘forest beds’. 27 Studies of massive ground ice have focused on wedge ice, thermokarst-cave ice, intrusive ice, 28 and buried ice. Significant advances have been made in methods for differentiating between 29 tabular massive ice bodies of glacier and intrasedimental origin. Recent studies have utilized 30 palynology, isotope geochemistry and hydrochemistry, in addition to sedimentary and 31 cryostratigraphic analyses. The application of remote sensing techniques and laboratory 32 methods such as CT scanning has improved estimations of the ice content of frozen 33 sediments

The Effects of Musical Training on Speech Detection in the Presence of Informational and Energetic Masking

Recent research has suggested that musicians have an advantage in some speech-in-noise paradigms, but not all. Whether musicians outperform nonmusicians on a given speech-in-noise task may well depend on the type of noise involved. To date, few groups have specifically studied the role that informational masking plays in the observation of a musician advantage. The current study investigated the effect of musicianship on listeners’ ability to overcome informational versus energetic masking of speech. Monosyllabic words were presented in four conditions that created similar energetic masking but either high or low informational masking. Two of these conditions used noise-vocoded target and masking stimuli to determine whether the absence of natural fine structure and spectral variations influenced any musician advantage. Forty young normal-hearing listeners (20 musicians and 20 nonmusicians) completed the study. There was a significant overall effect of participant group collapsing across the four conditions; however, planned comparisons showed musicians’ thresholds were only significantly better in the high informational masking natural speech condition, where the musician advantage was approximately 3 dB. These results add to the mounting evidence that informational masking plays a role in the presence and amount of musician benefit

Description, Normative Data, and Utility of the Hearing Aid Skills and Knowledge Test.

AbstractThe ability to manage hearing aids is crucial for successful outcomes and for maintaining hearing aid use. It is therefore important to have a tool that can effectively identify which hearing aid management skills are lacking so that the audiologist can provide additional education and training on that skill. Such a tool can also provide useful quantitative data for researchers.To collect normative data (Experiment 1) and assess inter- and intrarater reliability (Experiment 2) for a hearing aid management assessment tool known as the Hearing Aid Skills and Knowledge (HASK) test.Two hundred thirty-six new hearing aid users recruited from the VA Portland Health Care System and 126 experienced hearing aid users recruited from the local Portland community participated in Experiment 1. The veteran participants were taking part in a larger hearing aid study, and the community participants were recruited at community events that took place around Portland, OR. Three clinical audiologists and two AuD students completing their fourth year externship participated in Experiment 2.In Experiment 1, HASK data were collected from the new hearing aid users at 4–8 wk and 6–8 mo after the fitting of their first pair of hearing aids, and from experienced users on a single occasion. In addition, self-reported hearing aid use, benefit, and satisfaction were assessed for all participants. The audiologists/students in Experiment 2 watched and independently scored videos of six individuals completing the HASK. Intraclass correlation coefficients (ICCs) across audiologists were computed for HASK scores. Three audiologists/students rated at least one video on two occasions to provide interrater reliability data.Mean performance on the HASK was about 70% for knowledge and 80% for skills for both the new and experienced hearing aid users. Performance did not change among the new users between the 4–8 wk and 6–8 mo administration. The specific skills lacking were associated with advanced management abilities (cleaning and troubleshooting). Experiment 2 revealed ICCs for inter- and intrarater reliability for HASK to range from 0.76 to 0.94, showing acceptable to excellent reliability.The HASK is a quick and easy test with good-to-excellent inter- and intrarater reliability. It can effectively identify which hearing aid management skills are lacking so that the audiologist can provide additional education and training on those skills. Data show performance is ∼70% for knowledge and 80% for skills and this does not change with hearing aid experience. The significant positive correlations between HASK scores and hearing aid use and satisfaction highlight the notion that ability to manage hearing aids successfully is integral to good hearing aid outcome.</jats:p

Investigating the effect of blurring and focusing current in cochlear implant users with the Panoramic ECAP method

Purpose: For some cochlear implants (CIs), it is possible to focus electrical stimulation by partially returning current from the active electrode to adjacent, intra-cochlear electrodes (partial tripolar (pTP) stimulation). Another method achieves the opposite: “blurring” by stimulating multiple electrodes simultaneously. The Panoramic ECAP Method (PECAP) provides a platform to investigate their effects in detail by measuring Electrically-Evoked Compound Action-Potentials (ECAPs) and estimating current spread and neural responsiveness along the length of the CI electrode array. We investigate how sharpening and broadening the electrical current spread is reflected in PECAP estimates. Methods: PECAP measurements were recorded at most comfortable level in 12 ears of Advanced Bionics CI users. Focused thresholds were also determined using steered quadrupolar (sQP) stimulation. For the electrodes with the highest and lowest sQP thresholds, additional PECAP measurements were recorded whilst stimulating in pTP mode and in “blurred” mode with 3 or 5 adjacent electrodes simultaneously stimulated. Current spread and neural responsiveness were then estimated along the electrode array using PECAP. Results: PECAP revealed increased current-spread estimates for blurred stimulation for the targeted electrodes towards the apex of the cochlea. Mixed results for pTP stimulation were found, with increased current spread in two ears, decreased current spread in one ear, and no effect in five. Conclusion: When stimulating multiple electrodes simultaneously, PECAP detected localized increases in current spread toward the apex (but not the base) of the cochlea. pTP stimulation showed mixed effects on PECAP current-spread estimates. These findings are in line with behavioral speech perception studies