Clinical experience with amikacin, a new aminoglycoside antibiotic

CITATION: Theron, F. P. & De Kock, M. A. 1977. Clinical experience with amikacin, a new aminoglycoside antibiotic. South African Medical Journal, 51(21):746-8.The original publication is available at http://www.samj.org.za[No abstract available]Publisher’s versio

Bosonization in d=2 from finite chiral determinants with a Gauss decomposition

We show how to bosonize two-dimensional non-abelian models using finite chiral determinants calculated from a Gauss decomposition. The calculation is quite straightforward and hardly more involved than for the abelian case. In particular, the counterterm $A\bar A$, which is normally motivated from gauge invariance and then added by hand, appears naturally in this approach.Comment: 4 pages, Revte

Evaluating the Impacts of Hunting Paths on Northern Bobwhite Survival, Economic Costs, and Hunter Satisfaction

The amount and spatial configuration of habitat is known to influence the abundance, movements, resource use, and persistence of many species. As such, land managers must be judicious in their application of management actions to minimize its impact on wildlife while concurrently providing recreational opportunities. Mowing or roller-chopping is a common management technique implemented on intensively managed northern bobwhite (Colinus virginianus) plantations to increase hunter accessibility, provide travel corridors for pointing dogs, manage vegetation succession, among other benefits. Managers typically create hunting paths in a grid pattern at 30 ft spacing resulting in approximately 35% of vegetation removed prior to hunting season. However, the optimal spacing for paths is unknown and some concern exists over the presence of paths in general as they may facilitate predation. Our objectives were to determine how different densities of paths (i.e., reduced cover and increased edge) impacted northern bobwhite survival, quantify the costs per hectare of paths, and determine hunter satisfaction. We developed two path treatments (30 ft and 90 ft spacing) and a control (no paths) on Tall Timbers Research Station in Leon County, Florida. We radio-tagged a subset of northern bobwhites (n = 150), equally distributed within each treatment, and monitored survival in each treatment using radio-telemetry during the non-breeding season (October through April) in 2013-2016. We used Burnham’s joint model within program MARK to compare survival of radio-tagged bobwhites among treatment groups. We analyzed data collected from a hand-held global positioning system used to delineate paths during creation to compute implementation cost. Hunter satisfaction was assessed using a pre- and post-hunt survey. Optimization will be used to determine which treatment achieves the greatest utility under current management objectives. Results of this research will provide managers information to make informed decisions about the implementation of hunting paths under various management scenarios

Behavioral State-Specific Northern Bobwhite Chick Resource Selection

Determining resource selection rates for all life stages of a species is critical to enable a holistic management approach that focuses on bolstering populations across all life stages. Moreover, tying these selection rates to specific life history needs (e.g., foraging, roosting, and loafing) can provide valuable information to guide management practices. Northern bobwhite (Colinus virginianus; hereafter, bobwhite), a gallinaceous species of North America, has experienced steady population declines throughout much of its range over the last 50 years. Although the species has been well studied, chick ecology is still relatively unknown. We studied bobwhite chick resource selection on a private property in Brunswick County, North Carolina, USA to better understand daily and within home range selection. The site was managed intensively for bobwhite using prescribed fire, seasonal mowing and disking, mesomammal control, and supplemental feeding. We radio-tagged 156 chicks 11–15 days of age from 29 unique broods and collected location data for nocturnal roost sites, daily movement tracks, and diurnal use sites during a 2-year span. We had selection models for 3 behaviors: roosting, foraging, and general movements within home range (third-order). All models were mixed-effects conditional logistic regression models under a Bayesian framework. We determined foraging behavior using a straightness index for daily track segments; more tortuous segments were designated as foraging locations. Upland pine stands (burned and unburned) were selected for foraging and roosting. Chicks were more likely to select areas closer to feedlines for roosting, foraging, and diurnal habitat; however, selection of these areas decreased as birds grew older. Chicks avoided fallow fields and hardwood drains or Carolina bays as roost site locations yet selected them as foraging habitat. Roosting birds avoided fallow fields as roost sites and instead selected areas adjacent to them. Probability of use for diurnal and roosting habitat decreased as distance to fallow fields increased. Our study results shed light on how circadian habitat use can vary and illustrate that one specific land cover may not provide ideal diurnal and nocturnal habitat for bobwhite chicks. The results also reinforce the need to provide resources that meet diurnal and nocturnal requirements within biologically reasonable distances from each other

Acoustic response of a feeding system to high-frequency transverse acoustic field

International audienceThe acoustic coupling between the injection system and the acoustic fluctuations in liquid rocket engine combustion chambers is an important issue in the understanding of the thermo-acoustic instability phenomenon. This paper presents results of a large parametric investigation of a two-phase injection system acoustic response, to the excitation produced by a high-amplitude transverse acoustic field forced into a main resonant cavity. Two domes, one for the gas and one for the liquid, were expressly designed to feed three identical coaxial injectors. Characterization of domes internal mode shapes were performed by measuring pressure signals at different locations in the domes. Experimental mode shapes showed good agreement with those predicted by numerical simulations. Acoustic pressure amplitudes up to 17% of the the one induced in the main cavity can be found in both gas and liquid dome. The maximum acoustic response is observed in a configuration in which acoustic boundary conditions does not correspond to the maximum injection system solicitation conditions

Vasectomy under local anaesthesia performed free of charge as a family planning service: Complications and results

Objective. To evaluate the safety and efficacy of vasectomy performed under local anaesthesia by junior doctors at a secondary level hospital as part of a free family planning service.Method. Men requesting vasectomy were counselled and given written instructions to use alternative contraception until two semen analyses 3 and 4 months after vasectomy had confirmed azoospermia. Bilateral vasectomy was performed as an outpatient procedure under local anaesthesia by junior urology registrars. Statistical analysis was performed using the Mann-Whitney, Kruskal-Wallis, Fisher’s exact orSpearman’s rank correlation tests as appropriate.Results. Between January 2004 and December 2005, 479 men underwent vasectomy at Karl Bremer Hospital, Western Cape, South Africa; their average age was 36.1 (range 21 - 66) years, they had a median of 2 (range 0 - 10) children, and only 19% had 4 or more children. The average operation time was 15.5 (range 5 - 53) minutes. Complications occurred in 12.9%; these were pain (7.3%), swelling (5.4%), haematoma (1.3%), sepsis (1%), difficulty locating the vas (1%), vasovagal episode (0.6%), bleeding (0.6%), wound rupture (0.4%) and dysuria (0.2%) (some men had more than one complication). Of the men 63.3% returned for one semen analysis and 17.5% for a second. The vasectomy failure rate ranged from 0.4%(sperm persisting >365 days after vasectomy) to 2.3% (sperm seen >180 days after vasectomy and/or in the second semen specimen). No pregnancies were reported. The complication (5.6%) and failure rates (0%) were lowest for the registrar who had performed the smallest number of vasectomies and whose average operation time was longest. Comparing the first one-third of procedures performed by each of the doctors with the last one-third, there was a significant decrease inaverage operating times but not in complication rates.Conclusions. Vasectomy can be performed safely and effectively by junior doctors as an outpatient procedure under local anaesthesia, and should be actively promoted in South Africa as a safe and effective form of male contraception

The Effect of Age-At-Release on Survival of Adoptive Parent-Reared Bobwhite Chicks

Translocation of wild northern bobwhites (Colinus virginianus) to restore local populations is a viable conservation tool under some scenarios; however, the supply of wild bobwhites is limited. Bobwhites can be artificially propagated, as an alternative to translocation, using methods that mimic natural brood-rearing. The parent-rearing adoptive process (PRAP) uses wild-strain bobwhite adults to brood and foster newly hatched wild-strain chicks in outdoor aviaries that emulate a natural environment. Adoptive parent-reared bobwhites have higher survival rates than artificially-reared bobwhites but only a single age-of-release (i.e., 6-weeks) has been tested. We tested the effect of age-at-release (3, 6, and 9-weeks) on adoptive parent-reared chicks released on the same date in Hanna Hammock of Tall Timbers Research Station. All chicks were marked with patagial wing tags and a subset of the group received radio transmitters. The 3-week-olds (n = 25) received suture-style transmitters and 6-week-olds (n = 30) and 9-week-olds (n = 30) received necklace-style transmitters. Our adoptive parent-reared chicks had low survival rates over 3 months post-release, the 9-week age group had the highest overall survival rates which could portend that increased physiological development may aid in increasing the survivability of adoptive parent-reared bobwhites. The low survival rates across all 3 age classes calls into question the efficacy of the PRAP as a bobwhite restoration method. Our results do suggest that additional modifications to release age (\u3e 9-weeks) should be explored along with further modifications to the PRAP. Additional modifications include incorporating predator avoidance training, altering release dates, and changing nutritional regimes. These results should caution the bobwhite community to remain suspect when deriving conclusions about the PRAP until all process modifications have been fully evaluated by scientific research

Using First Passage Time Analysis to Identify Foraging Patterns of the Northern Bobwhite

Patterns in movement data can reveal important information relating environmental variables to behavioral mechanisms. First passage time analysis (hereafter; FPT) can be used to quantify the spatial and temporal variation in movements by identifying areas of restricted search behavior based on measuring residence time in an area. It is applicable in studies of foraging ecology and habitat selection because it can empirically quantify behavioral decisions without any a priori assumptions of habitat availability. Furthermore, FPT analysis is simple to implement and interpret; however, the technique has yet to be applied to the northern bobwhite (Colinus virginianus, hereafter bobwhite) because telemetry locations in short (e.g., 30 min) successive time intervals are needed. Our primary objective was to better understand patterns in foraging behavior of bobwhites as it relates to habitat use and improve management. Our secondary objective was to test the efficiency of using FPT analysis on telemetry data collected at different time intervals. Bobwhites were captured during the fall of 2013 and 2014 on a private plantation in South Carolina and fitted with very high frequency (VHF) transmitters (n = 143 and n = 148, respectively). We located coveys at 1 hour (2013) and 30 (2014) minute time intervals during daylight. Bobwhites concentrated their searching efforts to a few hours pre-dusk. Search efforts were proximal to supplemental food sources, with some intra-seasonal variation. Advances in global positioning system (GPS) technology will likely increase opportunities for collecting fine-scale movement data for bobwhites. Understanding techniques such as FPT analysis will enhance our knowledge of northern bobwhite ecology and management

Response of coaxial air-assisted liquid jets in an acoustic field: atomization and droplets clustering

International audienceHigh-frequency combustion instabilities have been proven to be extremely harmful to liquid rocket engine operation , even leading to the destruction of the combustion chamber. The coupling between acoustic field and combustion heat release rate in the combustion chamber is considered as the driving phenomenon. Experiments have shown that intense acoustic field can deeply affect atomization process thereby causing a non-uniform heat release distribution which can couple with the resonant mode shapes of the combustion chamber and consequently trigger or sustain combustion instability. The effects of acoustic acting on atomization of coaxial air-assisted liquid jets have been investigated experimentally and results are presented in this paper. The experimental setup is composed of three coaxial injectors installed on the roof of a semi-open resonant cavity provided with 4 compression drivers. An acoustic field corresponding to the 2 nd transverse mode of the cavity is forced into that at a frequency of 1 kHz. Acoustic levels up to 174 dB are produced. High speed visualizations are performed in order to observe the response of the jet to the acoustic perturbations. In the case of low Weber numbers (We < 30) the jet can be considered as cylindrical and depending on the position of the injector with respect to the acoustic axis different responses can be observed. If the injector is placed in correspondence of the velocity antinode the jet is flattened into a liquid sheet perpendicular to the acoustic axis, if the injector is located in correspondence of an intensity antinode the jet is deviated toward the velocity antinode. Combined response can be observed at intermediate positions. For higher Weber numbers the jet is no more cylindrical and a spray is formed, characterized by with a certain spray angle. Such a spray is can still be affected by the acoustics but it is not always possible to get evidence of this from observation of raw images. To quantify these effects, image analyses have been carried-out to determine how spatial distributions of droplets are affected by acoustics. Results are presented for Weber numbers ranging from 30 to 1500, with and without acoustic. Clustering of droplets is shown as well as improvement of atomization process