Response properties of neurons in the inferior colliculus of the monaurally deafened ferret to acoustic stimulation of the intact ear

Response properties of neurons in the central nucleus of the inferior colliculus (ICC) were investigated after unilateral cochlear removal at various ages during infancy. Nineteen ferrets had the right cochlea surgically ablated, either in adulthood or on postnatal day (P) 5, 25, or 40, 3-18 mo before recording. Adult ablations were made on the same day as ("acute," n = 3), or 2-3 mo before ("chronic," n = 3), recording. Two ferrets were left binaurally intact. Single-unit (n = 702) and multiunit (n = 1,819) recordings were made in the ICC of barbiturate-anesthetized ferrets ipsilateral (all ages) or contralateral (P5 and acute adult only) to the intact ear. In binaurally intact animals, tonal stimulation of the contralateral ear evoked excitatory activity at the majority (94%) of recording loci, whereas stimulation of the ipsilateral ear evoked activity at only 33% of recording loci. In acutely ablated animals, the majority of contralateral (90%) and ipsilateral (70%) loci were excited by tonal stimulation of the intact ear. In chronically ablated animals, 80-90% of loci were excited by ipsilateral stimulation. Single-unit thresholds were generally higher for low-best frequency (BF) than for high-BF units, and higher in the ipsilateral than in the contralateral ICC. Analysis of covariance showed highly significant differences between all of the ipsilateral and contralateral groups, but no effects of age at ablation or survival time following ablation, other than that the group ablated at P25 had higher mean ipsilateral thresholds than the groups ablated at P5 or, acutely, in adulthood. Cochlear ablation at P5, 25, or 40 resulted in a significant increase in dynamic ranges of ipsilateral ICC unit rate-intensity functions relative to acutely ablated animals. Dynamic ranges of units in the contralateral ICC of P5-ablated ferrets were also significantly increased compared with those of acutely ablated animals. Cochlear ablation at P5, 25, or 40 resulted in a significant increase in single-unit spontaneous discharge rates in the ICC ipsilateral but not contralateral (P5 only) to the intact ear. These data show that unilateral cochlear removal in adult ferrets leads to a rapid and dramatic increase in the proportion of neurons in the ICC ipsilateral to the intact ear that is excited by acoustic stimulation of that ear. In addition, the data confirm that, in ferrets, cochlear removal in infancy leads to a further increase in responsiveness of individual neurons in the ipsilateral ICC. Finally, the data show that responses in the ICC contralateral to the intact ear are largely but not completely unchanged by unilateral cochlear removal.     

Reliability of using random urine samples for "spot" determination of fractional excretion of electrolytes in cats

OBJECTIVE: To determine whether the "spot" method of determining fractional excretion (FE) of electrolytes in cats is accurate. ANIMALS: 5 clinically normal young adult female cats. PROCEDURE: Cats were acclimated to metabolism cages, and 2 consecutive 72-hour collections of urine were made to determine FE of total calcium, potassium, total magnesium, sodium, and phosphorus by conventional methods, using endogenous creatinine clearance as an estimate of glomerular filtration rate. During collections, small samples of urine were obtained by cystocentesis at 8 AM, 3 PM, and 9 PM for determination of FE of the electrolytes by use of the "spot" method. RESULTS: Values from "spot" determinations were highly variable, compared with 72-hour values, with a high percentage falling outside the range of mean +/- 2 SD for 72-hour FE values. CONCLUSIONS AND CLINICAL RELEVANCE: The "spot" method for determining FE is not precise, and if used, caution and judgement should be exercised in interpretation of the results.     

Electromagnetic Design of a Magnetically Coupled Spatial Power Combiner

The design of a two-dimensional spatial beam-combining network employing a parallel-plate superconducting waveguide filled with a monocrystalline silicon dielectric substrate is presented. This component uses arrays of magnetically coupled antenna elements to achieve high coupling efficiency and full sampling of the intensity distribution while avoiding diffractive losses in the multimode waveguide region. These attributes enable the structure’s use in realizing compact far-infrared spectrometers for astrophysical and instrumentation applications. If unterminated, reflections within a finite-sized spatial beam combiner can potentially lead to spurious couplings between elements. A planar meta-material electromagnetic absorber is implemented to control this response within the device. This broadband termination absorbs greater than 0.99 of the power over the 1.7:1 operational band at angles ranging from normal to near-parallel incidence. The design approach, simulations and applications of the spatial power combiner and meta-material termination structure are presented.     

Handling the complexities of real-life job shops when implementing workload control: a decision framework and case study

The workload control literature highlights the importance of balancing the shop floor workload, but also acknowledges that this can conflict with processing the most urgent orders – hence, there is a trade-off. In practice, shops contain many complexities, e.g. simultaneous batching and sequence-dependent set-up times that may conflict with processing the most urgent orders and require other solutions than workload balancing to avoid capacity losses. This adds to the trade-off dilemma, which traditionally only considers timing and balancing. This paper develops a framework that determines whether to address a complexity through order release or dispatching. It comprises two dimensions: (i) the typical position of a complexity in the routing of an order and (ii) the criticality of the complexity. A case study is presented, which demonstrates the framework’s utility and illustrates the development of specific solutions designed to handle the complexities. Most complexities present in the case require handling at the order release stage. The challenges of handling multiple complexities at this decision level are evaluated. Finally, the implications for managers and future research are outlined.     

Development of role-related minimum cardiorespiratory fitness standards for firefighters and commanders

A minimum cardiorespiratory fitness standard was derived for firefighters following a metabolic demands analysis. Design and minimal acceptable performance of generic firefighting task simulations (i.e. hose running, casualty evacuation, stair climb, equipment carry, wild-land fire) were endorsed by a panel of operationally experienced experts. Sixty-two UK firefighters completed these tasks wearing a standard protective firefighting ensemble while being monitored for peak steady-state metabolic demand and cardiovascular strain. Four tasks, endorsed as valid operational simulations by ≥90% of participants (excluding wild-land fire; 84%), were deemed to be a sufficiently valid and reliable basis for a fitness standard. These tasks elicited an average peak steady-state metabolic cost of 38.1 ± 7.8 ml kg^?1 min^?1. It is estimated that healthy adults can sustain the total duration of these tasks (~16 min) at ≤90% maximum oxygen uptake and a cardiorespiratory fitness standard of ≥42.3 ml kg^?1 min^?1 would be required to sustain work.

Practitioner Summary: A cardiorespiratory fitness standard for firefighters of ≥42.3 ml kg^?1 min^?1 was derived from monitoring minimum acceptable performance of essential tasks. This study supports the implementation of a routine assessment of this fitness standard for all UK operational firefighters, to ensure safe physical preparedness for occupational performance.     

Measles inclusion-body encephalitis in a child with treated acute lymphoblastic leukaemia

A child with acute lymphoblastic leukaemia, being treated in the UKALL II Trial, had while in remission an attack of measles and made a normal recovery. Four months later she developed an acute encephalopathy and died within two weeks. The brain showed mild inflammatory features and widespread inclusion bodies in neurones and glial cells. Immunofluorescence proved an infection with measles virus. Similar cases have been called SSPE; reasons are given for preferring the term "measles inclusion-body encephalitis".     

Photochromism of an anticonvulsant, 1-diphenylmethyl-4-(6-methyl-2-pyridylmethylene-amino) piperazine, in the solid state

The light-induced color change of 1-diphenylmethyl-4-(6-methyl-2-pyridylmethyleneamino) piperazine in the solid state was investigated. Light in the 420-700-nm visible region had no effect. Elevated temperature, dissolution, or prolonged storage in the dark at room temperatures restored the intrinsic color of the compound. IR, UV (solution), NMR, differential scanning calorimetry, and GC methods showed no detectable difference between the long wave-length UV light-exposed (yellow) and unexposed (colorless) samples of the pure compound. Long wavelength UV light exposure studies with several substituted piperazine analogs revealed a structure-activity requirement for the color conversion process. The data indicated that the transformation process from colorless (or faint yellow) to bright yellow is photochromism (phototropy) and is dependent on the intensity of the "action spectrum" in the 300-400-nm region. Studies in the solid state showed that heat-induced fading of the color followed apparent zero-order kinetics. The energy of activation, Eb, for the photochromic conversion process from the metastable (yellow) to the stable (colorless) state was estimated to be about 19 kcal/mole.     

Forearm fractures in children: pitfalls and complications

Five hundred fourty-seven consecutive forearm fractures in children were studied, with special emphasis on complications encountered. The most important apparent conclusion reached from this study is that greenstick and complete fractures are different, and that some of the pitfalls and complications seen following these injuries can be avoided if different methods of reduction are used for each. Greenstick fractures should be reduced by manipulating them into the correct proper plane of rotation; i.e., maximum pronation for distal third fractures, neutral for middle third fractures, and supination for proximal third fractures. Application of this familiar "rule of thirds" to complete fractures, however, may result in ratational deformity at the fracture site. Completer fractures should be reduced by finger trap traction, allowing the fracture to seek its own level of rotation. Several other observations were also noted. Angulation into radial deviation was found to remodel and equally as well as volar angulation, and remodeling may contine for as long as two years after injury. Growth disturbance following fractures through the distal radial epiphyseal plate is uncommon, but premature closure of the epiphysis did occur in one patient with a typical Type II fracture. Six concomitant nerve injuries were seen; all recovered spontaneously within 3 weeks.     

Wave Phenomena in Low Angle Peeling

The angular dependence of peeling has been investigated over a wide range of peel angles for a rubber strip peeled from glass. At low peel angles the peel front becomes “V”-shaped, wave phenomena are often observed and the peel energy can increase by an order of magnitude or more. A tentative theory, which appears to give the correct magnitude in a worked example, is advanced to account for the energy increase. The influence of factors such as electrostatic charge, deformation and rate on the observed phenomena are discussed.     

Organophosphite transformations in flexible PVC formulations

Organophosphites are a versatile component of liquid PVC heat stabilizers and stabilize PVC through a variety of mechanisms. Organophosphites can decompose peroxides, replace labile chlorines on the PVC backbone, scavenge HCl (via the Arbuzov rearrangement), complex Lewis acids, and add to double bonds. This paper attempts to identify the relative contributions of these mechanisms in both model systems and flexible PVC formulations. J. Vinyl Addit. Technol. 10:99–103, 2004. © 2004 Society of Plastics Engineers.