Improved Hodgkin-Huxley type model for neural action potentials.

The simple Goldman-Hodgkin-Katz model for resting-state membrane potentials has been generalized to provide a new nonlinear theoretical model for action potentials in perfused axons. Our minimalistic model appeals naturally to physically based electrodiffusion principles to describe electric-current densities inside sodium and potassium-ion channels whereas the 1952 Hodgkin-Huxley model describes such current densities in an ad hoc way. Although the two models share similar schemes for the kinetics of ion-channel gating, our relaxation times for channel gating are simpler, being independent of membrane potential.

Evaluation of Protective Equipment Used Among Motorbike Riders.

Introduction: This study compared outcomes between patients injured at a motorbike track, which requires riders to follow safety equipment guidelines, and those involved in recreational riding where safety equipment usage is voluntary.

Methods: A retrospective review was conducted of all patients presenting with motorbike-related injuries at an American College of Surgeons verified level-I trauma center between January 1, 2009 and December 31, 2013. Data collected included demographics, injury details, safety equipment use, hospitalization details, and discharge disposition.

Repeat head imaging in blunt pediatric trauma patients: Is it necessary?

Background: Children with confirmed brain injury usually undergo follow-up computed tomography (CT) scan of the head within 24 hours of admission. To date, no evidence exists to validate the diagnostic or therapeutic value of these repeat CTs. The purpose of this study was to (1) evaluate progression of traumatic brain injuries, (2) determine if routine repeat imaging changes management, and (3) compare the efficacy of recognizing worsening hemorrhage with serial neurological examination versus repeat imaging.

Pediatric trauma system models: do systems using adult trauma surgeons exclusively compare favorably with those using pediatric surgeons after initial resuscitation with an adult trauma surgeon?

Background: A shortage of pediatric surgeons exists. The purpose of this study was to evaluate pediatric outcomes using pediatric surgeons vs adult trauma surgeons.

Methods: A review was conducted at 2 level II pediatric trauma centers.

Evaluation of chest tube administration of tissue plasminogen activator to treat retained hemothorax.

Background: When retained hemothorax occurs, video-assisted thoracoscopy or thoracotomy is performed, but recently, tissue plasminogen activator (tPA) has been used. This study evaluated intrapleural tPA use for retained traumatic hemothoraces.

Methods: A retrospective review was conducted of trauma patients treated with intrapleural tPA for retained hemothorax.

On the nature of liquid junction and membrane potentials.

Whenever a spatially inhomogeneous electrolyte, composed of ions with different mobilities, is allowed to diffuse, charge separation and an electric potential difference is created. Such potential differences across very thin membranes (e.g.

Hydrodynamic control of the interface between two liquids flowing through a horizontal or vertical microchannel.

We derive a Fourier expansion for estimating laminar hydrodynamic spreading when two immiscible liquids flow steadily, side by side, at low Reynolds number, in a horizontal microchannel of rectangular cross-section. When the aspect ratio of the height of the channel to its width is small this expansion can be truncated after a couple of terms and solved to yield the steady-state position of the boundary in terms of the constant volumetric flow rates, the aspect ratio and the viscosities of the two liquids. Our formula shows that we can control the location of the liquid boundary at the outlet of the microchannel by adjusting the relative volumetric flow rates of the two inlet streams.

Convective Sedimentation of Colloidal Particles in a Bowl.

A physical model, which regards a colloidal dispersion as a single fluid continuum, is used to investigate cellular convection accompanying gravitational sedimentation in a hemispherical bowl with a thin cylindrical shaft along its vertical axis of symmetry. We have adapted the stream-function-vorticity form of the Navier-Stokes equations to describe momentum conservation in axially symmetric containers. These hydrodynamic equations have been coupled to the mass balance equation for binary hydrodynamic diffusion in the presence of a vertical gravitational field.

Spontaneous Thermal Convection in the Vicinity of Electrolyte/Water Interfaces.

We present theoretical evidence for transient roll-cell convection induced in the vicinity of freshly prepared electrolyte/water interfaces. The mechanism relies on a hitherto unrecognized type of double-diffusive convection. Electrolyte diffusion down the strong concentration gradient at the interface produces local heating just below the interface as the electrolyte becomes more dilute.

Rehabilitation of lower limb traumatic amputees: the Sandy Gall Afghanistan Appeal's experience.

Physical rehabilitation after lower limb traumatic amputation due to acts of war has not yet been investigated. It has been shown that patients suffering non-war injuries rehabilitate well. This study shows that despite the difficult circumstances and limited resources available in an area of conflict, good rehabilitation of war victims is possible.

Early failure of titanium alloy femoral components: a quantitative radiological analysis of osteolytic and granulomatous change.

Shot blasted titanium alloy femoral components with a coarse finish were withdrawn from use in 1987 following reports of early component failure. We reviewed all coarse titanium femoral stems used in primary total hip arthroplasty in our institution between 1985 and 1987 and compared them to a similar stem made of vitallium which was also used over the same period. We found that, at an average of 5.

The Guildford elbow.

A new unconstrained elbow replacement is described and the results of 44 primary and 5 revision operations assessed. A high incidence of pain relief (82%) and functional improvement (73%) was achieved. However 23% of primary replacements later underwent loosening as assessed radiologically and 12% have undergone revision for pain.

Cubital bursitis.

We describe two cases of bursitis at the insertion of the biceps tendon. They presented as swellings in the cubital fossa with symptoms of median nerve irritation. The aetiology was probably mechanical trauma; both patients were cured by operation.

Osteomyelitis in a general hospital. A five-year study showing an increase in subacute osteomyelitis.

We have reviewed 60 patients with primary bone infections; 21 of these (35%) had subacute osteomyelitis, a figure which supports other recent observations that this variant of bone infection is becoming more widespread. In this group open culture and biopsy were necessary in order to exclude bony malignancy, and a raised erythrocyte sedimentation rate proved a useful diagnostic aid. All the patients with acute osteomyelitis or with vertebral infection responded to primary treatment, but five of those with subacute osteomyelitis had recurrences.