Ulnar Superficialis Slip Resection versus Radial Superficialis Slip Resection: A Biomechanical Pilot Study

Background: There are numerous clinical scenarios during which the surgeon contemplates whether the radial or ulnar slip of the flexor digitorum superficialis (FDS) should be sacrificed. To date no study has assessed the point of failure of each one of the FDS slips in each digit, aiding the avid surgeon in deciding which slip to sacrifice. Methods: A total of 41 digits were assessed, each digit was dissected, and a specimen containing the denuded bone of the middle phalanx with the attachments of the ulnar and radial FDS slips was obtained. An Instron 4502 device was utilized to biomechanically assess the point of failure of each slip of each digit. Results: There was no statistical difference between ulnar and radial slip point of failure when compared across all digits and subjects. There was no statistical difference between male and female subject’s specimens. The point of failure was higher in the ulnar slips of the second and third digits, whereas the point of failure was higher in the radial slips of the fourth and fifth digits. Conclusions: Sacrifice of a FDS slip may cause loss of grip strength. In several clinical scenarios one may be faced with the dilemma which FDS slip to sacrifice. Our findings show this is not an arbitrary choice. Hand surgeons should keep our findings in mind when deciding which slip to sacrifice, in effort to preserve function and strength in the injured hand.

Verification of a method for determining the limit pressure peak in a mechanical continuously variable transmission

This research concerns the continuously variable transmission that is to be used in a hybrid drivetrain with a mechanical energy accumulator as a secondary energy source. The purpose of this research is to verify the method of determining the pressure surge which ensures a fast but safe ratio change, from the perspective of the belt slip point of a continuously variable transmission. The obtained results allowed to decide on the design of a more extensive test bench enabling simulation of the load of a continuously variable transmission resulting from the acceleration and braking of the car's mass. In addition, the test results confirmed the possibility of regulating the pressures in two actuators to change the ratio and increase the speed of this change.

Effect of sex and dietary treatment on the composition and rheological properties of dry-cured ham subcutaneous fat

The effect of sex, dietary fat source (lard vs palm oil), and glycerol inclusion in fattening diet on the composition, fatty acid distribution within the triglyceride (TAG) and slip point and textural parameters was studied on dry-cured hams subcutaneous fat. A marked effect of sex on saturated fatty acids (SFA) percentage was found with barrows showing higher values than gilts. No effect of dietary fat source on subcutaneous SFA or polyunsaturated fatty acids (PUFA) was observed. Dietary glycerol increased monounsaturated fatty acids and decreased total PUFA in subcutaneous fat. Besides, the possibility of altering fatty acid composition at the 2-position of the TAG by dietary intervention during the fattening phase is very limited. Partial restructuration was observed in external positions of the TAG. All these changes affected slip point and textural parameters. An increase of hardness when palm oil was used as dietary fat and a decrease in all textural parameters values when glycerol was included were observed.

Computations of the Numerical Solutions of Higher Class of Navier-Stokes Equations: 2D Newtonian Fluid Flow

This paper presents formulations, computations, investigations and consequences of the various aspects of the numerical solutions of classes C00 and C11 of the two dimensional Navier-Stokes equations in primitive variables u, v, p, τxx, τxy and τyy for incompressible, isothermal and laminar Newtonian fluid flows using p-version Least Squares Finite Element Formulations (LSFEF). The stick-slip problem is used as a model problem in all investigations since this model problem is typical of many other flow situations like contraction, expansion etc. The major thrust of the work presented is to attempt to resolve the local behavior of the solutions in the immediate vicinity of the stick-slip point. The investigations reveal the following: a) The manner in which the stresses are non-dimensionalized in the governing differential equations (GDEs) influences the performance of the iterative procedure of solving non-linear algebraic equations and thus, computational efficiency. b) Solutions of the class C00 are always the wrong class of solutions and thus are always spurious. c) In the flow domains, containing sharp gradients of dependent variables, conservation of mass is difficult to achieve specially at lower p-levels. d) C11 solutions of the Navier-Stokes equations are in conformity with the continuity considerations in the GDEs. e) An augmented form of the Navier-Stokes equations is proposed that always ensures conservation of mass regardless of mesh, p-levels and the nature of the solution gradients. This approach yields the most desired class of C11 solutions. f) It is mathematically established and numerically demonstrated using stick-slip problem that τij are in fact zero at the stick-slip point and the peak values of τxx and τyy must occur, and in fact do, past the stick-slip point in the free field and that peak values of τxy must occur before the stick-slip point on the no-slip boundary. Thus, there is no singularity of τij in the stick-slip problem at the stick-slip point. A significant finding is that imposition of symmetry boundary condition (necessary based on physics) at the stick-slip point even in C11 interpolations is not possible without deteriorating τij behavior in the vicinity of the stick-slip point. However, with the boundary condition, the peak of τxy does occur before the stick-slip point, while the locations of τxx and τyy remain past the stick-slip point in the free field. h) A significant feature of our research work is that we utilize straightforward p-version LSFEF with C00 and C11 type interpolation without linearizing GDEs and that SUPG, SUPG/DC, SUPG/DC/LS operators are neither needed nor used. All numerical studies are conducted and presented using three different meshes (progressively refined and graded) for two different velocities (0.01 and 100 m/s).

Grip force adjustments evoked by load force perturbations of a grasped object

1. Brief increases or decreases in vertical load force were applied to an object held between the thumb and finger. Grip force increases occurred consistently from 60 to 90 ms after onset of the load force increase. These responses did not adapt and were typically from 100 to 200 ms in duration. Reductions in object load force yielded rapid reductions in grip force at latencies comparable to those for load increases. 2. Response magnitude was proportional to the size or velocity of the load force increment, but did not vary with the level of the preexisting grip force. Thus these responses did not maintain the grip force at a specified level above the object's slip point. 3. Grip force responses were abolished or substantially reduced when loads were delivered directly to the hand rather than to the object. In contrast, force responses were not always abolished upon anesthetization of the thumb and finger. These results are discussed in relation to the role of cutaneous mechano-receptors of the digital pulps and proprioceptors of the arm and hand for providing necessary afferent information utilized in load-related grip force modulation. 4. Rapid and automatic grip force adjustments to load force variations may contribute importantly to grasp tasks in which the load forces vary dynamically and without complete predictability, such as in the manipulation of tools or objects that contact the environment.