Posterior Cervical Spine Crisscross Fixation: Biomechanical Evaluation

Background Biomechanical/anatomic limitations may limit the successful implantation, maintenance, and risk acceptance of posterior cervical plate/rod fixation for one stage decompression-fusion. A method of posterior fixation (crisscross) that resolves biomechanical deficiencies of previous facet wiring techniques and not reliant upon screw implantation has been devised. The biomechanical performance of the new method of facet fixation was compared to the traditional lateral mass plate/screw fixation method. Methods Thirteen human cadaver spine segments (C2-T1) were tested under flexion-compression loading and four were evaluated additionally under pure-moment load. Preparations were evaluated in a sequence of surgical alterations with intact, laminectomy, lateral mass plate/screw fixation, and crisscross facet fixation using forces, displacements and kinematics. Findings Combined loading demonstrated significantly lower bending stiffness (p \u3c 0.05) between laminectomy compared to crisscross and lateral mass plate/screw preparations. Crisscross fixation showed a comparative tendency for increased stiffness. The increased overall motion induced by laminectomy was resolved by both fixation techniques, with crisscross fixation demonstrating a comparatively more uniform change in segmental motions. Interpretation The crisscross technique of facet fixation offers immediate mechanical stability with resolution of increased flexural rotations induced by multi-level laminectomy. Many of the anatomic limitations and potentially deleterious variables that may be associated with multi-level screw fixation are not associated with facet wire passage, and the subsequent fixation using a pattern of wire connection crossing each facet joint exhibits a comparatively more uniform load distribution. Crisscross wire fixation is a valuable addition to the surgical armamentarium for extensive posterior cervical single-stage decompression-fixation

A Proton Magnetic Resonance and Infrared Study of Colemanite and lnyoite

A proton magnetic resonance and IR investigation of colemanite, Ca B30 4 (0H) 3 • H 20 and inyoite, CaBa0a(OH) 5 • 4H20, is in agreement with the X-ray crystal structure analysist,2 concerning these two newly proposed formulae. It is confirmed that at room temperature there is a dynamic distribution of proton sites in the ferroelectric colem anite, while there is no such effect in inyoite. Ther~ are two second moment transitions in p. m. r. spectra of colemanite. The one at about -nooc is due to the onset of reorientation of water molecules. The second one at T c is discussed in terms of a dyna mic m odel involving a change from a symmetric double well potential for the moving protons into an asymmetric one below Tc

Prototipe Aplikasi Materi Promosi Ritel Merchandise Bebasis Web (Studi Kasus PT. Matahari Putra Prima, Tbk)

Dalam dunia binis ritel yang semakin berkembang, pelaku USAha di tuntut untuk dapat bertumbuh disituasi yang tidak pasti saat ini, kegiatan bisnis yang stabil akan membuat USAha terus bergerak dan dapat memberikan pertumbuhan yang baik pada Perusahaan. Salah sayu hal yang paling memberikan pengaruh pada bisnis ritel adalah analisa pasar, persaingan harga dan kegiatan promosi yang di lakukan oleh para pengusaha ritel. Promosi merupakan cara yang digunakan untuk menginformasikan dan membujuk konsumen tentang produk atau jasa yang baru pada Perusahaan melalui media cetak, penjualan pribadi, promosi penjualan. Hal itu membuat pelaku bisnis ritel banyak mengunakan media promosi untuk meningkatkan penjualan dan untuk bersaing dengan kompetitor lainnya. Kegiatan promosi dapat memberikan efek positif yang berpengaruh pada cara pandang konumen akan sebuah Perusahaan ritel. Penelitian ini dilakukan untuk membantu Merchandiser dalam memperoleh informasi tentetang kegiatan promosi yang dilakukan oleh kompetitor ritel yang belum tersedia saat ini dan agar dapat menganalisa rencana promosi yang bagimana sehingga dapat diambil untuk memberikan persaingan harga dan dapat membujuk konsumen untuk berbelanja

Biomechanical Tolerance of Whole Lumbar Spines in Straightened Posture Subjected to Axial Acceleration

Quantification of biomechanical tolerance is necessary for injury prediction and protection of vehicular occupants. This study experimentally quantified lumbar spine axial tolerance during accelerative environments simulating a variety of military and civilian scenarios. Intact human lumbar spines (T12‐L5) were dynamically loaded using a custom‐built drop tower. Twenty‐three specimens were tested at sub‐failure and failure levels consisting of peak axial forces between 2.6 and 7.9 kN and corresponding peak accelerations between 7 and 57 g. Military aircraft ejection and helicopter crashes fall within these high axial acceleration ranges. Testing was stopped following injury detection. Both peak force and acceleration were significant (p \u3c 0.0001) injury predictors. Injury probability curves using parametric survival analysis were created for peak acceleration and peak force. Fifty‐percent probability of injury (95%CI) for force and acceleration were 4.5 (3.9–5.2 kN), and 16 (13–19 g). A majority of injuries affected the L1 spinal level. Peak axial forces and accelerations were greater for specimens that sustained multiple injuries or injuries at L2–L5 spinal levels. In general, force‐based tolerance was consistent with previous shorter‐segment lumbar spine testing (3–5 vertebrae), although studies incorporating isolated vertebral bodies reported higher tolerance attributable to a different injury mechanism involving structural failure of the cortical shell. This study identified novel outcomes with regard to injury patterns, wherein more violent exposures produced more injuries in the caudal lumbar spine. This caudal migration was likely attributable to increased injury tolerance at lower lumbar spinal levels and a faster inertial mass recruitment process for high rate load application. Published 2017. This article is a U.S. Government work and is in the public domain in the USA

Electron Paramagnetic Resonance in I-Irradiated Ferroelectric LiH3 (Seo;)2

Single crystals of LiH3(Se03) 2 were grown from water solution. The samples were exposed at room temperature to gamma radiation from a Co60 source and received doses of 106 r