Force Push Research Articles

Poster 28: The Effect of Genital Tract Trauma on Pelvic Floor Function After Childbirth

OBJECTIVE: The objective of this study was to describe the impact of genital tract trauma on the prevalence of perineal pain, urinary (UI) and anal incontinence (AI), and sexual function in a low-risk cohort of women after vaginal birth. METHODS: In this prospective cohort study, women completed validated questionnaires at discharge, 6 weeks and 3 months postpartum. Questionnaires included the Modified McGill pain scale, Incontinence Impact Questionnaire (IIQ-7), Fecal Incontinence Score (FIS), and Intimate Relationship Scale (IRS). Intrapartum events were recorded and trauma was mapped to site (anterior or perineal) and severity (major or minor). Chi-squared analyses were used to compare subgroups. Significance was set at P<0.05. RESULTS: Five hundred thirteen women participated with follow-up rates of 96% postpartum day 1, 63% at 6 weeks, and 57% at 3 months. Mean age was 24.8 ± 5.2 years and 40% were nulliparous. Less than 1% of women underwent episiotomy or operative vaginal delivery or had recognized third- or fourth-degree lacerations. Twenty percent of women delivered without trauma, 34% with anterior (periurethral, periclitoral, or labial), 17% perineal, and 26%with both anterior and perineal trauma. Major trauma (trauma that involved perineal muscles or required suturing) occurred in 19%. At 3 months, few women (1%) had persistent perineal pain. AI (FIS score >0) was reported by 28% of women at 6 weeks and 24% at 3 months. Women with major trauma were more likely to report AI at 3 months (P=0.004), but presence or site of trauma was not related to AI complaints (all P=not significant [NS]). Complaints of UI were common at 28% at 6 weeks and 30% at 3 months. Fewer women reported IIQ-7 scores >0, at 17% and 12%, respectively. UI was not related to the presence or severity of trauma (all P=NS). Women with anterior trauma had fewer UI complaints than women with other sites of trauma (P=0.02). Dyspareunia was reported more often by women with major trauma than women with minor or no trauma (P=0.02). At 6 weeks, UI and AI were positively associated with directed forceful pushing in the second stage (P=0.003 and P=0.02, respectively). At 3 months, AI and UI were not associated with age, race/ethnicity, parity, body mass index, length of second stage, fetal weight, oxytocin or epidural use, or maternal position at delivery. CONCLUSIONS: This is the first prospective cohort study of low-risk healthy women that examines the impact of genital tract trauma on postpartum pelvic floor function. Complaints of pain were rare; AI and UI were reported more commonly. UI was inversely associated with anterior trauma, whereas AI was associated with perineal laceration. Directed forceful pushing in the second stage of labor may place women at risk in the short term for pelvic floor disorders.

War of the Words: Washington Tackles the Yugoslav Conflict

Preface Washington's Mindset Toward the Yugoslav Conflict Prelude to War: A History of Ethnic Tension (up to 1990) Yugoslav Ethnic Strife Emerges Amid Post-Cold War Changes (1990 to 1992) Ethnic Conflict Spreads to Bosnia-Hercegovina (October 1991 to mid-1992) War of Words, at Full Force (June to December 1992) Push Toward Intervention (December 1992 to February 1994) War of Force: U.S. Intervention in Bosnia (February 1994 to November 1995) War of Influence: Dayton and Beyond (November 1995 to 1998) Washington Fans the Flames of War in Kosovo (1998 to 1999) Appendices Notes Index

Comparison between two different concepts of lumbar posterior osteosynthesis implants A finite-element analysis

The present study is a numerical comparison using finite-element analysis (FEA) of two different concepts of spinal fixation devices when implanted. These implants are 1) the Easy®, “rigid” Screw/Rod (o 6mm) system; 2) the Twinflex®, “dynamic” system (o 2 X 2.5 mm ELF). A parameterised 3D FEA model of an L3-sacrum segment, developed by Lavaste, Skalli & Robin, was used. Geometric and mechanical models of each implant were then constructed, before being inserted in the spinal segment model. Then, for model validation, these two L3-S2 instrumented segmental models were submitted to similar boundary conditions as used in a previous in vitro comparison of the same implants. Flexion loaddisplacement curves were then controlled using experimental results. Loads acting on screws and longitudinal elements were calculated and analysed for a better understanding of the intrinsic differences between both constructs. Load-displacement responses of both constructs were quite similar (L3 sagittal rotation at 10 N.m = ~1.5°), while loads in the implant were not. For example, the axial push-in forces at the S1 screws were equal to 30 N for the Twinflex®, and 150 N for the Easy® Screw/Rod system. The pull-out forces at the S2 screws were respectively 100N and 200 N for the Twinflex and Screw/Rod Concept. At other levels, axial forces were all lower than 60 N, the Twinflex®, values being higher than the Easy® ones. Bending moments along screws were respectively 0.7 N.m and 1.4 N.m at the L3 level for the Twinflex® and the Easy® systems. At lower levels, values were all below 0.6 N.m, again with a reversed proportion. Bending moments calculated along longitudinal elements were always lower than 0.3 Nm for the Twinflex®, and up to 2 N.m for the Easy® system. Axial forces in the Twinflex® longitudinal elements were about 160 N, and about 100 N in the Easy® rods. Although the numerical approach mainly provides tendencies, it clearly seems that reducing flexural stiffness of lumbar fixation induces more homogeneous load transmission along the construct, and greatly reduces axial push-in/pull-out forces at the S1/S2 levels, and all this without reducing the rigidity of the whole construct. Conversely, it has been shown that “rigid” longitudinal elements may concentrate stresses at the construct extremities, relieving loads at intermediate levels at the same time, which may be the sign of a stress-shielding-like phenomenon. These differences arise from a fundamental difference between both kinds of longitudinal elements in the way they transmit loads. The o 6 mm rods mainly oppose a bending reaction torque to the applied flexion moment, whereas the Twinflex® construct mainly balances the applied flexion torque by an anterior compression of the anterior column, combined with posterior traction on its longitudinal elements (ELF).

Fluxon dynamics in long Josephson junctions in the presence of a temperature gradient or spatial nonuniformity

Fluxon dynamics in nonuniform Josephson junctions was studied both experimentally and theoretically. Two types of nonuniform junctions were considered: the first type had a nonuniform spatial distribution of critical and bias currents and the second had a temperature gradient applied along the junction. An analytical expression for the I-V curve in the presence of a temperature gradient or spatial nonuniformity was derived. It was shown that there is no static thermomagnetic Nernst effect due to Josephson fluxon motion despite the existence of a force pushing fluxons in the direction of smaller self-energy (from the cold to the hot end of the junction). A phenomenon, the {open_quotes}zero crossing flux flow step{close_quotes} (ZCFFS) with a nonzero voltage at a zero applied current, was observed in nonuniform long Josephson junctions. The phenomenon is due to the existence of a preferential direction for the Josephson vortex motion. ZCFFS{close_quote}s were observed at certain magnetic fields when the critical current in one direction but not the other becomes zero. Possible applications of nonuniform Josephson junctions in flux flow oscillators and as a superconducting diode are discussed. {copyright} {ital 1997} {ital The American Physical Society}

Analysis of Bond Stress Distributions in Pullout Specimens

Analytical expressions for predicting the bond stress versus slip response and the bond stress distribution for different types of pullout tests were developed. These analytical studies were mainly based on the use of bond stress versus slip responses obtained by experimental results. The responses of both pullout failures and splitting failures were predicted. For both types of failure modes the results from pullout tests, push-in tests, and a combination of pullout and push-in tests were investigated. The analyses showed that in a standard pullout test the ratio of maximum to average bond stress is about 1.37 for a pullout failure and about 1.26 for a splitting failure. A suitable combination of pullout and push-in forces can simulate a nearly uniform bond stress distribution with ratios of maximum to average bond stress of 1.10 and 1.11 for pullout and splitting failures, respectively.

A vortex ring impinging on a solid plane surface—Vortex structure and surface force

A joint numerical and experimental investigation has been performed to study a vortex ring normally impinging on a solid plane surface. Specific emphasis is placed upon the vortex structure and the associated surface force at Reynolds numbers between 500 and 2000. Along the line of Chang [Proc. R. Soc. London Ser. A 437, 517 (1992)], the force was viewed to be contributed by fluid elements with nonvanishing vorticity in the flow. This viewpoint enables the paper to provide a unique opportunity to shed light on the detailed mechanism which causes a small net surface force during the impingement process. It is found that the small net surface force results from the cancellation of a force pushing on the surface, due to the primary vortex ring, and a suction force, due to the induced boundary layer. Nevertheless, both the pushing and suction forces are much larger than that of the net surface force by several orders of magnitude. This fact provides proper directions for flow manipulation regarding forces exerted on the surface.

Abuse in Intimate Relationships

This study compared the reported incidence among males and females of dominance-possessiveness, sexual pressure, and use of physical force by one's partner for a sample of 130 married college students and 130 college students in dating relationships. Possessiveness was common and similar in incidence for married and dating students. Sexual pressure was reported by more married students, with dating students who were sexually involved to the extent of having intercourse more like marrieds. Use of moderate physical force—pushing, slapping, or hitting with an object—was experienced more often by the dating students. Males were as likely as females to report the partner engaging in these behaviors, and this applied to both the married and dating students. About 11% of both married and dating students reported consequences such as requiring medical attention or calling the police, which suggest more severe physical abuse. Note that this is a study of ever occurring incidences and not of battering per se. The theoretical implications for family violence literature of findings on courtship violence are discussed.

Conscious and subconscious arm movements: Application of signal detection theory to motor control

People sometimes carry out voluntary movements that do not seem to be consciously controlled. A familiar example is the board game Ouija. We hypothesize that movement speed is a primary determinant of whether a movement is conscious or subconscious. In support of this hypothesis, we show that mean movement velocity is slower when subjects imagine “a force pushing against the arm” than when they move the arm “as slowly as possible.” We also show that this outcome can be accounted for with signal detection theory, a theoretical tool that has so far been used primarily in the areas of perception and memory.

High electrostatic fields at ponderomotive laser driving of plasmas by nonlinear forces

The very short time step numerical two-fluid computation of laser-plasma interaction including complete nonlinear optical constants and the nonlinear (ponderomotive) force results in detailed information on plasma oscillations and damping and in the generation of electrostatic fields of 10 8 V/cm for neodymium glass laser pulses of 10 16 W/cm 2 intensity. The decoupling of interaction after caviton generation occurs as in preceding one-fluid calculations, after having permitted sufficient nonlinear force pushing of shells for fusion.