The motion of the freely falling chain tip

The dynamics of the tip of the falling chain is analyzed. Results of laboratory experiments are presented and compared with results of numerical simulations. Time dependences of the velocity and the acceleration of the chain tip for a number of different initial conformations of the chain are determined. A simple analytical model of the system is also considered.Comment: 29 pages, 13 figure

Specificity of DNA methylation in the hypertensive kidney

Background: Evidence suggests that DNA methylation (5mC) is important in the development of essential hypertension (EH). The 5mC percentage, a measurement for global methylation studies, in peripheral blood leukocytes (PBL) has been previously associated with hypertension. Methylation patterns are tissue-specific, contributing to differences in transcriptional regulation and cellular differentiation. So far, there have been no studies of 5mC in the kidney – an important effector organ in EH. Furthermore, there has been no investigation of the relationship between 5mC patterns in the hypertensive kidney and PBLs. Aims: (i) To determine if global 5mC in the kidney is correlated to hypertension diagnosis and blood pressure (BP) regulation. (ii) To determine whether PBLs provide a surrogate for cross-tissue patterns of 5mC in the kidney. Methods: We used 96 human kidney and 76 human PBL samples from the TRANSLATE study to investigate global 5mC percentage. TRANSLATE consists of carefully characterized collections of "apparently healthy" specimens of human kidneys. Global methylation was determined using the 5mC ELISA kit (Zymo Research) that measures the total amount of 5mC present in a sample. Results: We found no association of global 5mC percentage in kidney (P=0.18) and PBL (P=0.54) with hypertension diagnosis, nor between PBL 5mC percentage and BP. However, a negative correlation was found between kidney 5mC percentage and systolic BP (r= –0.246; P <0.05), and diastolic BP (r= –0.319; P <0.01). This association was still evident after adjustment for antihypertensive medication for systolic BP (r= –0.210; P <0.05) and diastolic BP (r= –0.273; P <0.01). Furthermore, we found a strong positive correlation between normotensive kidneys and leukocyte 5mC percentages (r=0.864; P<0.01). Similarly, a strong positive correlation was evident for hypertensive kidneys and leukocyte 5mC percentages (r=0.916; P <0.01). Conclusion: Our findings show that kidney 5mC, but not PBL 5m C, is correlated to BP regulation. No relationship was evident for global 5mC and hypertension diagnosis, regardless of the tissue type studied. Furthermore, PBL 5mC global methylation percentage was highly correlated to kidney 5mC percentage. These results highlight the importance of further studies on the involvement of kidney DNA methylation in hypertension, as well as further investigation of the relationship between methylation patterns in the kidney and blood

Powikłania leczenia operacyjnego złamań stawowych kości piętowej

Wstęp: Autorzy pracy prezentują zarejestrowane w materiale własnym powikłania leczenia operacyjnego złamań stawowych kości piętowej z wykorzystaniem różnego rodzaju materiałów zespalających. Materiały i metody: Analizowanymi technikami operacyjnymi były zespolenie Westhuesa oraz jego modyfikacja z dodatkową stabilizacją odłamów kostnych drutami Kirschnera, a także przezskórna stabilizacja sposobem Rąpały. Materiał badań obejmuje lata od 1990 do 2012 roku, a stanowi go 82 operowanych, w tym 68 mężczyzn (83%) i 14 kobiet (17%). Analizowane złamania kości piętowej klasyfi kowano w oparciu o podział Essex-Lopresti. Wyniki: Autorzy pracy zwracają uwagę, że najczęściej rejestrowanymi powikłaniami leczenia operacyjnego złamań stawowych kości piętowej w obserwacji wczesnej są powikłania zakrzepowo-zatorowe oraz miejscowy odczyn zapalny skóry w miejscu wprowadzenia do kości materiału zespalającego, a w obserwacji odległej zespół pozakrzepowy i zaburzenia algodystroficzne. Wnioski: Czynnikami sprzyjającymi występowaniu tych powikłań jest morfologia samego złamania, zespolenie odłamów kostnych nadmierną liczbą elementów materiału zespalającego oraz długotrwałe unieruchomienie kończyny operowanej.Introduction: The authors present complications following surgical treatment of intra-articular calcaneus fractures, in regards to the surgical technique employed, based on their own clinical material. Materials and methods: The techniques analyzed included the Westhues’ technique and its modifi cation with additional bone stabilization by Kirschner wires and the percutaneous stabilization by Rapala. The research material covered the years from 1990 to 2012 and consists of 82 operated patients - 68 men (83%) and 14 women (17%). Analyzed calcaneus fractures were divided using the Essex-Lopresti classifi cation. Results: The authors of the article indicate that the most frequently registered complications of surgical treatment of intra-articular calcaneus fractures in early observation were thromboembolic complications and local infl ammatory reactions of the skin at the point of incision and placing the stabilizing material. During the long-term follow-up, the post-thrombotic syndrome and algodystrophic disorders were the most common. Conclusions: Factors contributing to the occurrence of the complications registered were fracture morphology, fixation of bone fragments by an excessive number of stabilizing materials and prolonged immobilization of the operated limb

Czynnościowe wyniki odległe oraz uwarunkowania fizjoterapeutyczne leczenia operacyjnego złamań stawowych kości piętowej

Wstęp: Autorzy pracy prezentują obserwacje własne z zakresu operacyjnego leczenia złamań stawowych kości piętowej z zastosowaniem przezskórnych zespoleń małoinwazyjnych w skojarzeniu ze zunifikowanym autorskim programem fizjoterapii. Materiały i metody: Są nimi zespolenie Westhuesa oraz jego modyfikacja z dodatkową stabilizacją odłamów kostnych drutami Kirschnera, a także przezskórna stabilizacja sposobem Rąpały. Materiał badań obejmuje lata 1990- 2012, a stanowi go 82 operowanych, w tym 68 mężczyzn (83%) i 14 kobiet (17%). Analizowane złamania kości piętowej klasyfikowano stosując podział Essex-Lopresti, a do oceny wyników czynnościowych w obserwacji odległej posłużono się kryteriami Creighton-Nebraska. Wyniki: Wśród mężczyzn z rozpoznanym złamaniem typu "języka", u których zastosowano zespolenie odłamów kostnych sposobem Westhuesa, wyniki dobre odnotowano u 12 operowanych, czyli u 17,6%, oraz wyniki zadowalające u pozostałych 7, czyli u 10,3%. W grupie kobiet leczonych z powodu złamań stawowych kości piętowej typu „języka” sposobem Westhuesa odnotowano wyniki dobre u 2 operowanych, czyli u 14,3%, oraz wynik zły u jednej z nich, co stanowi 7,1%. Wnioski: Na podstawie analizy zebranego materiału autorzy pracy skłaniają się do stwierdzenia, że wymienione zespolenia odłamów kostnych są jedynie z pozoru małoinwazyjne, a powikłane zwłaszcza powikłaniami skojarzonymi u większości operowanych prowadzą w obserwacji odległej do niekorzystnych wyników czynnościowych.Introduction: The authors present their own observations of the surgical treatment of articular calcaneal fractures using a minimally invasive percutaneous fixation in combination with the unifi ed self-developed physiotherapy program. Material and methods: The analyzed techniques include the Westhues’ technique and its modifi cation with additional stabilization of the bone fragments with Kirschner wires, as well as transdermal stabilization by Rąpała. The research material comprises 82 patients with intraarticular fractures - 68 men (83%) and 14 women (17%) treated surgically between 1990 and 2012. The analyzed calcaneus fractures were divided by Essex-Lopresti scale and evaluation of functional outcome at follow-up was based on the Creighton-Nebraska criteria. Results: Men with the "tongue type" fracture treated using the Westhues’ technique had good functional outcomes in 12 cases (17.6%) and acceptable in 7 cases (10.3%). Women with the “tongue type” fracture treated using the Westhues’ technique had good functional outcomes in 2 cases (14.3%) and in one case, poor (7.1%). Conclusions: After analysis of the material, the authors claim that minimally invasive techniques are not really minimally invasive, taking the observed complications into consideration in most of the patients, which lead to the poor functional outcome at long term follow-ups

Changes in handgrip force and blood lactate as response to simulated climbing competition

The aim of the study was to estimate post-competition changes in handgrip strength and blood lactate in climbers and relationships of the studied variables with declared climbing ability of the tested athletes. Twenty one male climbers volunteered to take part in the experiment. Each subject took part in simulated lead climbing competition on the artificial wall – (difficulty 7a in French scale). The blood lactate concentration was measured pre-climbing and then 3 min and 30 min post-climbing. Grip force of both hands (dominant and non-dominant) was measured twice – pre-climbing and 1 min post-climbing (semi-final). Maximum heart rate during climbing reached 181.4±7.7 beats per minute. Lactate concentration amounted to 6.35±1.50 mmol/l and 2.28±0.66 mmol/l 3 min and 30 min post-climbing, respectively. Handgrip force related to body mass (averaged for both hands) decreased significantly from 7.39±1.30 N/kg pre-climbing to 6.57±1.05 N/kg 1 min post-climbing. Self reported climbing ability was correlated with lactate concentration and handgrip force, as well. It was demonstrated that athletes reporting higher climbing ability showed better lactate recovery

Vascular architecture of the human uterine cervix, as assessed in light and scanning electron microscopy

Objectives. The aim of this study was to visualize and describe the vasculature of the human uterine cervix.Materials and Methods. The material for this study was obtained from women (age between 20 to 45 years) during autopsy. The material was collected not later than 24 hours post-mortem. This study was performed using uteri from cadavers of menstruating nulliparas (33 uteri) and menstruating multiparas (27 uteri). Collected uteri were perfused via the afferent vessels with Mercox resin (for corrosion-casting and SEM assessment) or acrylic paint solution (light microscopy assessment). The research protocol was approved by the Jagiellonian University Ethics Committee (registry KBET/121/8/2007).Results. In all cases bilateral cervical branches (1-4), originating from the uterine artery, were found. Both in the vaginal and supravaginal parts of the cervix, four distinct vascular zones were found. In the pericanalar zone ran small veins, responsible for draining the mucosal capillaries. Both in the muscular layer, as well as in the pericanalar zone, arterioles and venules passed close to each other, often adjoining.Conclusions. This study does not confirm the existence of a single “cervicovaginal” artery, but shows that the vascular supply of the cervix comes from several vessels. It also introduces the idea of two systems, responsible for draining blood from the mucosal capillaries. Neither assessment in light microscopy nor in SEM has revealed any differences between multiparas and nulliparas, as to the vascular architecture of the cervix

A Pixel Vertex Tracker for the TESLA Detector

In order to fully exploit the physics potential of a e+e- linear collider, such as TESLA, a Vertex Tracker providing high resolution track reconstruction is required. Hybrid Silicon pixel sensors are an attractive sensor technology option due to their read-out speed and radiation hardness, favoured in the high rate TESLA environment, but have been so far limited by the achievable single point space resolution. A novel layout of pixel detectors with interleaved cells to improve their spatial resolution is introduced and the results of the characterisation of a first set of test structures are discussed. In this note, a conceptual design of the TESLA Vertex Tracker, based on hybrid pixel sensors is presentedComment: 20 pages, 11 figure

A Comparative Finite-Element Analysis of Bone Failure and Load Transfer of Osseointegrated Prostheses Fixations

An alternative solution to conventional stump–socket prosthetic limb attachment is offered by direct skeletal fixation. This study aimed to assess two percutaneous trans-femoral implants, the OPRA system (Integrum AB, Göteborg, Sweden), and the ISP Endo/Exo prosthesis (ESKA Implants AG, Lübeck, Germany) on bone failure and stem–bone interface mechanics both early post-operative (before bony ingrowth) and after full bone ingrowth. Moreover, mechanical consequences of implantation of those implants in terms of changed loading pattern within the bone and potential consequences on long-term bone remodeling were studied using finite-element models that represent the intact femur and implants fitted in amputated femora. Two experimentally measured loads from the normal walking cycle were applied. The analyses revealed that implantation of percutaneous prostheses had considerable effects on stress and strain energy density levels in bone. This was not only caused by the implant itself, but also by changed loading conditions in the amputated leg. The ISP design promoted slightly more physiological strain energy distribution (favoring long-term bone maintenance), but the OPRA design generated lower bone stresses (reducing bone fracture risk). The safety factor against mechanical failure of the two percutaneous designs was relatively low, which could be improved by design optimization of the implants