Design methodology of prismatic form tool for lathe

The paper presents one of the possible ways for efficient design of prismatic form tool for lathe. The aim of research was to study theoretically and experimentally the design methodology of prismatic form tool for lathe. The starting point in defining the methodology was interrelation between the tool for lathe and the work piece during a turning operation, method of conjugate surfaces and basics of analytical geometry. Mathematical model was established for a chosen work piece profile and based on it a program was written, whereby technical documentation was generated for prismatic form tool. Technical documentation served to design the technology and thus mathematical model, i.e. design methodology was verified. The results have provided conditions for further research and development of prismatic form tools for lathe

Specifics of granite-based stone micro-cutting mechanism

В даній роботі показані результати дослідження, що були проведені на Машинобудівному факультеті в м. Белграді в області мікрорізання крихких матеріалів. Проаналізована взаємодія між алмазним зерном і мармуром та гранітом, що обробляються. Експериментально установлена зміна нормальної складової сили різання у функції швидкості різання і глибини проникнення при мікрорізанні на двох видах мармуру та граніту з родовищ в Республіці Сербії. На основі залишків на граніті і тріщин, що виникли, установлена критична глибина проникнення зерна, при якій виникає крихке руйнування. Наведені дослідження мають допомогти оптимізації процесу шліфування і полірування, які є домінуючими технологіями завершальної обробки граніту.The paper shows the results of investigations performed in the brittle materials micro-cutting at the Faculty of Mechanical Engineering, Belgrade University. The interactions between a single diamond grain and the machined marble and granite are analyzed. The change in the normal cutting force as a function of cutting speed and grain penetration depth was experimentally established in micro-cutting of two types of stone, marble and granite, originating from Serbia. Based on the grain traces on granite and the generated cracks, the critical grain penetration depth for the formation of brittle fracturing was established. The investigations mentioned should assist in the optimization of the grinding and polishing processes as technologies dominant in the granite finishing.В данной работе показаны результаты исследования, проводящиеся на Машиностроительном факультете в г. Белграде в области микрорезания хрупких материалов. Здесь проанализировано взаимодействие между алмазным зерном и обрабатывающимся мрамором и гранитом. Экспериментально установлено изменение нормальной составляющей силы резания в функции скорости резания и глубины проникновения при микрорезании на двух видах мрамора и гранита из местонахождений в Республике Сербии. На основании следов на граните и возникших трещин установлена критическая глубина проникновения зерна, при которой возникает хрупкое разрушение. Указанные исследования должны помогать оптимизации процесса шлифования и полировки, являющихся доминирующими технологиями окончательной обработки гранита

Impact evaluation of a community-based intervention for prevention of cardiovascular diseases in the slums of Nairobi: the SCALE-UP study.

BACKGROUND: A combination of increasing urbanization, behaviour change, and lack of health services in slums put the urban poor specifically at risk of cardiovascular disease (CVD). This study aimed to evaluate the impact of a community-based CVD prevention intervention on blood pressure (BP) and other CVD risk factors in a slum setting in Nairobi, Kenya. DESIGN: Prospective intervention study includes awareness campaigns, household visits for screening, and referral and treatment of people with hypertension. The primary outcome was overall change in mean systolic blood pressure (SBP), while secondary outcomes were changes in awareness of hypertension and other CVD risk factors. We evaluated the intervention's impact through consecutive cross-sectional surveys at baseline and after 18 months, comparing outcomes of intervention and control group, through a difference-in-difference method. RESULTS: We screened 1,531 and 1,233 participants in the intervention and control sites. We observed a significant reduction in mean SBP when comparing before and after measurements in both intervention and control groups, -2.75 mmHg (95% CI -4.33 to -1.18, p=0.001) and -1.67 mmHg (95% CI -3.17 to -0.17, p=0.029), respectively. Among people with hypertension at baseline, SBP was reduced by -14.82 mmHg (95% CI -18.04 to -11.61, p<0.001) in the intervention and -14.05 (95% CI -17.71 to -10.38, p<0.001) at the control site. However, comparing these two groups, we found no difference in changes in mean SBP or hypertension prevalence. CONCLUSIONS: We found significant declines in SBP over time in both intervention and control groups. However, we found no additional effect of a community-based intervention involving awareness campaigns, screening, referral, and treatment. Possible explanations include the beneficial effect of baseline measurements in the control group on behaviour and related BP levels, and the limited success of treatment and suboptimal adherence in the intervention group

Mechanisms involved in motor responses of the rat small intestine in healthy conditions and after Trichinella spiralis infection

Consultable des del TDXTítol obtingut de la portada digitalitzadaEl objetivo de este estudio es evaluar los mecanismos neurales y musculares implicados en la contracción y la relajación del músculo longitudinal del intestino delgado de rata en condiciones control y tras la infestación con Trichinella spiralis. Los segmentos del yeyuno y el íleon de ratas sanas e infestadas se montaron en un baño de órganos. Bajo estas condiciones se ha estudiado la contractilidad intestinal frente a la adición de agonistas y la respuesta motora a los neurotransmisores liberados por estimulación eléctrica de campo. 1. Grupo control. Los mecanismos implicados en la respuesta a dos principales donadores de óxido nítrico (NO), nitroprusiato sódico - SNP y morpholinosydnonimine hydrochloride - SIN-1, han sido caracterizados y comparados con las respuestas del neurotransmisor nitrérgico endógeno sobre el músculo longitudinal del íleon de rata. Además, intentamos determinar si la incubación prolongada y en exceso de NO puede, por sí misma, producir cambios en las respuestas contráctiles a sustancias que actúan esencialmente al nivel muscular. La implicación del calcio intra y extracelular bajo estas condiciones también ha sido evaluada. La respuesta que induce el neurotransmisor nitrérgico endógeno muestra grandes similitudes con la que provoca SNP pero difiere marcadamente de la respuesta provocada por SIN-1. El NO exógeno no modifica los mecanismos involucrados en las respuestas contráctiles inducidas por acetilcolina, sustancia P y KCl, incluyendo las funciones del calcio implicadas en estas respuestas. 2. Ratas infectadas con Trichinella spiralis. Estudiamos las alteraciones funcionales y morfológicas tanto en los segmentos inflamados del intestino delgado como en los no inflamados y libres de larvas de las ratas infestadas con Trichinella spiralis a diferentes tiempos posinfección. Cuando la infestación de la rata se lleve a cabo por administración oral de las larvas de T. spiralis, el parásito coloniza la parte proximal del intestino delgado -duodeno y yeyuno, pero no alcanza el íleon. De esta manera pudimos estudiar tanto los segmentos inflamados (yeyuno) como los no-inflamados y libres de larvas (íleon) del intestino delgado. Nuestros resultados evidencian que los cambios provocados por la infestación con T. spiralis ocurren en ambas partes del intestino. Los cambios más destacados se observaron en las respuestas motoras (contracciones y relajaciones) de los segmentos no infestados del íleon. Además, algunos de los cambios morfológicos y funcionales persistieron después de la completa desaparición de las evidencias histopatológicas de inflamación (hasta el día 72 de pos-infección). The objective of this study is to analyze neural and muscular mechanisms involved in contraction and relaxation of the longitudinal muscle of the rat small intestine in healthy conditions and after Trichinella spiralis infection. Whole thickness preparations taken from jejunum and ileum of both healthy and Trichinella spiralis-infected rats were mounted in a muscle bath. In such conditions motor responses elicited by agonist addition or by electric field stimulation (EFS) induced release of endogenous neurotransmitters were studied. 1. Healthy animals. The mechanisms mediating the response to two main nitric oxide (NO) donors, sodium nitroprusside (SNP) and morpholinosydnonimine hydrochloride (SIN-1), have been characterized and compared with the responses to endogenous nitrergic transmitter in the longitudinal smooth muscle of the rat ileum. Moreover, we also tried to determine if prolonged incubation and an excess of NO might produce by itself changes in the contractile responses to substances that act essentially at muscular level. The calcium-handling properties of the ileal smooth muscle in these conditions were also evaluated. The response to the nitrergic transmitter released from the enteric nerves bears great similarities with that caused by SNP but not by SIN-1. Exogenously added NO does not modify the pathways involved in acetylcholine-, substance P- and KCl-induced contractions, including the calcium flows involved in these responses. 2. Trichinella spiralis infected rats. We studied the time course of functional and morphological changes in both inflamed worm-positive and non-inflamed worm-negative intestinal segments of Trichinella Spiralis infected rats at different times post infection. When T. spiralis larvae are given orally, the parasite colonises the rat proximal small intestine - the duodenum and the jejunum but does not reach the ileum. Thus, in our study indeed both inflamed (jejunum) and non-inflamed (ileum) intestinal segments. Our results have provided evidence that changes provoked by T. spirals infection occur in both worm-free non-inflamed and worm-positive inflamed tissue, with the most prominent changes in contractile and relaxation responses in the uninfected ileal segments. Moreover, some of the morphological and functional changes persisted long after the complete recovery of the histopathological evidence of inflammation (until day 72 post-infection).Cilj ove studije je bio da analizira neuralne i muskularne mehanizme koji u_estvuju u kontrakcijama i relaksacijama longitudinalnog mi_i_a tankog crijeva pacova u kontrolnom uvjetima i nakon infekcije sa larvama Trichinelle spiralis. Odgovori integralnih segmenata pacovskog jejunuma i ileuma od zdravih i infestiranih pacova su bili studirani u organskom kupatilu. Motorni odgovor mi_i_a tankog crijeva induciran razli_itim agonistima i/ili elektri_nom stimulacijom (EFS) pod ovim uslovima je bio tema ove studije. 1 Kontrolna grupa. U prvom djelu analizirali smo mehanizme koji u_estvuju u odgovoru koji provociraju dva glavna donora nitri_nog oksida (NO), Na-nitroprusid (SNP) i morpholinosydnonimin hydrochlorid (SIN-1), u kontaktu sa longitudinalnim mi_i_em pacovskog ileuma. Mahanizmi ovih odgovora su bili karakterizirani i potom komparirani sa endogenim odgovorima nitri_nog neurotransmitora (provocirani sa EFS) koriste_i isti preparat. Tako_er smo poku_ali da ustanovimo da li bi prolongirana inkubacija sa NO ili sam NO u suvi_ku mogli inducirati promjene u kontrakcijama provociranim sa supstancijama koje eksluzivno djeluju na nivou glatke muskulature. Pod tim okolnostima mobilnost kalcijuma u glatkomi_i_noj _eliji ileuma tako_er je bila tema ove studije. Odgovori od endogenog nitri_nog neurotransmitora, oslobo_enog iz enteri_nih nerava, pokazuju veliku sli_nost sa odgovorima provociranim sa SNP ali ne i sa SIN-1. Egzogeno dodati NO nisu modificirali mehanizme implicirane u kontrakcijama provociranim sa acetilholinom, substancijom P ili KCl, uklju_uju_i tu i kalcijumovu mobilnost induciranu ovim agonistima. 2. Pacovi zarazeni sa Trichinellom spiralis. U drugom djelu izu_avali smo funkcionalne i morfolo_ke promjene u inflamatornim i upalom ne zahva_enim segmentima tankog crijeva pacova tokom upalnog procesa i u post-upalnom periodu. Da bi smo inducirali upalu izabrali samo eksperimentalni model infestiranih pacovima sa Trichinellom spiralis. Kada se pacovima larve T. spiralis daju per oralno, paraziti nastanjuju proksimalni dio tankog cijeva pacova - duodenum i jejunum, ali ne dose_u ileum. Na ovaj na_in bili smo u mogu_nosti da studiramo upalom zahva_ene dijelove tankog crijeva, kao na primjer jejunum, kao i djelove bez upalnih procesa i bez prisustva parazita koriste_i intestinalne segmente ileuma. Na_i rezultati su dokazali da promjene inducirane sa T. spirals zahvataju i parazit-negativna podrucja bez indikacija upale kao i parazit-pozitivna podrucja sa izra_enom upalom, kao i to da najizra_enije promjene u kontraktilnim i relaksatornim odgovorima su uo_ene u neupaljenim segmentima ileuma. Neke od morfolo_kih i funkcionalnih promjena su bile prisutne dugo nakon nestanka histopatolo_kih znakova inflamacije i trajale su _ak do 72. dana nakon infestacije pacova

Biološke karakteristike izolata Botrytis cinerea Pers. različite osetljivosti na dikarboksimide

A study of biological characteristics of both field and laboratory isolates revealed that highly resistant isolates were morphologically different from their original wild types. The majority of them were less pathogenic and produced less sclerotia than the original ones. Significant negative correlation between osmotic sensitivity and the degree of resistance was recorded. The correlation between micelium growth rate and resistance to dicarboximides was also significant and negative. Growth medium, acidity and growth temperature had less effect on the micelium growth rate of the highly resistant isolates than on the sensitive ones.U radu su proučavane biološke karakteristike izolata B. cinerea različite osetljivosti na dikarboksimide. Utvrđeno je da se visokorezistentni izolati morfološki razlikuju od izolata normalne osetljivosti. Oni su uglavnom slabije patogeni i formiraju manji broj sklerocija od izolata normalne osetljivosti. Zabeležena je visoka negativna korelacija između osetljivosti na povećan osmotski pritisak i rezistentnosti na dikarboksimide, kao i brzine rasta izolata i rezistentnosti na dikarboksimide. Uticaj temperature, vrste i kiselosti hranljive podloge na porast micelije visoko rezistentnih izolata B. cinerea slabije je izražen u odnosu na porast osetljivih izolata

Strukturmodell des Terminationsmoduls der Surfactin Synthetase

Nichtribosomale Peptidsynthetasen (NRPS) zeigen, trotz der hohen Anzahl ihrer Bausteine und der somit großen Vielfalt ihrer Produkte, eine konstante strukturelle Verwandtschaft. Die NRPS‐Systeme sind modular aufgebaut, wobei definierte Domänen die einzelnen Reaktionen katalysieren. Neben den katalytischen Domänen ist die Rolle des dynamischen Peptidyl‐Carrier‐Proteins (PCP) für das Verständnis der NRPS‐Wirkungsweise entscheidend. Studien vergleichbarer Systeme zeigen, dass die das Carrier‐ Protein umgebenden Linkerregionen aus Prolin‐ und Alanin‐reichen Sequenzen bestehen, wodurch die Bildung von Sekundärstrukturen erschwert und die Dynamik dieser Domänen unterstützt wird. Erst die in dieser Arbeit durchgeführte Arretierung der dynamischen PCP‐Domäne durch rationale Mutagenese ermöglichte die Beobachtung des Kristallwachstums und somit die erste Strukturaufklärung eines vollständigen NRPS‐Moduls. Die Struktur des Terminationsmoduls der Surfactin Synhtetase (SrfACS1003A) zeigt die Interaktion der dynamischen PCP‐Domäne mit der katalytischen Kondensationsdomäne (C‐Domäne). Das SrfAC‐Strukturmodell beschreibt die erste Struktur einer DC L‐Domäne. Desweiteren konnte die Bildung einer engen Interaktion zwischen der Kondensations‐ und den zwei Subdomänen der Adenylierungsdomäne (Acore‐ und Asub‐Domäne), die als Workbench bezeichnet wird, festgestellt werden. Dabei nimmt die Asub‐Domäne eine bisher nicht beobachtete Konformation ein. Die C‐ und Acore‐Domäne repräsentieren 83% der Masse eines Elongationsmodules (C‐, A‐ und PCP‐Domäne), auf deren starrem Gerüst die dynamische Asub‐ und PCP‐Domäne interagieren. Anschließende Untersuchungen mittels der Kleinwinkel‐Streuung (SAXS) zeigten, dass diese enge Interaktion auch im solvatisierten Zustand bestehen bleibt. Somit konnte die wichtige Rolle der Workbench, auch als Modell‐System für das generelle Verständniss der NRPS‐Systeme, bestätigt werden. Die Strukturaufklärung des vollständigen NRPS‐Moduls ermöglicht die eindeutige Definition der flankierenden PCP‐Linkerbereiche. Ihre sequenzielle Analyse zeigt, dass diese Bereiche aus Prolin‐ und Alanin‐reichen Sequenzen bestehen und somit nicht zur Bildung von Sekundärstrukturen neigen. Dagegen teilt der α‐helikale Linkerbereich zwischen der C‐ und A‐Domäne nicht die Affinität zu Prolin‐ und Alaninreichen Sequenzen und ist zur Bildung von Sekundärstrukturen fähig. Zusätzlich konnte in dem SrfAC‐S1003A‐Strukturmodell die spezifische Interaktion zweier Synthetasen über ein Helix‐Hand‐Motiv gezeigt werden. Dabei interagiert die C‐terminale α‐Helix (COM‐Helix) der ersten Synthetase mit dem in die C‐Domäne integrierten Hand‐Motiv der nachfolgenden Synthetase. Dadurch ist die spezifische Erkennung der Synthetasen untereinander gewährleistet, wodurch die Synthesereihenfolge erhalten bleibt (assembly line). Durch die Kombination mit der Bidomänen‐Struktur aus TycC konnte desweiteren ein multimodulares NRPS‐Modell erstellt werden. Dieses Modell zeigt eine linksläufige Schraubachse, bei der jedes Modul entlang der Assembly‐Line um 120° gedreht ist. Weitere Untersuchungen mittels CyoEM an trimodularen NRPS‐Systemen sollen diese Modul‐Anordnung bestätigen. Neben der globalen Architektur der NRPS, zeigt das Akzeptor‐Modell auch die ersten strukturell aufgeklärten Linkerbereiche einer swinging domain. Die in dieser Arbeit erstmals aufgeklärte Struktur eines NRPS‐Moduls ermöglicht neue synthetische und chemoenzymatische Ansätze für rationales Design und protein engineering an den nichtribosomalen Peptidsynthetasen und so den Zugang zu neuen biologisch wirksamen Peptidverbindungen

Reflection-aware static regression test selection

Regression test selection (RTS) aims to speed up regression testing by rerunning only tests that are affected by code changes. RTS can be performed using dynamic or static analysis techniques. A recent study showed that static and dynamic RTS can perform similarly for some medium-sized Java projects. However, the results also showed that static RTS can be sometimes unsafe, missing to select some tests that dynamic RTS selects, and reflection was the only cause of unsafety among the evaluated projects. In this thesis, we investigate five techniques—three purely static techniques and two hybrid static-dynamic techniques—to make static RTS safe with respect to reflection. We implemented four of these reflection-aware techniques as extensions to one reflection-unaware (RU) static RTS technique in a tool called STARTS. We evaluated the fifth technique but did not yet fully implement it. To assess reflection-aware SRTS techniques, we measured benefits and costs of four implemented reflection-aware techniques by comparing their end-to-end times with the RU technique and with RetestAll—the latter runs all tests after every code change. We also compared safety and precision of all five static RTS techniques relative to Ekstazi, a state-of-the-art dynamic RTS technique. Our results on 805 revisions of 22 open-source Java projects show that all reflection-aware techniques we evaluated can make static RTS safe with respect to reflection, but their costs vary widely. The best purely static technique in our study is based on border analysis with minimal border methods which avoids analyzing JDK and saves, on average, 14.1% of the end-to-end time of RetestAll. Furthermore, the results show that a hybrid technique based on per-test analysis is very promising in terms of safety and precision. On the other hand, the worst techniques were based on string analysis; these techniques are imprecise and often lead to selecting to re-run all tests. Taken together, these results show the need for more research into purely static techniques for making static RTS reflection aware

Discrete-Time Models Resulting From Dynamic Continuous-Time Perturbations In Phase-Amplitude Modulation-Demodulation Schemes

We consider discrete-time (DT) systems S in which a DT input is first tranformed to a continuous-time (CT) format by phase-amplitude modulation, then modified by a non-linear CT dynamical transformation F, and finally converted back to DT output using an ideal de-modulation scheme. Assuming that F belongs to a special class of CT Volterra series models with fixed degree and memory depth, we provide a complete characterization of S as a series connection of a DT Volterra series model of fixed degree and memory depth, and an LTI system with special properties. The result suggests a new, non-obvious, analytically motivated structure of digital compensation of analog nonlinear distortions (for example, those caused by power amplifiers) in digital communication systems. Results from a MATLAB simulation are used to demonstrate effectiveness of the new compensation scheme, as compared to the standard Volterra series approach.Comment: Submitted to the 14th European Control Conference (ECC15