Biomass, leaf water potential (Ψl), net photosynthetic rate (PN), transpiration rate (E), stomatal conductance (gs), leaf to air temperature difference (Tdiff), and instantaneous water use efficiency (WUE) were measured in the seedlings of Dalbergia sissoo Roxb. grown under irrigation of 20 (W1), 14 (W2), 10 (W3), and 8 (W4) mm. Treatments were maintained by re-irrigation when water content of the soil reached 7.4% in W1, 5.6% in W2, 4.3% in W3, and 3.2% in W4. Seedlings in a control (W5) were left without irrigation after maintaining the soil field capacity (10.7%). Seedlings of W1 had highest biomass that was one tenth in W5. Biomass allocation was highest in leaf in W2 and in root in W4 and W5 treatments. Difference between predawn leaf water potential (ΨPd) and midday (Ψmid) increased with soil water stress and with vapour pressure deficit (VPD) in April and May slowing down the recovery in plant leaf water status after transpiration loss. PN, E, and gs declined and Tdiff increased from W1 to W5. Their values were highly significant in April and May for the severely stressed seedlings of W4 and W5. PN increased from 08:00 to 10:00 and E increased until 13:00 within the day for most of the seedlings whereas gs decreased throughout the day from 08:00 to 17:00. PN and E were highest in March but their values were low in January, February, April, and May. Large variations in physiological variables to air temperature, photosynthetically active radiation, and vapour pressure deficit (VPD) indicated greater sensitivity of the species to environmental factors. WUE increased from W1 to W2 but decreased drastically at high water stress particularly during hot summer showing a kind of adaptation in D. sissoo to water stress. However, low biomass and reduced physiological functions at <50% of soil field capacity suggest that this species does not produce significant biomass at severe soil water stress or drought of a prolonged period. and B. Singh, G. Singh.
The present article introduces a novel method of characterizing the macromechanical cartilage properties based on dynamic testing. The proposed approach of instrumented impact testing shows the possibility of more detailed investigation of the acting dynamic forces and corresponding deformations within the wide range of strain rates and loads, including the unloading part of stress-strain curves and hysteresis loops. The presented results of the unconfined compression testing of both the native joint cartilage tissues and potential substitute materials outlined the opportunity to measure the dissipation energy and thus to identify the initial mechanical deterioration symptoms and to introduce a better definition of material damage. Based on the analysis of measured specimen deformation, the intact and pathologically changed cartilage tissue can be distinguished and the differences revealed., F. Varga, M. Držík, M. Handl, J. Chlpík, P. Kos, E. Filová, M. Rampichová, A. Nečas, T. Trč, E. Amler., and Obsahuje bibliografii
Biomechanics has widely expanded in the last decades. The last development of computers provides new possibilities in this field. Problems can be solved faster and can be more extensive. One of these problems is the biomechanical model of human body. Its realisaton is practically impossible without using computers, because it is necessary to solve systems of thousands of equations.
There are several software packages that enable human body modeling. One of them is the PAM environment [15] developed by the ESI Group International. This computational system is based on the Finite Element Method and is one of the mostly used systems for crash test simulations.
Various human body models for various purposes are developed. Pregnant female model serve to optimize safety systems in cars to be more friendly to pregnant abdomen. and Obsahuje seznam literatury
The presented work is focused on the biomechanical study of the dental disk implant. The first part of the study deals with the strain analysis of the affected bone tissue and the dental implant loaded in the coronoapical direction by force 190 N. The study includes three types of implant anchorge, four degrees (stages) of osseointegration and nine degrees describing the quality of the cancellous bone. Two types of the disk implant were researched: single-disk and double-disk implant. Biomechanical study of the implant was focused on a stress-strain analysis of the affected bone rissue. The highest influence on the stresses in the bone tissue was primarily an implant anchorage. By the application of correlation relationships between Young modulus and the apparent density of the bone tissue - which is measurable in patients - we achieved the variable presented in this study. and Obsahuje seznam literatury
The presented work follows the first part [1], which is focused on the analysis of bone tissue in terms of dependence of bone tissue 'quality' and its subsequent behaviour based on the stress around the disk implant when biting.
This second part is focused on the stress-strain analysis (and tolerability) of disk implants as loaded during the masticating process.
The study includes two types of disk implants (single-disk and double-disk), three types of anchorage, four degrees (stages) of osseointegration in three quality degrees of the cancellous bone. The study, as expected, has shown that the problematic area of he implants is a transition between the implant body and the disk component, where the equivalent stress in the analyzed implants reaches 700 MPa. and Obsahuje seznam literatury
Orthopaedists in the Czech Republic use corrective braces of type Cheneau or Cerny for conservative treatment of non skeletal scoliosis. The brace has force effects on a child spine and if it is used for enough long time the spine defect is corrected. The brace is made individually for each patient in this way: first, the negative plaster form of a child trunk and then the positive plaster form are made. The positive plaster form is deepened in the places where brace has to push on the patient trunk. The laminate brace made according to this plaster form pushes the child trunk like a tight shoe principle. The paper shows the manner of determination and computer algorithms for solving of the stress state in vertebrae and inter-vertebrae discs and the spinal curve correction under brace force effects for a concrete child patient. The pathologic spinal curve deformities are measured on the X-ray of patient. The spine stress state and spine deformation correction are solved as a beam (spine) on an elastic ground (soft tissue). There are used two algorithms. The 1st algorithm solves the spine stress state and deformation under brace force effect given by displacements of trunk surface. The 2nd algorithm has as input the spinal curves of a patient with and without brace measured on the X-rays. The difference of the two curves is the spine deformity corretions and the spine stress state and necessary trunk surface displacement are the results. If the ideal spine curve is set as the curve under brace effect then the trunk surface is equal to the optimal brace form. The calculation algorithm and parameters ware verified with treatment courses. The trunk surface load was checked by sensor plates which ware put into braces to measure the load values between the brace and the child trunk surface. and Obsahuje seznam literatury
Článek vychází ze zkušeností autora, který se po dlouhé praxi ve výuce mechaniky a výzkumu v oboru fyziky polymerů nyní převážně zabývá biomechanikou. Impresionistickou metodou se snaží na několika příkladech ukázat, jak vidí úlohu mechaniky a především mechaniky kontinua a reologie v biomechanice. Zabývá se i otázkou vzájemných vztahů různých profesí v multidisciplinárním oboru. Úlohu mechaniky v biomechanice vidí především v co nejhlubším pochopení fyzikální podstaty biologických dějů a jejich co nejadekvátnějším vyjádřením v rámci fyziky, kterou je však často nutno užívat ve formě podstatně složitější, než je fyzika středoškolská., This article is based on the author's experiences as both a university lecturer of mechanics and a researcher in polymer physics working now in biomechanics. The impression of the role of mechanics in biomechanics is shown on several examples taken mainly from the author's experience. The interrelations of different processes engaged in the multidisciplinary biomechanics are also discussed. The role of mechanics in biomechanics is seen in deep physical understanding of the solved problem and in adequate physical interpretation of the gained results. As the biomechanical problems are often very difficult to solve, the more general physics that is that taught at grammar schools must be used. The physician's knowledge of the human body functions are so deep that only the main features of the knowledge may be expressed in physical terms even if very advanced theories are used., Antonín Havránek., and Obsahuje bibliografii
In model experíments with isolated water-soluble proteins of chloroplasts the interaction of acetylcholinesterase (AChE) with ribulose-l,5-bisphosphate carboxylase (RuBPC), plastocyanin (PC), cytochrome / (cyt f) and ferredoxin (Fd) was studied. The acetylthiocholine (AThCh) hydrolysis by AChE was stimulated by other proteins by 20-200 %. Maximal effect was observed after the addition of PC. AChE itself did not affect redox capability of the electron transport carriers. The RuBPC activity was inhibited by 70 % on the AChE increase in the reaction medium. The level of inhibition was higher in the presence of the AChE inhibitors physostigmine and neostigmine, as well as the catecholamine noradrenaline. Biomediators acetylcholine (ACh), noradrenaline, adrenaline and the anticholinesterase drugs neostigmine and physostigmine slightly (by 5-20 %) inhibited the C02-fixing enzyme activity. Mutual regulation of AChE and RuBPC may exist in chloroplasts.
Pro řadu biomedicínských aplikací je zásadní interakce mezi biologickým prostředím a povrchem pevné látky. Diamant jako materiál sdružuje v tomto ohledu výborné polovodičové, mechanické, chemické i biologické vlastnosti a lze ho připravovat synteticky i na velké plochy. Zde ukazujeme, jaký vliv má atomární zakončení povrchu diamantu na uspořádání proteinů a buněk a jak toto biologické rozhraní naopak ovlivňuje jeho elektronické vlastnosti. Dosažené poznatky jsou přínosné pro využití unikárních vlastností diamantu v medicíně a dalších oborech., Understanding interactions between the biological environment and solid state surfaces is crucial for a wide range of biomedical applications. In this context, diamond as a material merges excellent semiconducting, mechanical, chemical as well as biological properties and it can be prepared synthetically even at large areas. here we show how atomic termination of diamond surfaces inluences arrangement of proteins and cells and how such biological interface influences electronic properties of diamond. Attained knowledge is fundamental for employing diamond unique properties in medicine and other fields., Bohuslav Rezek, Egor Ukraintsev, Marie Krátká, Alexander Kromka, Antonín Brož, Marie Kalbáčová., and Obsahuje bibliografii
Discovering of new possibilities of treatment and diagnostics of people is one of the characteristics of medicine as a science. Biomedical research in various forms accompanies mankind since time immemorial. The effort to discover „the new“ led in the past, apart from positive results, also to misusing of people in nonsensical experiments. This experience resulted in adopting a number of legal regulations determining limits of biomedical research, good practice and most of all protection of rights for research participants. A research activity is not only connected with issues relating to conditions of its implementation, but also to issues relating to protection of its results. Apart from the patent protection of new drugs and medical aids, it is also necessary to consider protection of new diagnostic and therapeutic methods. As the result of the research does not have to be only a drug, or a medical aid, but also a patient treatment procedure. The Act no. 576/2004 Coll. on Medical Care binds the project researcher to make it possible for the expert public to access results (hence the new method) of his/her work. Past legislation in Slovakia and the Czech Republic used to recognize copyright for originators of new methods. This legislation was cancelled without its replacement. Based upon the research characteristics, the rights for originators of a new method could be subordinated under rights similar to industrial rights. The current legal order of Slovakia does not sufficiently protect the rights for originators of new methods, which result from biomedical research. and Objavovanie nových možností liečby a diagnostiky ľudí je jednou z charakteristík medicíny ako vedy. Biomedicínsky výskum v rôznych podobách sprevádza ľudstvo od nepamäti. Snaha objavovať „nové“ v minulosti viedla okrem pozitívnych výsledkom aj k zneužívaniu ľudí pri nezmyselných pokusoch. Táto skúsenosť vyústila do prijatia množstva právnych predpisov stanovujúcich mantinely biomedicínskeho výskum, správnu prax a predovšetkým ochranu práv účastníkov výskumu. S výskumnou činnosťou nie sú spojené iba otázky zabezpečenia podmienok jeho realizovania, ale aj otázky ochrany jeho výsledkov. Okrem patentovej ochrany nových liekov a zdravotníckych pomôcok prichádza do úvahy aj ochrana nových diagnostických a terapeutických metód. Výsledkom výskumu totiž nemusí byť iba liek, či zdravotnícka pomôcka, ale aj postup pri liečbe pacienta. Zákon č. 576/2004 Z.z. o zdravotnej starostlivosti zaväzuje riešiteľa výskumného projektu, aby výsledky svojej práce (ergo novú metódu) sprístupnil odbornej verejnosti. V minulosti bola na Slovensku a v Českej republike právna úprava ktorá priznávala práva z autorstva pre pôvodcov nových metód. Táto úprava bola zrušená bez jej náhrady. Práva pôvodcu novej metódy by sme na základe charakteristík výskumu mohli podradiť pod práva obdobné priemyselným právam. V súčasnosti právny poriadok Slovenska dostatočne nechráni práva pôvodcov nových metód, ktoré sú výsledkom biomedicínskeho výskumu.