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PubMed2004

Foot and Ankle Research Retreat: concensus statement.

It is well recognized that the foot is a complex structure with 26 bones and over 30 articulations. Measuring its mechanics is a formidable task that is usually accomplished with a simplification of the system. The papers presented at this meeting provided some of the most current research in the area of multisegment foot modeling. The scientific discussions were rich as the small, intimate, and collegial environment encouraged an open flow of ideas. It was acknowledged that much work is still needed in the development of foot models to improve the measurement of foot mechanics. However, there was a strong sentiment among the participants to begin to apply these models to clinical problems. It was suggested that this be the focus of the next Foot and Ankle Research Retreat.

Ankle Joint↗

PubMed1994

[Antigliadin, antireticulin, antiendomysium antibodies: value in the diagnosis and follow-up of celiac disease in children].

In recent years, the clinical spectrum of coeliac disease has changed and forms with mild aspecific symptoms are today frequent. Therefore many infants are submitted to jejunal biopsy in order to exclude coeliac disease or to allow an early diagnosis. This has led to a search for a simple and reliable diagnostic test of coeliac disease in order to limit the use of jejunal biopsy. Recent data suggest that the study of serum antigliadin, antireticulin and antiendomysium antibodies may possibly play the role. In this paper the working group on coeliac disease of the Groupe Francophone de Gastroentérologie et Nutrition Pédiatriques expresses its view on the place of the dosages of these antibodies in the diagnosis and follow up procedures of coeliac disease in infants and children. At the present time, although it allows a simplification of the procedures, these dosages are presently not sufficiently reliable to serve as a substitute of jejunal biopsy.

Autoantibodies↗

PubMed1993

Aggregation and disaggregation kinetics of human blood platelets: Part I. Development and validation of a population balance method.

Hydrodynamic shear stress of sufficient intensity is known to cause platelet activation and aggregation and to alter the effects of biochemical platelet agonists and antagonists. In this work, a population balance equation (PBE) model is developed for analysis of platelet aggregation and disaggregation kinetics under the influence of a shear field. The model incorporates both aggregation and disaggregation by splitting and/or erosion mechanisms. This paper, the first of a series of three, deals with the formulation, simplification, and validation of the PBE and with the estimation of parameters involved in the PBE. These population parameters include collision efficiency, void fraction (related to the particle collision diameter), and the breakage rate coefficient. The platelet particle size distribution is determined experimentally, both initially and at some later times. The PBE can then be used to match satisfactorily the observed particle histograms, by appropriate choice of parameters of the model as functions of time, platelet size, and magnitude of physical or chemical stimuli. Besides providing information on adhesive forces and on the rates of aggregation and disaggregation, these parameters infer the physical properties of platelets and platelet aggregates. These properties are of potential value in increasing our understanding of the processes involved in thrombotic disease and/or therapy. A numerical procedure for solving the PBE is validated by application to simple cases for which analytical solutions are available. The model is applied to analysis of experiments, and parameter sensitivity studies are used to order the importance of the parameters and to reduce the complexity of the model. The simplified model is shown to give good agreement with experimental observations.

Adenosine Diphosphate↗

PubMedDate not supplied

Quality assurance versus QP(4)--the missing link.

First, quality is not easy. Second, basic process understanding, simplification and continuous improvement are equally difficult. We are vertically organized, yet our basic processes are horizontal with cross-functional boundaries. This recognition is the key to continued quality progress. Third, quality cascading is a key concept for progress. It is the most important factor in convincing the work force that we are serious about quality. Last, the concept of ownership is the most powerful force at work in our quality programs. Quality is not a destination, but a never-ending journey. We need to do things better today than yesterday. We need to be constantly on the lookout for ways to correct problems, prevent problems, and make improvements. Even when the customers' needs have been completely and precisely met, a better, more efficient approach may be possible. We need to take a broader view of the role that quality can play in achieving organizational and individual goals. We need to recognize that quality needn't cost more, yet it will improve customer satisfaction. Furthermore, quality involves more dimensions than just product or service; it applies to internal as well as external customers. We must recognize that everything the organization does has a quality component, and that everyone has a responsibility for quality. Accepting a new definition--and a new priority--for quality is essential, but not enough. For quality to become "the way we do business" in our organizations requires a break-through in action. We have to break out of established ways of thinking and acting. We have to learn new behaviors, and we need the skills to mandate and practice them.(ABSTRACT TRUNCATED AT 250 WORDS)

Consumer Behavior↗

PubMed1979

[Treatment of obstruction of the lacrimal ducts (author's transl)].

The present attitude towards the treatment of obstruction of the lacrimal ducts should be based on traditional methods, but modified to take into account recent advances which allow "modern surgery" to be applied. These new procedures are based on two relatively recent new acquisitions: 1) A precise knowledge of the physiology of the lacrimal pump, mainly due to the work of Lester T. Jones. It is important to know hen this pump has been destroyed as any attempt at repair is doomed to fail. We do not yet know how to reconstruct this pump. If minor damage has occurred however, attempts at repair operations may be successful. 2) Simplification of the operative procedure, both for dacryocystorhinostomies and lacodacryocystorhinostomies. Complex reconstructive procedures which often failed have been replaced by the application of a tube made of an inert material, and this is much simpler and gives much more constant results.

Constriction, Pathologic↗

PubMed1981

[Features of memorization disorders in different variants of endogenous depression].

Under study there were psychological processes underlying the deterioration of the memorizing effectiveness in patients with manic-depressive psychosis and schizophrenia. The author examined 96 patients with melancholic, anxious and apathic depressions. For examining the qualitative peculiarities of the mnestic activity use was made of methods of memorizing 10 works and of pictograms. The results of the experiment were analyzed on the basis of the mnestic activity theory suggested by A. R. Luria. As a result, it has been shown that the deterioration of the memorizing effectiveness in the patients with the melancholic depressions was due to a simplification and impoverishment of the mnestic processes; in patients with the anxious depressions it was due to disturbances of the coordination of those processes, and in patients with the apathic depressions to a distortion of the mnestic process quality.

Anxiety↗

PubMed1964

VOLUME CONDUCTOR FIELDS OF ACTION CURRENTS.

The formulation of Lorente de Nó for the potential distribution in a volume conductor due to a contained bioelectric source is reviewed. The aforementioned formula is based on data taken from the bioelectric source in air (excised). This work is extended to the derivation of a formula which depends upon quantities available from in situ measurements. The latter formula appears to simplify to the form[FORMULA: see text]where J(n) is the normal current density flow across the surface S(o) that bounds the bioelectric source. The simplification is considered in some detail for a hypothetical action potential on a circular cylindrical axon, and is shown to be adequately substantiated for this case.

Action Potentials↗

PubMed2001

Relationship between bond valence and bond softness of alkali halides and chalcogenides.

Established bond-valence parameter tables rely on the assumption that the bond-valence sum of a central atom is fully determined by interactions to atoms in its first coordination shell. In this work the influence of higher coordination shells is tested in detail for bonds between lithium and oxygen. It is demonstrated that the sum of the weak interactions with atoms of the second coordination shells significantly contributes to the valence sum and should therefore not be neglected. Since the independent refinement of the two parameters R(0) and b is hardly possible from the limited range of bond lengths occurring in the first coordination shell, the restriction of bond-valence sums to contributions from nearest neighbours implicated another far-reaching simplification: the postulation of a universally fixed value of the bond-valence parameter b which characterizes the shape of the bond-valence pseudopotential for the respective atom pair. However, recent more sophisticated applications of the bond-valence concept, e.g. to model ion-transport pathways in solid electrolytes, demand sensible estimates of the bond-valence sums for mobile ions not only at their equilibrium sites but also at interstitial sites and bottle-necks of transport pathways. Calculations of bond valences at these non-equilibrium sites require the knowledge of the actual shape of the bond-valence pseudopotential. A systematic route to a more realistic estimate of b for alkali halides and chalcogenides is developed in this work from an empirical correlation between b and the absolute softnesses of the interacting particles.

Journal Article↗

PubMed2004

Regulation of dendritic maintenance and growth by a mammalian 7-pass transmembrane cadherin.

Drosophila Flamingo is a 7-pass transmembrane cadherin that is necessary for dendritic patterning and axon guidance. How it works at the molecular level and whether homologs of Flamingo play similar roles in mammalian neurons or not have been unanswered questions. Here, we performed loss-of-function analysis using an RNAi system and organotypic brain slice cultures to address the role of a mammalian Flamingo homolog, Celsr2. Knocking down Celsr2 resulted in prominent simplification of dendritic arbors of cortical pyramidal neurons and Purkinje neurons, and this phenotype seemed to be due to branch retraction. Cadherin domain-mediated homophilic interaction appears to be required for the maintenance of dendritic branches. Furthermore, expression of various Celsr2 forms elicited distinct responses that were dependent on an extracellular subregion outside the cadherin domains and on a portion within the carboxyl intracellular tail. Based on these findings, we discuss how Celsr2 may regulate dendritic maintenance and growth.

Animals↗

PubMedDate not supplied

Equivalence relationships between stage-structured population models.

Matrix population models are widely applied in conservation ecology to help predict future population trends and guide conservation effort. Researchers must decide upon an appropriate level of model complexity, yet there is little theoretical work to guide such decisions. In this paper we present an analysis of a stage-structured model, and prove that the model's structure can be simplified and parameterised in such a way that the long-term growth rate, the stable-stage distribution and the generation time are all invariant to the simplification. We further show that for certain structures of model the simplified models require less effort in data collection. We also discuss features of the models which are not invariant to the simplification and the implications of our results for the selection of an appropriate model. We illustrate the ideas using a population model for short-tailed shearwaters (Puffinus tenuirostris). In this example, model simplification can increase parameter elasticity, indicating that an intermediate level of complexity is likely to be preferred.

Animals↗

PubMed2004

Control of eye orientation: where does the brain's role end and the muscle's begin?

Our understanding of how the brain controls eye movements has benefited enormously from the comparison of neuronal activity with eye movements and the quantification of these relationships with mathematical models. Although these early studies focused on horizontal and vertical eye movements, recent behavioural and modelling studies have illustrated the importance, but also the complexity, of extending previous conclusions to the problems of controlling eye and head orientation in three dimensions (3-D). An important facet in understanding 3-D eye orientation and movement has been the discovery of mobile, soft-tissue sheaths or 'pulleys' in the orbit which might influence the pulling direction of extraocular muscles. Appropriately placed pulleys could generate the eye-position-dependent tilt of the ocular rotation axes which are characteristic for eye movements which follow Listing's law. Based on such pulley models of the oculomotor plant it has recently been proposed that a simple two-dimensional (2-D) neural controller would be sufficient to generate correct 3-D eye orientation and movement. In contrast to this apparent simplification in oculomotor control, multiple behavioural observations suggest that the visuo-motor transformations, as well as the premotor circuitry for saccades, pursuit eye movements and the vestibulo-ocular reflexes, must include a neural controller which operates in 3-D, even when considering an eye plant with pulleys. This review summarizes the most recent work and ideas on this controversy. In addition, by proposing directly testable hypotheses, we point out that, in analogy to the previously successful steps towards elucidating the neural control of horizontal eye movements, we need a quantitative characterization first of motoneuron and next of premotor neuron properties in 3-D before we can succeed in gaining further insight into the neural control of 3-D motor behaviours.

Animals↗

PubMed1998

Periodontal therapeutics--a viable option?

Research in recent years in periodontology has seen a shift from surgery towards medicine. While surgery, particularly regenerative, and including implants, continues to form an important element of periodontal treatment, the volume of treatment required and the results of recent and ongoing non-surgical studies clearly show that most future periodontics will be based on a physician-type approach. Improved diagnostics based on more precise periodontal disease classification, simplification of mechanical oral hygiene equipment and procedures, and the development of conventional and non-conventional chemical and physical adjuncts may be expected to reduce the rate of common periodontal disease advance, resulting in less complex treatments, and more of the latter coming to lie within the competence of the generalist and the hygienist working together. The rationale for non-surgical adjunctive therapy is extensive, far beyond the usual antimicrobial logic. It will also be important to control the oral microflora for systemic reasons, since increasingly strong links are being established between focal infection of oral origin, much of it periodontal, and a range of systemic diseases, including coronary heart disease, stroke, gastrointestinal disorders, and low birth weight, apart from severe, overt systemic infections. All these developments derive from a greatly improved understanding of the fundamentally ecological nature of the natural microbial biofilm that is dental plaque, and of its interactions with its human host.

Anti-Bacterial Agents↗

PubMed1984

Recent progress in the diagnosis of brucellosis.

Progress since 1975 in the development of methods for the diagnosis of brucellosis is summarized. Standard serological diagnosis improved with increased use of acidified antigen agglutination and complement fixation tests. Immunoassays, tests based on the lysis of lipopolysaccharide coated erythrocytes and tests using new antigens have increased the sensitivity and specificity of serological results. The field of cellular immunology has seen the development and field evaluation of a skin test using refined antigens and the assessment of in vitro assays of cellular activity using purified protein and crude brucella antigens. Potential diagnostic uses of these methods are discussed. Bacteriological procedures were improved by introduction of stomachers and improved culture media. The isolation of new Brucella phages and development of a thin layer chromatography method for the determination of oxidation metabolic profiles were advanced in the characterization of Brucellae. Progress was also made in the development of immunoassays for the detection of Brucella antigens in host tissues. The selection of control groups, quality control studies and problems of standardization are areas that require greater attention in future methods development work. Major achievements of the period were 1) demonstrations that diagnosis sensitivity can be increased by new assays for antibody and cellular responses, 2) new methods to discriminate between anti-Brucella abortus and anti-Yersinia enterocolitica 0:9 responses, 3) a radial immunodiffusion test that detects most actively infected cattle, and 4) the simplification and extension of oxidative metabolic and phage typing tests. Advances in clinical microbiology and molecular biology have created new opportunities to improve diagnostic methods in the next decade.

Animals↗

PubMed1978

Synthesis of L-cysteine derivatives of immunotropic activity.

Working on the problem entitled "Synthesis of cysteine derivatives of immunotropic activity" the following compounds were synthesized; cysteine hydrazide and its hydrochloride, S-methylcysteine hydrazide hydrochloride, S, N, N-trimethylcysteine and S-benzylcysteinyl-S-benzylcysteine. We modified the synthesis of cysteine hydrazide and prepared its hydrochloride. This way a better yield and simplification of the synthesis were achieved. The above compounds were obtained with good yields.

Anti-Inflammatory Agents↗

PubMed2006

Transient signal analysis using complementary metal oxide semiconductor capacitive chemical microsensors.

This work explores the possibility to discriminate analytes based on their nonequilibrium signals in polymer-coated capacitive chemical microsensors. The analyte uptake in the chemically sensitive polymer layers of 3-7-microm thickness has been analyzed using a diffusion model and the dynamic sensor response data. The shapes of the response profiles have been calculated analytically. Despite the simplifications in the model, the observed transient signal profiles could be described accurately. Comparison of the measured diffusion coefficients (on the order of 10(-12) m2/s) with literature values measured at similar concentration levels showed good agreement. Concentration-independent diffusion coefficients for several analyte/polymer combinations (poly(etherurethane)/all analytes; poly(epichlorohydrin)/alcohols) as well as slightly concentration-dependent diffusion coefficients (poly(epichlorohydrin)/toluene or ethyl cellulose/toluene) have been found in the investigated concentration range of tens to hundreds of pascals gas-phase partial pressure. The diffusion times of water and the first aliphatic monohydric alcohols in the polymers are strongly correlated to their molecular size. The discrimination of these substances based on dynamic sensor data of a single sensor could be demonstrated. In particular, the analysis of mixtures of analytes with similar chemical behavior (water/ethanol or methanol/ethanol) by means of analyzing the response profile of single-exposure steps or by applying a series of decreasingly long alternating target gas exposure and carrier gas exposure steps has been performed.

Journal Article↗

PubMed1996

Simplification of the Elmslie-Trillat procedure for patellofemoral malalignment. Is medial capsulorraphy necessary?

We describe a modification of the Elmslie-Trillat operation which includes a lateral retinacular release and medial realignment of the tibial tuberosity, but omits medial capsulorraphy. Seventy-five patients were reviewed with a follow up longer than 2 years and the results compared with the conventional Elmslie-Trillat procedure, which consists of lateral release, medial realignment of the tuberosity and medial capsulorraphy. The simpler operation can work as well and the period of rehabilitation is shorter. The incidence of injury to the saphenous nerve is reduced and the cosmetic appearance is more satisfactory. We conclude that medial capsulorraphy is usually unnecessary in this type of procedure.

Female↗

PubMed2005

Generation of longitudinal vibrations in piano strings: from physics to sound synthesis.

Longitudinal vibration of piano strings greatly contributes to the distinctive character of low piano notes. In this paper a simplified modal model is developed, which describes the generation of phantom partials and longitudinal free modes jointly. The model is based on the simplification that the coupling from the transverse vibration to the longitudinal polarization is unidirectional. The modal formulation makes it possible to predict the prominent components of longitudinal vibration as a function of transverse modal frequencies. This provides a qualitative insight into the generation of longitudinal vibration, while the model is still capable of explaining the empirical results of earlier works. The semi-quantitative agreement with measurement results implies that the main source of phantom partials is the transverse to longitudinal coupling, while the string termination and the longitudinal to transverse coupling have only small influence. The results suggest that the longitudinal component of the tone can be treated as a quasi-harmonic spectrum with formantlike peaks at the longitudinal modal frequencies. The model is further simplified and applied for the real-time synthesis of piano sound with convincing sonic results.

Journal Article↗

PubMed2003

Modelling human burn injuries in a three-dimensional virtual environment.

This paper gives a work-in-progress report on our research project BurnCase, a virtual environment for modelling human burn injuries. The goal of the project is to simplify and improve the diagnosis and medical treatment of burns. Due to the lack of electronic and computational support for current diagnosis methods, enormous variations regarding the approximated size of burned skin regions exist. And although Simplifications like the Rule-Of-Nines-Method ([Weidringer, 2002]), Lund and Browder ([LundBrowder, 1944]) and others try to compensate for these errors, the fact remains that different physicians overestimate the BSA (Body Surface Area) by 20% up to 50%, depending on the different experience and subjectivity of the approximation process. Nevertheless, different supporting mechanisms have been developed to assist the process of burn region transfer so that after transferring all burned regions on the virtual human body, calculations can be applied in order to evaluate standard indices like the ABSI (Abbreviated Burn Severity Index), and Baux ([Baux, 1989]) as well as ICD10 (International Classification of Diseases) diagnosis encoding. The virtual body simulation is based on state-of-the-art 3D computer graphics (OpenGL). Thus a simulation system, providing a graphical user interface, allows surgeons to transfer a patient's burn injury regions onto an appropriate 3-dimensional model. As such, the BurnCase system improves surface determination by calculating region surfaces up to a precision of one cm2. This improves the average variation to less than 5%, limited by the precision of the surface transfer onto the virtual model. The system already allows the transfer of burned regions by using standard input devices. For this purpose different reference models of human bodies have been created in order to receive appropriate results based on measured physical data of different patients. Moreover, an underlying database stores all entered case studies so that it is possible to perform comparisons of burn cases and animation sequences of the healing process of single wounds or whole bodies. When used as centralized burn accident registration service, a huge knowledge base of burn diagnoses and consequent medical treatment will emerge. This knowledge base will allow medical advices and diagnosis support for any kind of burn accidents, and it will consequently improve and support the primary diagnosis process of burn accidents. Thus, an enormous reduction of time and costs of medical burn treatment will be reached.

Burns↗