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PubMed2000

Deprivation and poor health in rural areas: inequalities hidden by averages.

Poor health and social deprivation scores in 570 wards in East Anglia, UK, were much less associated in rural than in urban areas. The deprivation measure most closely related to poor health in the least accessible rural wards was male unemployment, but use of this measure did not remove the urban-rural gradient of association strength. Neither did replacing wards by smaller enumeration districts as the units of analysis. The differences between urban and rural correlations were removed by restricting the comparison to wards with the same unemployment range and combining pairs of rural wards with similar deprivation values. Apparent differences between rural and urban associations are therefore not due to the choice of deprivation indices or census areas but are artifacts of the greater internal variability, smaller average deprivation range and smaller population size of rural small areas. Deprived people with poor health in rural areas are hidden by favourable averages of health and deprivation measures and do not benefit from resource allocations based on area values.

Cultural Deprivation↗
PubMed2003

[Intrahospital mortality after discharge from the ICU (hidden mortality) in patients who required mechanical ventilation].

BACKGROUND AND OBJECTIVE: Our goal was to determine the hidden mortality (HM) in patients who underwent an episode of mechanical ventilation (MV). We also analyzed the factors associated with an increase in the risk of hidden mortality. PATIENTS AND METHOD: Prospective cohort study. Patients admitted to an ICU who required MV and who were monitored until their discharge from hospital. We performed a multivariate study with a logistic regression model including all the variables that were present in a univariate analysis p < 0.20. RESULTS: Forty-one of the 215 patients who were discharged from the ICU died when they were admitted to hospital, which represents a hidden mortality rate of 19% (CI 95% 11%-27%). A mean period of 9 days elapsed between discharge from the ICU and patient's death, with 25% of patients dying within the first two days. Commonest cause of death was respiratory failure (37%). Factors independently associated with an increase in the risk of hidden mortality were (values expressed as adjusted odds ratio (CI 95%): age > 74 years 1.15 (1.01 to 1.26) (p = 0.02); APACHE II > 29 1.14 (1.01 to 1.27) (p = 0.04); reason for MV being coma 1.21 (1.07 to 1.37) (p = 0.002); reason for MV being cardiopulmonary arrest 1.28 (1.18 to 1.68) (p < 0.001); tracheotomy in ICU 1.31 (1.19 to 1.68) (p < 0.001) and stay in the ICU longer than 16 days 1.35 (1.01 to1.70) (p = 0.04). CONCLUSIONS: An important number of patients discharged from the ICU after an episode of MV die in hospital. Risk factors associated with an increased risk of death in hospital identify a group of patients who, after excluding those with non-cardiopulmonary resuscitation orders, would possibly benefit from high surveillance or intermediate care units.

APACHE↗
PubMed2006

Hierarchical stochastic image grammars for classification and segmentation.

We develop a new class of hierarchical stochastic image models called spatial random trees (SRTs) which admit polynomial-complexity exact inference algorithms. Our framework of multitree dictionaries is the starting point for this construction. SRTs are stochastic hidden tree models whose leaves are associated with image data. The states at the tree nodes are random variables, and, in addition, the structure of the tree is random and is generated by a probabilistic grammar. We describe an efficient recursive algorithm for obtaining the maximum a posteriori estimate of both the tree structure and the tree states given an image. We also develop an efficient procedure for performing one iteration of the expectation-maximization algorithm and use it to estimate the model parameters from a set of training images. We address other inference problems arising in applications such as maximization of posterior marginals and hypothesis testing. Our models and algorithms are illustrated through several image classification and segmentation experiments, ranging from the segmentation of synthetic images to the classification of natural photographs and the segmentation of scanned documents. In each case, we show that our method substantially improves accuracy over a variety of existing methods.

Algorithms↗
PubMed2006

Thermoregulation: some concepts have changed. Functional architecture of the thermoregulatory system.

While summarizing the current understanding of how body temperature (T(b)) is regulated, this review discusses the recent progress in the following areas: central and peripheral thermosensitivity and temperature-activated transient receptor potential (TRP) channels; afferent neuronal pathways from peripheral thermosensors; and efferent thermoeffector pathways. It is proposed that activation of temperature-sensitive TRP channels is a mechanism of peripheral thermosensitivity. Special attention is paid to the functional architecture of the thermoregulatory system. The notion that deep T(b) is regulated by a unified system with a single controller is rejected. It is proposed that T(b) is regulated by independent thermoeffector loops, each having its own afferent and efferent branches. The activity of each thermoeffector is triggered by a unique combination of shell and core T(b)s. Temperature-dependent phase transitions in thermosensory neurons cause sequential activation of all neurons of the corresponding thermoeffector loop and eventually a thermoeffector response. No computation of an integrated T(b) or its comparison with an obvious or hidden set point of a unified system is necessary. Coordination between thermoeffectors is achieved through their common controlled variable, T(b). The described model incorporates Kobayashi's views, but Kobayashi's proposal to eliminate the term sensor is rejected. A case against the term set point is also made. Because this term is historically associated with a unified control system, it is more misleading than informative. The term balance point is proposed to designate the regulated level of T(b) and to attract attention to the multiple feedback, feedforward, and open-loop components that contribute to thermal balance.

Afferent Pathways↗
PubMed2004

Forecasting model for the incidence of hepatitis A based on artificial neural network.

AIM: To study the application of artificial neural network (ANN) in forecasting the incidence of hepatitis A, which had an autoregression phenomenon. METHODS: The data of the incidence of hepatitis A in Liaoning Province from 1981 to 2001 were obtained from Liaoning Disease Control and Prevention Center. We used the autoregressive integrated moving average (ARIMA) model of time series analysis to determine whether there was any autoregression phenomenon in the data. Then the data of the incidence were switched into [0,1] intervals as the network theoretical output. The data from 1981 to 1997 were used as the training and verifying sets and the data from 1998 to 2001 were made up into the test set. STATISTICA neural network (ST NN) was used to construct, train and simulate the artificial neural network. RESULTS: Twenty-four networks were tested and seven were retained. The best network we found had excellent performance, its regression ratio was 0.73, and its correlation was 0.69. There were 2 input variables in the network, one was AR(1), and the other was time. The number of units in hidden layer was 3. In ARIMA time series analysis results, the best model was first order autoregression without difference and smoothness. The total sum square error of the ANN model was 9 090.21, the sum square error of the training set and testing set was 8 377.52 and 712.69, respectively, they were all less than that of ARIMA model. The corresponding value of ARIMA was 12 291.79, 8 944.95 and 3 346.84, respectively. The correlation coefficient of nonlinear regression (R(NL)) of ANN was 0.71, while the R(NL) of ARIMA linear autoregression model was 0.66. CONCLUSION: ANN is superior to conventional methods in forecasting the incidence of hepatitis A which has an autoregression phenomenon.

China↗
PubMed2003

Artificial neural networks (ANNs) and modeling of powder flow.

Effects of micromeritic properties (bulk, tapped and particle density, particle size and shape) on the flow rate through circular orifices are investigated, for three pharmaceutical excipients (Lactose, Emcompress and Starch) separated in four sieve fractions, and are modeled with the help of artificial neural networks (ANNs). Eight variables were selected as inputs and correlated by applying the Spearman product-moment correlation matrix and the visual component planes of trained Self-Organizing Maps (SOMs). Back-propagation feed-forward ANN with six hidden units in a single hidden layer was selected for modeling experimental data and its predictions were compared with those of the flow equation proposed by. It was found that SOMs are efficient for the identification of co-linearity in the input variables and the ANN is superior to the flow equation since it does not require separate regression for each excipient and its predictive ability is higher. Besides the orifice diameter, most influential and important variable was the difference between tapped and bulk density. From the pruned ANN an approximate non-linear model was extracted, which describes powder flow rate in terms of the four network's input variables of the greatest predictive importance or saliency (difference between tapped and bulk density (x(2)), orifice diameter (x(3)), circle equivalent particle diameter (x(4)) and particle density [equation in text].

Excipients↗
PubMed2001

Parameter-adaptive identical synchronization disclosing Lorenz chaotic masking.

A parameter-adaptive rule that globally synchronizes oscillatory Lorenz chaotic systems with initially different parameter values is reported. In principle, the adaptive rule requires access to the three state variables of the drive system but it has been readapted to work with the exclusive knowledge of only one variable, a potential message carrier. The rule is very robust and can be used to trace parameter modulation conveying hidden messages. The driven system is defined according to a drive-driven type of coupling that guarantees synchronization if parameters are identical. From any arbitrary initial state, the parameters of the driven system are dynamically adapted to reach convergence to the drive parameter values. At this point, synchronization mismatch or parameter tracing is used to unmask any potential hidden message.

Journal Article↗
PubMed2006

Prediction of headache response in migraine treatment.

Triptans are efficacious for the acute treatment of migraine attacks. Yet, defining a concentration-effect relation for these compounds is difficult as the dynamics of the migraine attack are not thoroughly understood. The objective of this investigation was to develop a disease model to predict measures of headache in randomized placebo-controlled clinical trials investigating oral sumatriptan as a paradigm compound. A hidden Markov model based on the states of response (no relief, relief, and pain free) and headache scores (observed variable) was used in conjunction with population pharmacokinetics. Model parameters were capable of predicting the course of headache relief, pain-free status and headache recurrence. It was shown that sumatriptan shortens mean transit times between states by up to 5 h. The potency of sumatriptan (EC(50)) was 9 ng/ml. These findings demonstrate the value of combining pharmacokinetic and efficacy information to model disease and characterize time-independent drug properties in a population of migraineurs.

Comorbidity↗
PubMed2005

Use of artificial genomes in assessing methods for atypical gene detection.

Parametric methods for identifying laterally transferred genes exploit the directional mutational biases unique to each genome. Yet the development of new, more robust methods--as well as the evaluation and proper implementation of existing methods--relies on an arbitrary assessment of performance using real genomes, where the evolutionary histories of genes are not known. We have used the framework of a generalized hidden Markov model to create artificial genomes modeled after genuine genomes. To model a genome, "core" genes--those displaying patterns of mutational biases shared among large numbers of genes--are identified by a novel gene clustering approach based on the Akaike information criterion. Gene models derived from multiple "core" gene clusters are used to generate an artificial genome that models the properties of a genuine genome. Chimeric artificial genomes--representing those having experienced lateral gene transfer--were created by combining genes from multiple artificial genomes, and the performance of the parametric methods for identifying "atypical" genes was assessed directly. We found that a hidden Markov model that included multiple gene models, each trained on sets of genes representing the range of genotypic variability within a genome, could produce artificial genomes that mimicked the properties of genuine genomes. Moreover, different methods for detecting foreign genes performed differently--i.e., they had different sets of strengths and weaknesses--when identifying atypical genes within chimeric artificial genomes.

Algorithms↗
PubMed2006

A new methodological approach to nonverbal behavior analysis in cultural perspective.

The measurement of human behavior is a complex task, both for psychologists and human sciences researchers and with respect to technology, since advanced and sophisticated instruments may have to be implemented to manage the plurality of variables involved. In this article, an observational study is presented in which a quantitative procedure, the external variables method (Duncan & Fiske, 1977), was integrated with a structural analysis (Magnusson, 1993, 2000) in order to detect the hidden organization of nonverbal behavior in Italian and Icelandic interactions. To this aim, Theme software was introduced and employed. The results showed that both the frequency and the typology of gestures deeply change as a function of culture. Moreover, a high number of patterns was detected in both Italian and Icelandic interactions: They appeared to be complex sequences in which a huge number of events were constantly happening and recurring. In this domain, Theme software provides a methodological progression from the quantitative to the structural approach.

Adult↗
PubMed2002

Predicting the presence of acute pulmonary embolism: a comparative analysis of the artificial neural network, logistic regression, and threshold models.

OBJECTIVE: The objective of this study was to determine whether an artificial neural network, a new data analysis method, offers increased performance over conventional logistic regression in predicting the presence of a pulmonary embolism for patients in a well-known data set. MATERIALS AND METHODS: Data from the 1064 patients who received an angiographically based diagnosis of pulmonary embolism in the Prospective Investigation of Pulmonary Embolism Diagnosis study were encoded using a previously described method. The 21 input variables represented abnormalities identified on each patient's ventilation-perfusion scan and chest radiograph. Two methods-an artificial neural network with one hidden layer and a multivariate logistic regression-were compared for accuracy in predicting the presence or absence of pulmonary embolism on subsequent pulmonary arteriography. RESULTS: No significant difference was observed between the two methods. Areas under the receiver operating characteristic curves +/- standard deviation were 0.78 +/- 0.02 for the artificial neural network model and 0.79 +/- 0.02 for the logistic regression model. Furthermore, use of these two methods resulted in no more diagnostic accuracy than did the use of a simple threshold model based only on the number of subsegmental perfusion defects, which was the dominant input variable. CONCLUSION: In the study population, the usefulness of data from ventilation-perfusion scans as predictors of the presence of a pulmonary embolism was similar for the three analytic methods, a finding that reinforces the importance of making comparisons to simpler or more established methods when performing studies involving complex analytic models, such as artificial neural networks.

Acute Disease↗
PubMed2005

Hidden pathologies associated with (and concealed by) early gestational isolated fetal hydrothorax.

Isolated fetal hydrothorax is an uncommon finding on routine prenatal ultrasound and is associated with a variable prognosis. We believe this is the first report of a patient whose antenatal hydrothorax was associated with both congenital diaphragmatic hernia and congenital pulmonary lymphangiectasia. This rare combination caused significant problems in diagnosis and subsequent treatment.

Diagnosis, Differential↗
PubMed2004

Variability and heritability of cell division pathways in Toxoplasma gondii.

A histone 2b-YFP fusion protein stably expressed in Toxoplasma gondii has several advantages: it reveals previously hidden details of nuclear morphology; it makes it possible to observe cell-cycle events; it provides a basis for quantitative measurements of DNA content in living cells; and it enables sorting of live cells according to cell-cycle phase or ploidy. With this cell line it was possible to recognize and directly clone individual progeny arising from different patterns of cell division that produce two, three or four daughter cells. These experiments established that the progeny produced by all cell division pathways are viable and infective. Furthermore, the number of progeny produced by a mature parasite during cell division is not correlated with the number of its siblings. The complete repertoire of cell division pathways is therefore inherited by a single cell produced through any one of the individual paths. The results expand the range of what must be considered normal in T. gondii cell division and provide a useful tool for further study of nuclear structure and proliferation in this important human pathogen.

Animals↗
PubMed2006

Improvement of bioprocess monitoring: development of novel concepts.

The advancement of bioprocess monitoring will play a crucial role to meet the future requirements of bioprocess technology. Major issues are the acceleration of process development to reduce the time to the market and to ensure optimal exploitation of the cell factory and further to cope with the requirements of the Process Analytical Technology initiative. Due to the enormous complexity of cellular systems and lack of appropriate sensor systems microbial production processes are still poorly understood. This holds generally true for the most microbial production processes, in particular for the recombinant protein production due to strong interaction between recombinant gene expression and host cell metabolism. Therefore, it is necessary to scrutinise the role of the different cellular compartments in the biosynthesis process in order to develop comprehensive process monitoring concepts by involving the most significant process variables and their interconnections. Although research for the development of novel sensor systems is progressing their applicability in bioprocessing is very limited with respect to on-line and in-situ measurement due to specific requirements of aseptic conditions, high number of analytes, drift, and often rather low physiological relevance. A comprehensive survey of the state of the art of bioprocess monitoring reveals that only a limited number of metabolic variables show a close correlation to the currently explored chemical/physical principles. In order to circumvent this unsatisfying situation mathematical methods are applied to uncover "hidden" information contained in the on-line data and thereby creating correlations to the multitude of highly specific biochemical off-line data. Modelling enables the continuous prediction of otherwise discrete off-line data whereby critical process states can be more easily detected. The challenging issue of this concept is to establish significant on-line and off-line data sets. In this context, online sensor systems are reviewed with respect to commercial availability in combination with the suitability of offline analytical measurement methods. In a case study, the aptitude of the concept to exploit easily available online data for prediction of complex process variables in a recombinant E. coli fed-batch cultivation aiming at the improvement of monitoring capabilities is demonstrated. In addition, the perspectives for model-based process supervision and process control are outlined.

Journal Article↗
PubMed2006

Controlled amine functionality in self-assembled monolayers via the hidden amine route: chemical and electronic tunability.

A synthetic strategy for fabricating a dense amine functionalized self-assembled monolayer (SAM) on hydroxylated surfaces is presented. The assembly steps are monitored by X-ray photoelectron spectroscopy, Fourier transform infrared- attenuated total reflection, atomic force microscopy, variable angle spectroscopic ellipsometry, UV-vis surface spectroscopy, contact angle wettability, and contact potential difference measurements. The method applies alkylbromide-trichlorosilane for the fabrication of the SAM followed by surface transformation of the bromine moiety to amine by a two-step procedure: S(N)2 reaction that introduces the hidden amine, phthalimide, followed by the removal of the protecting group and exposing the free amine. The use of phthalimide moiety in the process enabled monitoring the substitution reaction rate on the surface (by absorption spectroscopy) and showed first-order kinetics. The simplicity of the process, nonharsh reagents, and short reaction time allow the use of such SAMs in molecular nanoelectronics applications, where complete control of the used SAM is needed. The different molecular dipole of each step of the process, which is verified by DFT calculations, supports the use of these SAMs as means to tune the electronic properties of semiconductors and for better synergism between SAMs and standard microelectronics processes and devices.

Journal Article↗
PubMed2001

Reply to: Econometric issues in testing the age neutrality of health care expenditure.

Salas and Raftery allege that in our paper, (1) remaining life expectancy is an endogenous explanatory variable of health care expenditure and (2) the parameter designed to correct for sample selection bias in fact represents a hidden relationship between health care expenditure and age. We argue that claim (1) is not supported by the available empirical evidence, while claim (2) seems to derive from a too cursory reading of our paper.

Age Factors↗
PubMed2000

Fraser-cryptophthalmos syndrome.

Fraser or Cryptophthalmos syndrome is a variable syndrome to the extent that cryptophthalmos might not be present in all cases. However, the main features are a "hidden eye", other craniofacial abnormalities, renal abnormalities, syndactyly and abnormal genitalia. It may be classified as isolated cryptophthalmos or cryptophthalmos sequence and cryptophthalmos syndrome. The cryptophthalmos syndrome has an autosomal recessive mode of inheritance. Isolated cryptophthalmos has been reported as an autosomal dominant trait. Prenatal diagnosis is possible using ultrasonography and fetoscopy. We report three cases of cryptophthalmos. One with renal agenesis had cryptophthalmos syndrome and the other two had isolated cryptophthalmos or cryptophthalmos sequence.

Abnormalities, Multiple↗
PubMedDate not supplied

Predicting hypogonadism in men based upon age, presence of erectile dysfunction, and depression.

Hypogonadism, a disorder associated with aging, can cause significant morbidity. As clinical manifestations of hypogonadism can be subtle, the challenge and the burden of diagnosis remain the responsibility of the clinician. Four different analytic methods were used to predict hypogonadism in men based upon age, the presence of erectile dysfunction (ED) and depression. 218 men were classified by age, serum testosterone level, the presence of ED and depression. Depression was determined by the Center for Epidemiologic Studies Depression Scale (CES-D). ED was assessed by the Sexual Health Inventory for Men (SHIM). Hypogonadism was defined as a serum testosterone level <300 ng/dl. An artificial neural network (ANN) was programmed and trained to predict hypogonadism based upon age, SHIM, and CES-D scores. Subject data was randomly partitioned into a training set of 148 (67.9%) and a test set of 70 (32.1%). The ANN processed the test set only after the training was complete. The discrete predicted binary output was set to (0) if testosterone level was <300 ng/dl or (1) if >300 ng/dl. The data was also analyzed by standard logistic regression (LR), linear and quadratic discriminant function analysis (LDFA and QDFA, respectively). Reverse regression (RR) analysis evaluated the statistical significance of each risk factor. The ANN can accurately predict hypogonadism in men based upon age, the presence of ED, and depression (receiver-operating characteristic=0.725). A four hidden node network was found to have the highest accuracy. RR revealed the depression index score to be most significant variable (P=0.0019), followed by SHIM score (P=0.00602), and then by age (P=0.015). Hypogonadism can be predicated by an ANN using the input factors of age, ED, and depression. This model can help clinicians assess the need for endocrinologic evaluation in men.

Adolescent↗