Estratègies i errors en la resolució de problemes d'extrems per mètodes elementals

Aquesta investigació s’engloba dins del camp de la resolució de problemes en educació matemàtica i se centra en estudiar de quina manera els alumnes de primer curs de Batxillerat de dos instituts públics de Catalunya resolen alguns problemes d’extrems per mètodes elementals, és a dir, sense utilitzar les tècniques del càlcul diferencial. Tanmateix, s’estudia el punt de partida d’aquests alumnes davant dels problemes de màxims i mínims i es detecten algunes estratègies i diversos errors que cometen a l’hora de resoldre’ls. L’instrument de recollida de dades és un qüestionari individual que combina problemes d’extrems de resposta tancada amb altres problemes de resposta oberta. Es realitza una anàlisi inductiva – deductiva de les dades, la qual permet determinar que una part important dels participants en la recerca confonen les relacions entre l’àrea i el volum d’algunes figures geomètriques. A més, la majoria dels alumnes d’aquesta investigació resolen els problemes d’extrems plantejats fent ús de l’estratègia de conjecturar. Finalment, es detecta que diverses respostes dels participants presenten errors causats per l’ús de teoremes i/o de definicions matemàtiques equivocades. Aquest és el cas d’una aplicació errònia del teorema de Pitàgores, la confusió del perímetre d’un quadrat amb la longitud del seu costat i la determinació incorrecta de l’altura de diversos paral·lelograms.

Relative clauses in Iraqi Arabic and the status of resumptive pronouns

Not much has been said about the grammar of Iraqi Arabic. This research is an attempt to shed light on the nature of IA relative clauses. The research focuses on the behavior of the resumptive strategy as opposed to the gap strategy. We consider islandhood, Weak and Strong CrossOver, reconstruction and scope binding, in order to further understand the behavior of resumption. The final conclusion reached is that in Iraqi Arabic the resumptive strategy is actually related to the gap strategy in several respects; and in those where it differs we propose that gaps (traces) are replaced by trace+pronoun complex

Inferring ultraviolet anatomical exposure patterns while distinguishing the relative contribution of radiation components

Exposure to solar ultraviolet (UV) radiation is the main causative factor for skin cancer. UV exposure depends on environmental and individual factors, but individual exposure data remain scarce. While ground UV irradiance is monitored via different techniques, it is difficult to translate such observations into human UV exposure or dose because of confounding factors. A multi-disciplinary collaboration developed a model predicting the dose and distribution of UV exposure on the basis of ground irradiation and morphological data. Standard 3D computer graphics techniques were adapted to develop a simulation tool that estimates solar exposure of a virtual manikin depicted as a triangle mesh surface. The amount of solar energy received by various body locations is computed for direct, diffuse and reflected radiation separately. Dosimetric measurements obtained in field conditions were used to assess the model performance. The model predicted exposure to solar UV adequately with a symmetric mean absolute percentage error of 13% and half of the predictions within 17% range of the measurements. Using this tool, solar UV exposure patterns were investigated with respect to the relative contribution of the direct, diffuse and reflected radiation. Exposure doses for various body parts and exposure scenarios of a standing individual were assessed using erythemally-weighted UV ground irradiance data measured in 2009 at Payerne, Switzerland as input. For most anatomical sites, mean daily doses were high (typically 6.2-14.6 Standard Erythemal Dose, SED) and exceeded recommended exposure values. Direct exposure was important during specific periods (e. g. midday during summer), but contributed moderately to the annual dose, ranging from 15 to 24% for vertical and horizontal body parts, respectively. Diffuse irradiation explained about 80% of the cumulative annual exposure dose.

Training effects with the observer-rated cognitive errors and the coping action patterns scales

The use of observer-rated scales requires that raters be trained until they have become reliable in using the scales. However, few studies properly report how training in using a given rating scale is conducted or indeed how it should be conducted. This study examined progress in interrater reliability over 6 months of training with two observer-rated scales, the Cognitive Errors Rating Scale and the Coping Action Patterns Rating Scale. The evolution of the intraclass correlation coefficients was modeled using hierarchical linear modeling. Results showed an overall training effect as well as effects of the basic training phase and of the rater calibration phase, the latter being smaller than the former. The results are discussed in terms of implications for rater training in psychotherapy research.

A-8a 2003 Summary of Food Stamp Errors - Active and Negative Cases, April 2003 - September 2003

Summary of food stamp errors.

A comparison between joint coordinate system and attitude vector for multi-segment foot kinematics.

The joint angles of multi-segment foot models have been primarily described using two mathematical methods: the joint coordinate system and the attitude vector. This study aimed to determine whether the angles obtained through these two descriptors are comparable, and whether these descriptors have similar sensitivity to experimental errors. Six subjects walked eight times on an instrumented walkway while the joint angles among shank, hindfoot, medial forefoot, and lateral forefoot were measured. The angles obtained using both descriptors and their sensitivity to experimental errors were compared. There was no overall significant difference between the ranges of motion obtained using both descriptors. However, median differences of more than 6° were noticed for the medial-lateral forefoot joint. For all joints and rotation planes, both descriptors provided highly similar angle patterns (median correlation coefficient: R>0.90), except for the medial-lateral forefoot angle in the transverse plane (median R=0.77). The joint coordinate system was significantly more sensitive to anatomical landmarks misplacement errors. However, the absolute differences of sensitivity were small relative to the joints ranges of motion. In conclusion, the angles obtained using these two descriptors were not identical, but were similar for at least the shank-hindfoot and hindfoot-medial forefoot joints. Therefore, the angle comparison across descriptors is possible for these two joints. Comparison should be done more carefully for the medial-lateral forefoot joint. Moreover, despite different sensitivities to experimental errors, the effects of the experimental errors on the angles were small for both descriptors suggesting that both descriptors can be considered for multi-segment foot models.

Variability of the relative afferent pupillary defect.

PURPOSE: Afferent asymmetry of visual function is detectable in both normal and pathologic conditions. With a computerized test, we assessed the variability in measuring afferent asymmetry of the pupillary light reflex, that is, the relative afferent pupillary defect. METHODS: In ten normal subjects, pupillary responses to an alternating light stimulus were recorded with computerized infrared pupillography. The relative afferent pupillary defect for each test was determined by using a new computer analysis. The 95% confidence interval of each determination of relative afferent pupillary defect was used to represent the short-term fluctuation in its measurement. To optimize the test for clinical use, we studied the influence of stimulus intensity, duration, and number on the variability of the relative afferent pupillary defect. RESULTS: When the relative afferent pupillary defect was based on only a few light alternations (stimulus pairs), there was excessive variability in its measurement (95% confidence interval > 0.5 log units). With approximately 200 stimulus pairs, the 95% confidence interval was reduced to less than 0.1 log unit (relative afferent pupillary defect +/- 0.05 log unit). Also, there was less variability when the dark interval between alternating light stimulation was less than one second. CONCLUSIONS: Computerized infrared pupillography can standardize the alternating light test and minimize the error in quantifying a relative afferent pupillary defect. A reproducible relative afferent pupillary defect measurement is desirable for defining afferent injury and following the course of disease.

Ab initio benchmark study for the oxidative addition of CH4 to Pd: importance of basis-set flexibility and polarization

To obtain a state-of-the-art benchmark potential energy surface (PES) for the archetypal oxidative addition of the methane C-H bond to the palladium atom, we have explored this PES using a hierarchical series of ab initio methods (Hartree-Fock, second-order Møller-Plesset perturbation theory, fourth-order Møller-Plesset perturbation theory with single, double and quadruple excitations, coupled cluster theory with single and double excitations (CCSD), and with triple excitations treated perturbatively [CCSD(T)]) and hybrid density functional theory using the B3LYP functional, in combination with a hierarchical series of ten Gaussian-type basis sets, up to g polarization. Relativistic effects are taken into account either through a relativistic effective core potential for palladium or through a full four-component all-electron approach. Counterpoise corrected relative energies of stationary points are converged to within 0.1-0.2 kcal/mol as a function of the basis-set size. Our best estimate of kinetic and thermodynamic parameters is -8.1 (-8.3) kcal/mol for the formation of the reactant complex, 5.8 (3.1) kcal/mol for the activation energy relative to the separate reactants, and 0.8 (-1.2) kcal/mol for the reaction energy (zero-point vibrational energy-corrected values in parentheses). This agrees well with available experimental data. Our work highlights the importance of sufficient higher angular momentum polarization functions, f and g, for correctly describing metal-d-electron correlation and, thus, for obtaining reliable relative energies. We show that standard basis sets, such as LANL2DZ+ 1f for palladium, are not sufficiently polarized for this purpose and lead to erroneous CCSD(T) results. B3LYP is associated with smaller basis set superposition errors and shows faster convergence with basis-set size but yields relative energies (in particular, a reaction barrier) that are ca. 3.5 kcal/mol higher than the corresponding CCSD(T) values

Opinion de Marbot, membre du Conseil des Anciens, sur la résolution relative au complément de deux cent mille conscrits : séance du 28 germinal an 7 ([Reprod.]) / [Conseil des Anciens]

Collection : Les archives de la Révolution française ; 11.1a.128

Validation study of the French version of the observer-rater scales measuring coping and cognitive errors (CE-CAP) on a non-clinical population

This study examined the validity and reliability of the French version of two observer-rated measures developed to assess cognitive errors (cognitive errors rating system [CERS]) [6] and coping action patterns (coping action patterns rating system [CAPRS]) [22,24]. The CE measures 14 cognitive errors, broken down according to their valence positive or negative (see the definitions by A.T. Beck), and the CAP measures 12 coping categories, based on an comprehensive review literature, each broken down into three levels of action (affective, behavioural, cognitive). Thirty (N = 30) subjects recruited in a community sample participated in the study. They were interviewed according to a standardized clinical protocol: these interviews were transcribed and analysed with both observer-rated systems. Results showed that the inter-rater reliability of the two measures is good and that their internal validity is satisfactory, due to a non-significant canonical correlation between CAP and CE. With regard to discriminant validity, we found a non-significant canonical correlation between CAPRS and CISS, one of most widely used self-report questionnaire measuring coping. The same can be said for the correlation with a self-report questionnaire measuring symptoms (SCL-90-R). These results confirm the absence of confounds in the assessment of cognitive errors and of coping as assessed by these observer-rated scales and add an argument in favour of the French validation of the CE-CAP rating scales. (C) 2010 Elsevier Masson SAS. All rights reserved.