Debugging and Testing Optimizers through Comparison Checking

We present a novel technique called comparison checking that helps optimizer writers debug optimizers by testing, for given inputs, that the semantics of a program are not changed by the application of optimizations. We have successfully applied comparison checking to a large class of program transformations that alter (1) the relative ordering in which values are computed by the intermediate code statements, (2) the form of the intermediate code statements, and (3) the control flow structure using code replication. We outline the key steps that lead to the automation of comparison checking. The application of comparison checking to test the implementations of high level loop transformations, low level code optimizations, and global register allocation for given program inputs is then described.     

Typed Mobile Ambients in Maude

Maude has revealed itself as a powerful tool for implementing different kinds of semantics so that quick prototypes are available for trying examples and proving properties. In this paper we show how to define in Maude two semantics for Cardelli and Gordon's Ambient Calculus. The first one is the operational (reduction) semantics which requires the definition of Maude strategies in order to avoid infinite loops. The second one is a type system defined by Cardelli and Gordon to avoid communication errors. The correctness of that system was not formally proved. We enrich the operational semantics with error rules and prove that well-typed processes do not produce such errors. The type system is highly non-deterministic. We show here one possible way of implementing such non-determinism in the rules.     

Solute-solvent interactions in micellar electrokinetic chromatography. 6. Optimization of the selectivity of lithium dodecyl sulfate-lithium perfluorooctanesulfonate mixed micellar buffers

The optimization of the composition of mixed surfactants used as micellar electrokinetic chromatography (MEKC) pseudostationary phases is proposed as an effective method for the separation of complex mixtures of analytes. The solvation parameter model is used to select two surfactants (lithium dodecyl sulfate, LDS, and lithium perfluorooctanesulfonate, LPFOS) with contrasting solvation properties. Combination of these two surfactants allows variations of the solvation properties of MEKC pseudostationary phase along a wide range. Thus, the convenient variation of the proportion of both surfactants allows an effective control of the selectivity in such systems. An algorithm that predicts the overall resolution of a given mixture of compounds is described and applied to optimize the composition of the mixed surfactant for the separation of the mixture. The algorithm is based on the calculation of peak purities on simulated chromatograms as a function of the composition of the mixed LDS/LPFOS micellar buffer from data at several micellar buffer compositions. Successful separations were achieved for mixtures containing up to 20 compounds, in less than 12 min.     

The myosin coiled-coil is a truly elastic protein structure

Coiled-coils occur in a variety of proteins involved in mechanical and structural tasks in the cell. Their mechanical properties are important in various contexts ranging from hair elasticity to synaptic fusion. Beyond their importance in biology, coiled-coils have also attracted interest as programmable protein sequences for the design of novel hydrogels and materials. We have studied the elastic properties of the myosin coiled-coil at the single molecule level. The coiled-coil undergoes a massive structural transition at forces between 20 and 25 pN where the coil extends to about 2.5 times its original length. Unlike all other proteins investigated mechanically so far, this transition is reversible on a timescale of less than a second, making the coiled-coil a truly elastic protein.     

Effect of ultrafiltration on placental‐fetal blood flow in pregnancy of woman undergoing chronic hemodialysis

Introduction: Patient who was undergoing hemodialysis (HD) thrice weekly usually gain 1 to 4 kg of weight in interdialytic period, mainly due to fluid accumulation by ingestion of water. Ultrafiltration (UF) during HD will be need to remove fluid excess to avoid severe medical complications secondary to fluid overload. However, in pregnant woman UF can increase the episodes of intradialytic hypotension which may lead to placental ischemic injury and predispose to fetal distress. There is little information about safe fluid amount withdrawn by UF during pregnancy. Methods: We prospectively study by obstetric Doppler ultrasonography the fluxometric parameters: pulsatility index (PI) and resistance index (RI) of fetal middle cerebral, uterine, and umbilical artery obtained at the beginning and the end of HD session, the acute and chronic effect of UF on placenta and fetus blood flow, as well as the fetal outcome in 1 pregnant woman on chronic HD. Findings: We did not observe any acute harmful effect on fetal middle cerebral, placental and umbilical artery blood flow when UF rate of 2.1 ± 0.04 L (6 < 8 mL/h/kg) during HD session, no significant statistical difference was observed when compared PI and RI before and after UF and also when we compared these data with reference value on normal pregnancy to the same gestational age. Discussion: UF rate of 6 < 8 mL/h/kg during HD did not bring any acute harmful effect on fetal middle cerebral, placental, and umbilical blood flow and the UF rate of 1.4 6 0.4 L (< 6 mL/h/kg) / HD session that was done in all others HD during pregnancy was safe, without any chronic fetal deleterious effect. Obstetric Doppler ultrasonography is a simple and noninvasive method to fetal follow‐up and can aid to determine safe UF rate in pregnant women during gestation.     

Retrieval of leaf chlorophyll content in field crops using narrow-band indices: effects of leaf area index and leaf mean tilt angle

Reliable estimation of leaf chlorophyll-a and -b content (chl-a + b) at canopy scales is essential for monitoring vegetation productivity, physiological stress, and nutrient availability. To achieve this, narrow-band vegetation indices (VIs) derived from imaging spectroscopy data are commonly used. However, VIs are affected by canopy structures other than chl-a + b, such as leaf area index (LAI) and leaf mean tilt angle (MTA). In this study, we evaluated the performance of 58 VIs reported in the literature to be chl-a + b-sensitive against a unique measured set of species-specific leaf angles for six crop species in southern Finland. We created a large simulated canopy reflectance database (100,000 canopy configurations) using the physically based PROSAIL (coupling of PROSPECT and SAIL (Scattering by Arbitrarily Inclined Leaves) radiative transfer models) model. The performance of model-simulated indices was compared against airborne AISA Eagle II imaging spectroradiometer data and field-measured chl-a + b, LAI, and MTA values. In general, LAI had a positive effect on the strength of the correlation between chl-a + b and VIs while MTA had a negative effect in both measured and simulated data. Three indices (REIP (red edge inflection point), TCARI (transformed chlorophyll absorption ratio index)/OSAVI (optimized soil-adjusted vegetation index), and CTR6 (Carter indices)) showed strong correlations with chl-a + b and similar performance in model-simulated and measured data set. However, only two (TCARI/OSAVI and CTR6) were independent from LAI and MTA. We consider these two indices robust proxies of crop leaf chl-a + b.     

Supervisor Perspective on the Process and Outcome of Giving Easy, Difficult, or No Feedback to Supervisees.

Fifteen counseling center supervisors were interviewed about 3 instances related to important feedback with an intern supervisee: 1 in which the feedback was given easily, 1 in which it was given reluctantly or with difficulty, and another in which it was not given. Supervisors indicated that easy feedback was most often about clinical problems, was given directly, had positive effects, and was facilitated by supervisee openness. Difficult feedback was most often about clinical, personal, and professional issues, was given indirectly, had mixed impact, and was characterized by a lack of supervisee openness. Feedback not given was typically about personal and professional concerns and was hindered by a lack of supervisee openness. Supervisors indicated that there were negative effects of not having given the feedback and indicated that they would do it differently if they could. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Client and Counselor Trainee Attachment as Predictors of Session Evaluation and Countertransference Behavior in First Counseling Sessions.

This study investigated client and counselor trainee attachment as predictors of session evaluation and countertransference behavior in 93 first counseling sessions. Results indicated that client attachment predicted aspects of session evaluation, whereas counselor attachment and the interaction of client and counselor attachment predicted aspects of countertransference. Specifically, client fearful attachment was negatively associated with client ratings of session smoothness and depth and with counselor ratings of session smoothness. Counselor dismissing attachment was positively associated with supervisor ratings of hostile countertransference. Furthermore, interactions between client and counselor attachment predicted hostile and distancing countertransference reactions, such that countertransference was highest when the client had a preoccupied attachment pattern and the counselor trainee had a fearful or dismissing attachment pattern. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An approximate algorithm for top-k closest pairs join query in large high dimensional data

In this paper we present a novel approximate algorithm to calculate the top-k closest pairs join query of two large and high dimensional data sets. The algorithm has worst case time complexity and space complexity and guarantees a solution within a factor of the exact one, where t  {1, 2, … , ∞} denotes the Minkowski metrics L_t of interest and d the dimensionality. It makes use of the concept of space filling curve to establish an order between the points of the space and performs at most d + 1 sorts and scans of the two data sets. During a scan, each point from one data set is compared with its closest points, according to the space filling curve order, in the other data set and points whose contribution to the solution has already been analyzed are detected and eliminated. Experimental results on real and synthetic data sets show that our algorithm behaves as an exact algorithm in low dimensional spaces; it is able to prune the entire (or a considerable fraction of the) data set even for high dimensions if certain separation conditions are satisfied; in any case it returns a solution within a small error to the exact one.     

This paper was incompletely published in Topics in Catalysis Volume 3 (1996) pp. 387–406. The complete version is printed below.

The thermal stability of the Wells–Dawson heteropoly compound K₆P₂W₁₈O₆₂·10H₂O was examined under both reducing and oxidizing conditions, and its structural and morphological evolution was characterized by several complementary solid state techniques. It is shown that the primary structure of the title compound remains intact up to 770 K, while at higher temperature structural changes and rearrangements are observed. These modifications depend considerably on the treatment conditions and catalyst composition. Under oxidizing conditions the Wells–Dawson compound rearranges with formation of a mixed phase containing the Keggin-type unit K₃PW₁₂O₄₀ and the hexatungstate K₂W₆O₁₉. Furthermore, the catalytic activity in the oxidation of isobutane is affected considerably by these changes. The best catalytic performance was shown by the rearranged Wells–Dawson compound. This revised version was published online in June 2006 with corrections to the Cover Date.