Relative Efficacies Research Articles

Structural Determinants of d-Cycloserine Efficacy at the NR1/NR2C NMDA Receptors

We have studied relative efficacies of NR1 agonists glycine and d-cycloserine (DCS), and found efficacy to be dependent on the NR2 subunit. DCS shows partial agonism at NR1/NR2B but has higher relative efficacy than glycine at NR1/NR2C receptor. Molecular dynamics (MD) simulations of the NR1/NR2B and NR1/NR2C agonist binding domain dimer suggest only subtle differences in the interactions of DCS with NR1 binding site residues relative to glycine. The most pronounced differences were observed in the NR1/NR2C simulation between the orientation of helices F and G of the NR1 subunit. Interestingly, Helix F was previously proposed to influence receptor gating and to adopt an orientation depending on agonist efficacy. MD simulations and site-directed mutagenesis further suggest a role for residues at the agonist binding domain dimer interface in regulating DCS efficacy. To relate the structural rearrangements to receptor gating, we recorded single-channel currents from outside-out patches containing a single active NR1/NR2C receptor. DCS increased the mean open time and open probability of NR1/NR2C receptors compared with glycine. Maximum likelihood fitting of a gating model for NR1/NR2C receptor activation to the single-channel data suggests that DCS specifically accelerates the rate constant governing a fast gating step and reduces the closing rate. These changes appear to reflect a decreased activation energy for a pregating step and increased stability of the open states. We suggest that the higher efficacy of DCS at NR1/NR2C receptors involves structural rearrangements at the dimer interface and an effect on NR1/NR2C receptor pregating conformational changes.

Full implementation and benchmark studies of Mukherjee’s state-specific multireference coupled-cluster ansatz

The state-specific multireference coupled-cluster (SS-MRCC) ansatz developed by Mukherjee and co-workers [J. Chem. Phys. 110, 6171 (1999)] has been implemented by means of string-based techniques. The implementation is general and allows for using arbitrary complete active spaces of any spin multiplicity and arbitrarily high excitations in the cluster operators. Several test calculations have been performed for single- and multiple-bond dissociations of molecular systems. Our experience shows that convergence problems are encountered when solving the working equations of the SS-MRCC in the case the weight of one or more reference functions tends to take on very small values. This is system specific and cannot yet be handled in a black-box fashion. The problem can be obviated by either dropping all the cluster amplitudes from the corresponding model functions with coefficients below a threshold or by a regularization procedure suggested by Tikhonov or a combination of both. In the current formulation the SS-MRCC is not invariant with respect to transformation of active orbitals among themselves. This feature has been extensively explored to test the degree of accuracy of the computed energies with both pseudocanonical and localized active orbitals. The performance of the method is assessed by comparing the results with the corresponding full configuration interaction (CI) values with the same set of orbitals (correlated and frozen). Relative efficacies of CI methods such as MRCI singles and doubles with the same active space and size-extensivity corrected ones such as MR averaged coupled pair functional and MR averaged quadratic CC have also been studied. Allied full-fledged CC methods have also been employed to see their relative performance vis-à-vis the SS-MRCC. These latter methods are the complete-active-space-inspired single-reference (SR) CC based SS theory and the single-root MR Brillouin-Wigner CC. Our benchmark results indicate that the performance of the SS-MRCC is generally quite good for localized active orbitals. The performance with the pseudocanonical orbitals, however, is sometimes not as satisfactory as for the localized orbitals.

Organizational stress, psychological strain, and work outcomes in six national contexts

PurposeThe purpose of this paper is to investigate the moderating roles of two distinct styles of coping and decision latitude on the relationship between three facets of role stress and psychological strain in six national contexts.Design/methodology/approachThe objective of the research is to examine the relative predictive efficacies of three theory specific moderators in six countries which differ on the cultural dimension of individualism‐collectivism. The data are analyzed using moderated regression analysis.FindingsThe results show that problem‐focused coping is a better moderator in the individualistic countries and that emotion‐focused coping is a better moderator in the collectivistic contexts. None of the three moderators moderate the relationships in Germany and South Africa – the two countries which had scores in the mid‐range of the individualism‐collectivism continuum. Findings are discussed for their significance into the interplay of cultural variations and coping with work stress in predicting psychological strain or distress on the job.Practical implicationsPractical implications for managing human resources in various subsidiaries of multinational and global organizations are discussed.Originality/valueThis paper confirms existing theories and expands the authors’ understanding of role stress and psychological strain in different cultural contexts.

Kinetic characterization and comparison of various protein crosslinking reagents for matrix modification

We have characterized the relative efficacies of a number of protein crosslinking agents that have the potential for use in the crosslinking of proteinaceous matrices both in vitro and in vivo. The crosslinkers tested were; L: -threose (LT), Genipin (GP), Methylglyoxal (MG), 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC), proanthrocyanidin (PA) and glutaraldehyde (GA). The relative effectiveness of the crosslinkers with regard to their saturating concentrations was: GA > PA > EDC > MG = GP >> LT. Most of the crosslinkers displayed a pH dependence and were more effective at more alkaline pH. At optimal pH and saturating conditions, the relative reaction rates of the crosslinkers were: PA = GA > EDC > GP > MG >> LT.

Comparison of different immunoprophylaxis regimens after liver transplantation with hepatitis B core antibody-positive donors: A systematic review

Orthotopic liver transplantation (OLT) recipients without hepatitis B virus (HBV) infection who receive liver grafts from antibody to hepatitis B core antigen-positive [HBcAb(+)], hepatitis B surface antigen-negative [HBsAg(-)] donors have an increased risk of developing de novo hepatitis B infection. We compared the 2 most commonly employed prophylactic regimens-lamivudine (LAM) monotherapy and hepatitis B immunoglobulin (HBIG)+LAM combination therapy-to determine the relative efficacies of these 2 protocols in preventing de novo hepatitis B infection. A comprehensive search of the Cochrane Database of Systematic Reviews, MEDLINE (1966 to June 2009), and bibliographies of retrieved trials was conducted. Eligible studies included OLT recipients who received HBcAb(+) liver grafts and were treated prophylactically with either LAM monotherapy or HBIG+LAM combination therapy. 13 studies were identified as meeting the eligibility criteria. The rates of de novo hepatitis B infection, mortality, and mortality due to de novo hepatitis B infection were assessed. The incidence of de novo hepatitis B infection was 2.7% (n = 73) in patients receiving LAM-only prophylaxis versus 3.6% (n = 110) in patients receiving HBIG+LAM combination therapy. In the HBIG+LAM group, the dose and duration of HBIG therapy were highly variable. The median follow-up time for the LAM monotherapy group was 25.4 months with a range of 14.78 to 27.6 months, whereas the median follow-up time for the LAM+HBIG group was 31.1 months with a range of 15.3 to 38.5 months. The risk of developing de novo hepatitis B infection based on the pretransplant recipient HBV serology in each treatment group could not be calculated because of incomplete data and the limited number of de novo hepatitis B infection cases in the series reviewed. In conclusion, on the basis of these findings, we conclude that published studies have not shown HBIG+LAM combination therapy to be more effective than LAM-only treatment. Nucleoside analogue monotherapy should therefore be considered when one is treating HBV(-) patients who have received liver allografts from HBcAb(+) donors.

Relative effectiveness assessment of listed drugs (REAL): A new method for an early comparison of the effectiveness of approved health technologies

Post-listing assessment of pharmaceuticals depends on national habits. In England, the assessment is based on estimates of cost per quality-adjusted life-year. These are made some considerable time after listing (negative list). In France, effectiveness, and then efficiency, is assessed immediately after listing (positive list). We propose a new formal method--the REAL method--that can help make early comparisons of the effectiveness of medical treatments. Relative efficacies are first obtained from randomized controlled trials (RCTs). Members of the Transparency Committee (French National Authority for Health) are then consulted by questionnaire on the transposability of these results to real life. The RCT results and experts' ratings are entered into an effect model to obtain estimates of relative effectiveness, using unidimensional scaling, and bootstrap procedures. Application of the REAL method to the example of a new drug to treat Parkinson's disease and three comparators used in the same indication provided graphs of the distributions of their relative efficacy and relative effectiveness. The new drug was found to provide no added value. The REAL method is a rational, transparent, and practical procedure for comparing the effectiveness of pharmaceuticals in an immediate post-listing setting.

Diagnosis of pancreatic tumors by endoscopic ultrasonography

Pancreatic tumors are highly diverse, as they can be solid or cystic, and benign or malignant. Since their imaging features overlap considerably, it is often difficult to characterize these tumors. In addition, small pancreatic tumors, especially those less than 2 cm in diameter, are difficult to detect and diagnose. For characterizing pancreatic tumors and detecting small pancreatic tumors, endoscopic ultrasonography (EUS) is the most sensitive of the imaging procedures currently available. This technique also provides good results in terms of the preoperative staging of pancreatic tumors. EUS-guided fine needle aspiration (EUS-FNA) has also proved to be a safe and useful method for tissue sampling of pancreatic tumors. Despite these advantages, however, it is still difficult to differentiate between benign and malignant, solid or cystic pancreatic tumors, malignant neoplasms, and chronic pancreatitis using EUS, even when EUS-FNA is performed. Recently, contrast-enhanced EUS with Doppler mode (CE-EUS) employing ultrasound contrast agents, which indicate vascularization in pancreatic lesions, has been found to be useful in the differential diagnosis of pancreatic tumors, especially small pancreatic tumors. However, Doppler ultrasonography with contrast-enhancement has several limitations, including blooming artifacts, poor spatial resolution, and low sensitivity to slow flow. Consequently, an echoendoscope was developed recently that has a broad-band transducer and an imaging mode that was designed specifically for contrast-enhanced harmonic EUS (CEH-EUS) with a second-generation ultrasound contrast agent. The CEH-EUS technique is expected to improve the differential diagnosis of pancreatic disease in the future. This review describes the EUS appearances of common solid and cystic pancreatic masses, the diagnostic accuracy of EUS-FNA, and the relative efficacies and advantages of CE-EUS and CEH-EUS along with their relative advantages and their complementary roles in clinical practice.

Organizational stress, psychological strain, and work outcomes in six national contexts

Purpose – The purpose of this paper is to investigate the moderating roles of two distinct styles of coping and decision latitude on the relationship between three facets of role stress and psychological strain in six national contexts. Design/methodology/approach – The objective of the research is to examine the relative predictive efficacies of three theory specific moderators in six countries which differ on the cultural dimension of individualism-collectivism. The data are analyzed using moderated regression analysis. Findings – The results show that problem-focused coping is a better moderator in the individualistic countries and that emotion-focused coping is a better moderator in the collectivistic contexts. None of the three moderators moderate the relationships in Germany and South Africa – the two countries which had scores in the mid-range of the individualism-collectivism continuum. Findings are discussed for their significance into the interplay of cultural variations and coping with work stress in predicting psychological strain or distress on the job. Practical implications – Practical implications for managing human resources in various subsidiaries of multinational and global organizations are discussed. Originality/value – This paper confirms existing theories and expands the authors’ understanding of role stress and psychological strain in different cultural contexts.

Subunit-Specific Activation of NMDA Receptors

NMDA receptors are ligand-gated ion channels assembled from two NR1 and two NR2 subunits, and are activated upon simultaneous binding of glycine and glutamate to the NR1 and NR2 subunits, respectively. The different NR2 subunits (NR2A-D) endow the NMDA receptors with markedly different biophysical and pharmacological properties. We have focused on how the conformational changes that are induced by agonist binding and enable channel gating are specific for the NR2 subunit. For this purpose, we have developed a series of N-hydroxypyrazole-5-glycine (NHP5G) compounds that are partial agonists for the glutamate binding site of the NR2 subunit. This structurally related series of partial agonists show a broad range of relative efficacies at NR2 subunits and weakly activate the channel, allowing better identification of the steps associated with channel opening. Propyl-substituted NHP5G shows strong subunit selectivity in that it activates NR1/NR2D (37%), but does not appear to activate NR1/NR2A (∼0%).Single-channel recordings for NR1/NR2D expressed in HEK293 cells using partial agonists (NH5PG, ethyl-, and propyl-NH5PG) and the full agonist glutamate enable us to determine which states in the process of channel activation can be modulated in an agonist-specific manner. These data show that glutamate, NHP5G, ethyl-, and propyl-NH5PG have strikingly different mean open times for NR1/NR2D (0.747, 0.432, 0.319, and 0.181 ms, respectively). We are currently comparing the rate constants for activation in models fitted to data from different partial agonists. We have also performed molecular dynamics (MD) simulations of the agonist binding domains for NR1/NR2A and NR1/NR2D bound with glutamate or propyl-NHP5G to predict how the agonists interact differentially with receptor subtypes. The synthesis of these lines of investigation will be used to identify structural elements that can be modified using mutagenesis to test working hypotheses on the structural basis for subunit-specific activation of NMDA receptors.

Trapping mosquitoes using milk products as odour baits in western Kenya

BackgroundAmple evidence has shown that blood seeking mosquitoes locate their hosts by following odours produced by the hosts. Odour baited traps would therefore, provide a solution in controlling diseases spread by mosquitoes. Comparative studies were undertaken to determine the relative efficacies of two odour baits i.e. Limburger cheese and African traditional milk cream in trapping mosquitoes in the field in western Kenya.MethodComparative efficacy studies were carried out in the field using Latin square experimental designs. In the first study, a counterflow geometry (CFG) trap (MM-x model; American Biophysics Corp., USA.) baited with Limburger cheese, man landing catches (MLC), Centres for Disease Control (CDC) light trap and an entry trap were compared. In the second study, three CFG traps baited with either Limburger cheese, African traditional milk cream or with no bait were compared and in the third study four CDC traps baited with either Limburger cheese, African traditional milk cream, light or with no bait were compared. Parameters like species, catch size, abdominal status, parity status and size of the collected mosquitoes were compared.ResultsA total of 1,806 mosquitoes were collected (60% An. gambiae s.l and 25% An.funestus, culicines 15%). There was no significant difference in the number of An. funestus trapped by the CFG trap baited with Limburger cheese from those trapped by the MLC (P = 0.351). The Limburger cheese baited CFG trap collected significantly more gravid An. funestus than the MLC (P = 0.022). Furthermore, when the CFG trap baited with Limburger cheese and the CFG trap baited with milk cream were compared, there was no significant difference in the number of An. funestus collected (P = 0.573). The same trend was observed in the comparison of Limburger cheese baited CDC trap and milk cream baited CDC trap.ConclusionsLimburger cheese and African traditional milk cream have a potential as effective odour baits for sampling/surveillance and as oviposition attractants for the malaria vector, Anopheles funestus.

Clinical Evaluation of Type I Bovine Collagen in the Treatment of Localized Gingival Recession

ABSTRACTBackgroundOver the years, coronally advanced flap and the use of guided tissue regeneration have been among the more successful techniques in treating gingival recession. The present study compared the relative efficacies of these two techniques in treating gingival recession.MethodsTwelve patients presenting with localized identical anterior recessions were taken up in a split mouth design for the study. One site was randomly assigned to be treated with coronally advanced flap supported by membrane while the other was treated with coronally advanced flap alone. Changes in clinical parameters, such as recession width, recession depth, surface area of the recession defect, width of keratinized tissue, gingival status, probing pocket depth and clinical attachment level were measured at baseline and at 3 and 6 months postoperatively.ResultsIn the 10 patients that were followed up, both treatments resulted in a significant gain in root coverage amounting to a mean gain of 66.49% in the membrane group and 65.56% in the CAF group. The differences in root coverage and the clinical attachment level gains between the groups were not significant. However, significant gain in the width of keratinized tissue was seen in the membrane group after treatment.ConclusionThis study suggests that coronally advanced flap procedure provides a predictable, simple and convenient technique in the treatment of localized class I gingival recession. Combining this technique with the placement of a bioabsorbable membrane does not seem to improve the results. The addition of a membrane, however, increases the width of keratinized tissue.

Differential ability of novel attenuated targeted deletion mutants of Francisella tularensis subspecies tularensis strain SCHU S4 to protect mice against aerosol challenge with virulent bacteria: Effects of host background and route of immunization

Francisella tularensis subspecies tularensis is a highly virulent facultative intracellular pathogen of humans and a potential biological weapon. A live vaccine strain, F. tularensis LVS, was developed more than 50 years ago by pragmatic attenuation of a strain of the less virulent holarctica subspecies. LVS was demonstrated to be highly effective in human volunteers who were exposed to intradermal challenge with fully virulent subsp. tularensis, but was less effective against aerosol exposure. LVS faces regulatory hurdles that to date have prevented its licensure for general use. Therefore, a better defined and more effective vaccine is being sought. To this end we have created gene deletion mutants in the virulent subsp. tularensis strain and tested them for their ability to elicit a protective immune response against systemic or aerosol challenge with the highly virulent wild-type subsp. tularensis strain, SCHU S4. Both oral and intradermal (ID) primary vaccination routes were assessed in BALB/c and C3H/HeN mice as was oral boosting. One SCHU S4 mutant missing the heat shock gene, clpB, was significantly more attenuated than LVS whereas a double deletion mutant missing genes FTT0918 and capB was as attenuated as LVS. In general mice immunized with SCHU S4Δ clpB were significantly better protected against aerosol challenge than mice immunized with LVS. A single ID immunization of BALB/c mice with SCHU S4Δ clpB was at least as effective as any other regimen examined. Mice immunized with SCHU S4Δ 0918Δ capB were generally protected to a similar degree as mice immunized with LVS. A preliminary examination of immune responses to vaccination with LVS, SCHU S4Δ clpB, or SCHU S4Δ 0918Δ capB provided no obvious correlate to their relative efficacies.

Allografting Combined with Systemic FK506 Produces Greater Functional Recovery than Conduit Implantation in a Rat Model of Sciatic Nerve Injury

Implantation of allografts or nerve conduits has been used to promote regeneration following peripheral nerve injuries involving substantial axon loss. Both methods provide promising alternatives to autologous grafting and avoid donor site morbidity. We compared the relative efficacies of allografting versus conduit implantation in a rat model of sciatic nerve regeneration. Two rat strains (Lewis and Dark Agouti; n = 30) were employed. Unoperated animals served as controls (group I). Animals in groups II and III underwent left sciatic nerve resection over a distance of 15 mm; group II animals received implants of collagen type I conduits; and group III animals received allografts from the other rat strain and systemic low-dose (0.1 mg/kg/d) administration of FK506. Walking tracks were recorded after 4, 8, 12, and 16 weeks; nerve sections were stained for myelin basic protein after 16 weeks. Functional tests revealed significantly better recovery in group III animals compared with group II even though there was no significant difference in the extent of remyelination. Neither group achieved the functional or histomorphometric values of control animals. Improved functional recovery following allografting plus systemic FK506, in comparison with conduit implantation, underlines the importance of systemic administration of neurotrophic molecules for nerve regeneration.

Understanding the dynamics of neonicotinoid activity in the management of Bemisia tabaci whiteflies on poinsettias

The relative efficacies of registered label rates for foliar and soil drench treatments of imidacloprid and dinotefuran at preventing the establishment of Bemisia tabaci B biotype whitefly populations on newly infested poinsettia plants were evaluated. Pesticide levels within and on plant leaves were monitored for 10 weeks by ELISA and LC/MS in an effort to better understand the dynamics of neonicotinoid activity against this insect and to estimate insecticide concentrations needed to kill the nymphal and adult stages. While all treatments proved equally effective as a remedial measure for the control of the resident adult populations, thereby accomplishing the objective of foliar contact treatments, the dinotefuran soil drench application was the only treatment that provided multi-generational control of Bemisia populations.

Geometric Factors in the Processing of Fine Fiber by Fluid Shear and Heat Transfer

In this article, a synergistic approach encompassing numerical simulation and laboratory experimentation is used to identify the optimal geometry for the creation of fine fiber by the melt-blown process. The problem involves highly complex fluid flow and convective heat transfer. The fine fiber is created by the use of high-velocity, obliquely impinging air jets that stretch a polymer extrudate in the partially fluid state. High-temperature air is used to maintain the fluidity of the polymeric material as it exits the die. Four different geometrical configurations were investigated with regard to their capability of producing high fluid shear and high temperatures in the critical region just downstream of the emergence of the polymer extrudate from the tip of a die. The results of the numerical simulations provided a definitive conclusion about the relative efficacies of the four investigated geometrical configurations. The velocity and temperature profiles of the oblique jets were carefully documented to identify their decay with increasing downstream distance from the die tip. Velocity profile measurements were in excellent agreement with the numerical predictions, thereby validating the simulation model. Another major parameter of the study, in addition to the geometric-configuration issue, was the pressure difference responsible for setting the magnitude of the jet velocity. The accuracy of the results was established by a mesh independence study and by varying the size of the solution domain.

Genetic Deletion of p90 Ribosomal S6 Kinase 2 Alters Patterns of 5-Hydroxytryptamine2A Serotonin Receptor Functional Selectivity

The concept of functional selectivity has now thoroughly supplanted the previously entrenched notion of intrinsic efficacy by explaining how agonists and antagonists exhibit a range of efficacies for distinct receptor-mediated responses. It is noteworthy that functional selectivity accommodates significant changes in efficacy resulting from differential expression of G protein-coupled receptor modifying proteins (i.e., "conditional efficacy")-a phenomenon with profound implications for drug discovery. We have uncovered a novel regulatory mechanism whereby p90 ribosomal S6 kinase 2 (RSK2) interacts with 5-hydroxytryptamine(2A) (5-HT(2A)) serotonin receptors and attenuates receptor signaling via direct receptor phosphorylation (Proc Natl Acad Sci U S A 103:4717-4722, 2006; J Biol Chem 284:5557-5573, 2009). This discovery, together with the mounting evidence for conditional efficacy, suggested to us that 5-HT(2A) agonist signaling might be disproportionately affected by alterations in RSK2 expression. To test this hypothesis, we evaluated a chemically diverse set of 5-HT(2A) agonists at three readouts of 5-HT(2A) receptor activation in both wild-type (WT) and RSK2 knock-out (KO) mouse embryonic fibroblasts (MEFs). Here we report that 5-HT(2A) receptor agonist efficacies were significantly and variably augmented in RSK2 KO MEFs compared with WT MEFs. As a result, relative agonist efficacies were significantly altered, and even reversed, between WT and RSK2 KO MEFs for a single effector readout. This study provides the first evidence that deletion of a single kinase can elicit profound changes in patterns of agonist functional selectivity.

Comparative Efficacy of Inactivated and Live Attenuated Influenza Vaccines

The efficacy of influenza vaccines may vary from year to year, depending on a variety of factors, and may differ for inactivated and live attenuated vaccines. We carried out a randomized, double-blind, placebo-controlled trial of licensed inactivated and live attenuated influenza vaccines in healthy adults during the 2007-2008 influenza season and estimated the absolute and relative efficacies of the two vaccines. A total of 1952 subjects were enrolled and received study vaccines in the fall of 2007. Influenza activity occurred from January through April 2008, with the circulation of influenza types A (H3N2) (about 90%) and B (about 9%). Absolute efficacy against both types of influenza, as measured by isolating the virus in culture, identifying it on real-time polymerase-chain-reaction assay, or both, was 68% (95% confidence interval [CI], 46 to 81) for the inactivated vaccine and 36% (95% CI, 0 to 59) for the live attenuated vaccine. In terms of relative efficacy, there was a 50% (95% CI, 20 to 69) reduction in laboratory-confirmed influenza among subjects who received inactivated vaccine as compared with those given live attenuated vaccine. The absolute efficacy against the influenza A virus was 72% (95% CI, 49 to 84) for the inactivated vaccine and 29% (95% CI, -14 to 55) for the live attenuated vaccine, with a relative efficacy of 60% (95% CI, 33 to 77) for the inactivated vaccine. In the 2007-2008 season, the inactivated vaccine was efficacious in preventing laboratory-confirmed symptomatic influenza A (predominately H3N2) in healthy adults. The live attenuated vaccine also prevented influenza illnesses but was less efficacious. (ClinicalTrials.gov number, NCT00538512.)

Other Paradigms: Growth Rate Constants and Tumor Burden Determined Using Computed Tomography Data Correlate Strongly With the Overall Survival of Patients With Renal Cell Carcinoma

In solid tumors, where curative therapies still elude oncologists, novel paradigms are needed to assess the efficacy of new therapies and those already approved. We used radiologic measurements obtained in patients with metastatic renal cell carcinoma enrolled in a phase II study of the epothilone B analog, ixabepilone (Ixempra), to address this issue. Using a novel 2-phase mathematical equation, we used the radiologic measurements to estimate the concomitant rates of tumor regression and growth (regression and growth rate constants). Eighty-one patients were enrolled on the ixabepilone trial at the time of this analysis. Growth rate constants were determined using computed tomography measurements obtained exclusively while a patient was enrolled on study. The growth rate constants of renal cell carcinomas treated with ixabepilone were significantly reduced compared with those of tumors in patients who received placebo in a previous trial. Furthermore, a correlation with overall survival was found for both the growth rate constant and the initial tumor burden; and this correlation was even stronger when both the growth rate constant and the initial tumor burden were combined. The readily amenable mathematical model described herein has potential applications to many tumor types that can be assessed with imaging modalities. Because the growth rate constant seems to be a surrogate for survival, assessment could aid in the evaluation of relative efficacies of different therapies and perhaps in assessing the potential individual benefit of an experimental therapy.

A Matter of Animation

Education Students of chemistry often have trouble making the connection between macroscopic phenomena they can see and the underlying molecular events operating on a scale too small to visualize directly. Chang et al. investigated whether seventh-grade students' understanding of the molecular structure of matter could improve with the help of computer animation software to portray molecular events in familiar processes such as boiling. Specifically, the authors sought to assess the relative efficacies of three approaches: design and interpretation by individual students of animations illustrating chemical phenomena; self-design of animations followed by interactive critiquing sessions with peers in the class; and examination by students of purely teacher-generated animations. Assessments were based on comparative test performance before and after the animation project. Data from 178 students supported significantly greater gains in understanding among students who participated in peer evaluation than among those who simply prepared animations alone. Thus, including an interactive evaluation component may take more time, but it appears to be time well spent. There was no significant difference in test outcome between the students in the peer-evaluation group and those in the teacher-generated animation group, though the former students did perform slightly better in an assessment of their ability to interpret molecular animations in class. Sci. Educ. 93 , 10.1002/sce.20352 (2009).

Elastic scattering of $\sf{59.54}$ -keV $\sf{\gamma}$ -rays in elements with $\sf{22 \leq {Z} \leq {92}}$ at momentum transfer $\sf{0.4 \leq {x} \leq 4.7~{\AA}^{\sf -1}}$

Differential cross sections for elastic scattering of the 59.54 keV γ-rays in elements with 22 ≤Z ≤92 have been measured over the angular range 10○–160○corresponding to the momentum transfer 0.4 ≤x ≤4.7 A-1. The measurements at forward and backward angles were performed using the 241Am radioactive point-source, target and the Ge detectors in the transmission and reflection arrangements, respectively. The measured differential scattering cross sections are compared with those based on the form-factor (FF) formalism and state-of-the-art S-matrix calculations to differentiate between their relative efficacies and to check angular-dependence of the anomalous scattering factors (ASF) incorporated as correction to the modified form-factor (MF). The S-matrix values exhibit agreement with the measured data at backward angles and differences ∼10% at forward angles. The scattering cross sections based on the MF including ASF’s are in general lower at various angles by up to 20% for medium- and high-Z elements. The observed deviations being higher at the forward angles infer possibility of angular-dependence of ASF’s.