Effect of Problem-based Learning on Motivation in an Urban Science Classroom

This study was conducted in effort to increase class participation and excitement about science in an urban science classroom. It focused on a class of ninth-grade students enrolled in a secondary general science class. The subjects were given a problem-based learning (PBL) project that required them to research an endangered species found in North America. Observations regarding engagement and behavior were recorded daily in a journal. The results show that excitement and participation increased for most, but not all students. However, no decrease in engagement was seen. Classroom behavior also improved during the course of the study. The PBL method proved to he a useful tool for use with this particular class

Editorial

We welcome you to our special issue of Studies in Second Language Learning and Teaching (SSLLT). Our focus is language learning strategies, or LLS. We have been discussing the need for this special issue for years. Over coffee, sodas, or Chardonnet at many conferences and via emails and Skype, we discussed urgent issues in LLS assessment, research, and instruction.SSLLT, like many journals, has published numerous articles involving LLS, and other journals have had special issues on LLS. However, the time is ripe for a special issue that systematically includes LLS for all language skill areas, all major cross-cutting language subsystems such as grammar, and some important yet often ignored topics, such as strategies for learning culture and for technology-enhanced language learning (TELL), which greatly advances decades of research on computer-assisted language learning (CALL). We have gathered articles from a talented team of researchers, most of them well-known and the others rising stars. The articles in this special issue directly involve LLS research in several world regions and allude to such research in many more regions

DISTRIBUTION OF A CROSS-REACTIVE IDIOTYPIC SPECIFICITY IN INBRED STRAINS OF MICE

The expression of an idiotype characteristic of anti-p-azophenylarsonate antibodies of all A/J mice was explored in F1 progeny, in other inbred strains, and in congenic mice. Of the strains tested only those closely related to A/J produced antibodies with the cross-reactive idiotype (CRI). None of the mice synthesized intermediate levels of CRI. No relationship between H-2 type and idiotype was noted. Congenic mice with a strain A background but a different H-2 type produced CRI in amounts quantitatively equivalent to those of strain A mice. Conversely, the presence of the H-2 genotype of strain A on an unrelated background was not associated with the formation of CRI. Nearly all F1 progeny of strain A mice formed CRI, indicating that failure of the other (non-A) parental strain to produce CRI is not attributable to the presence of a gene controlling the synthesis of a suppressor of CRI. NZB mice, which have the same heavy chain allotype as strain A, but are unrelated in origin, failed to produce CRI, although allotype has been shown to be linked to idiotype in congenic strains

REQUIREMENTS FOR PROLONGED SUPPRESSION OF AN IDIOTYPIC SPECIFICITY IN ADULT MICE

The appearance of an idiotypic specificity, present in anti-p-azophenylarsonate (anti-Ar) antibodies of all immunized A/J mice, ran be suppressed in adult mice by prior administration of an IgG fraction of rabbit antiidiotypic (anti-D) antiserum; anti-Ar antibodies arise but are of different idiotype. Prolonged suppression was observed in earlier experiments, but antigen was first administered to adult mice only 2 wk or 9 wk after anti-D antibodies; subsequent escape from idiotypic suppression could have been masked by the capture of antigen by large numbers of memory cells having receptors of a different idiotype. In the present experiments antigen was first administered at intervals up to 22 wk after the antiidiotypic antibody. Suppression was maintained for 6 wk in all mice and for 5 mo in about half the mice tested. It thus appears that suppression of idiotype is less reversible if antigen is administered soon after the antiidiotypic antibody. The data suggest that escape from suppression is attributable to the generation of new precursor cells rather than to reactivation of suppressed cells. The minimum dosage of antiidiotypic IgG required for effective suppression was about 2 mg. The subcutaneous or intraperitoneal routes of inoculation of antiidiotypic IgG were equally effective. When antiidiotypic antibody was administered 3 days after antigen no suppressive effects were observed. There was partial suppression when antiidiotypic antibody was injected on the same day as the antigen. Fab' and F(ab')2 fragments of antiidiotypic IgG had no suppressive effect. Quantitative measurements revealed no significant differences among control and suppressed mice with respect to total concentration of precipitable anti-Ar antibodies produced

Pure hydrogen low-temperature plasma exposure of HOPG and graphene: Graphane formation?

Single- and multilayer graphene and highly ordered pyrolytic graphite (HOPG) were exposed to a pure hydrogen low-temperature plasma (LTP). Characterizations include various experimental techniques such as photoelectron spectroscopy, Raman spectroscopy and scanning probe microscopy. Our photoemission measurement shows that hydrogen LTP exposed HOPG has a diamond-like valence-band structure, which suggests double-sided hydrogenation. With the scanning tunneling microscopy technique, various atomic-scale charge-density patterns were observed, which may be associated with different C-H conformers. Hydrogen-LTP-exposed graphene on SiO₂ has a Raman spectrum in which the D peak to G peak ratio is over 4, associated with hydrogenation on both sides. A very low defect density was observed in the scanning probe microscopy measurements, which enables a reverse transformation to graphene. Hydrogen-LTP-exposed HOPG possesses a high thermal stability, and therefore, this transformation requires annealing at over 1000 °C

Associations between the age at surgical repair in patients with abdominal aortic aneurysms and aortoiliac occlusive disease and smoking and dyslipidemia with reference to PON1–108C>T genotype

Wstęp. Patogeneza tętniaków aorty brzusznej (AAA) i miażdżycy aortalno-biodrowej (AIOD) jest uwarunkowana wieloma czynnikami. Czynniki genetyczne i środowiskowe wpływają zarówno na inicjację, jak i progresję zmian w aorcie. W niniejszym badaniu oceniono asocjacje między wiekiem operacyjnym chorych z AAA i AIOD a występowaniem i nasileniem uznanych czynników ryzyka chorób naczyń oraz genotypem PON1–108C>T. Materiał i metody. Badanie przeprowadzono w grupach 330 chorych z AAA oraz 250 chorych z AIOD. Polimorfizm PON1–108C>T oznaczono za pomocą metody PCR-RFLP. Wyniki. Częstość występowania allela PON1–108T w grupach AAA (0,462) i AIOD (0,479) okazała się zbliżona. W obu grupach chorych młodszy wiek operowanych wiązał się istotnie z paleniem tytoniu, wysokimi stężeniami cholesterolu całkowitego (TC), frakcji LDL i triglicerydów oraz wartościami stosunku cholesterolu całkowitego i frakcji HDL. W przypadku AAA występował również ujemny związek z wartościami wskaźnika masy ciała. Wysoki odsetek cholesterolu frakcji HDL wykazywał ochronny efekt w odniesieniu do progresji AAA/AIOD. W AIOD występował również dodatni związek z wartościami stosunku stężenia cholesterolu frakcji HDL i LDL i występowaniem cukrzycy. Asocjacje między cholesterolem frakcji HDL a wiekiem chorych na AIOD okazały się silniejsze u nosicieli allela –108T. Wykazano niezależne powiązanie pomiędzy wiekiem operacyjnym w przypadku AAA a obecnością nałogu palenia tytoniu oraz wartością triglicerydów u operowanego. Stwierdzono też istnienie zależności pomiędzy wiekiem operacyjnym w przypadku AIOD a wartościami TC, obecnością nałogu palenia tytoniu oraz występowaniem cukrzycy u chorego. Powyższe oddziaływania występowały w większym nasileniu u osób będących homozygotami –108CC. Wnioski. Palenie tytoniu i zaburzenia gospodarki lipidowej są czynnikami o przeważającym wpływie na szybszą progresję AAA i AIOD. U osób, u których te czynniki nie występują, w szczególności w przypadku AIOD, genetycznie uwarunkowane obniżone stężenie paraoksonazy 1 może wpływać na przyspieszoną progresję zmian w aorcie.Background. The pathogenesis of abdominal aortic aneurysms (AAA) and aorto-iliac occlusive disease (AIOD) is multifactorial, and both genetic and environmental factors are involved in the initiation and progression of pathological changes in the aorta. This study is concerned with associations between the age of AAA and AIOD surgical repair and the classical vascular risk factors as well as the paraoxonase 1 (PON1)–108C>T genotypes. Material and methods. The study was conducted on 2 groups: the first group comprised 330 subjects with AAA, and the second group 250 subjects with AIOD. PON1–108C>T polymorphism was ascertained by the PCR-RFLP method. Results. The frequencies of –108T allele, which determine lower paraoxonase level, were similar in the groups of AAA (0.462) and AIOD (0.479) patients. The lower surgical repair age in patients in both groups was significantly associated with smoking and the higher levels of total cholesterol (TC), low density lipoprotein cholesterol (LDLC), and triglicerides (TG) and values of TC/HDLC. In the AAA group the same negative relation was noted with BMI index. The higher values of %HDLC display the protective effect on AAA/AIOD progression. In the AIOD group positive relations were also seen with HDLC/LDLC index and diabetes. Associations between high density lipoprotein cholesterol (HDLC) fraction and age of AIOD repair were stronger in –108T allele carriers. Age of AAA surgical repair was independently related to smoking and TG level, and age of AIOD surgical repair was independently related to smoking, diabetes and TC level. These effects were stronger in PON1–108CC homozygotes. Conclusions. Smoking and impaired lipid profile are prevailing factors determining the rate of AAA and AIOD progression. In the absence of these risk factors, the genetically determined low paraoxonase level may induce the progression of alterations in the aorta, particularly in the case of AIOD

Studies on the separation of 99mTc from large excess of molybdenum

BACKGROUND: Due to aging and unexpected prolonged shutdown of nuclear reactors producing 99Mo for 99Mo/ 99mTc generators it was necessary to explore the alternative methods of technetium-99m production. The first choice were the accelerators. Three years ago IAEA (International Atomic Energy Agency) initiated the Coordinated Research Project “Accelerator-based Alternatives to Non-HEU production of Mo-99 /Tc-99m” aimed at direct production of 99mTc in proton accelerators using the 100Mo(p,2n)99mTc reaction. POLATOM is participating in this enterprise together with the Heavy Ion Laboratory of Warsaw University and the Institute of Nuclear Chemistry and Technology. MATERIAL AND METHODS: 99Mo/99mTc solutions and pure 99mTc used for generators production or milked from ready to use generators were used in experiments. Commercial chromatographic and laboratory-prepared columns were used for separation. The peristaltic pumps were used for solutions delivery onto the columns. Radioactivity of eluted 99Mo and 99mTc was measured using high resolution gamma spectrometry or ionisation chamber in case of high radioactivity. For separation, three different chromatographic methods were used, one based on ion exchange and two on extraction. RESULTS: Synthetic mixtures simulating the real solutions were used. 99mTc is quantitatively bound in the Dowex-1 × 8 column whereas molybdenum is only slightly retained and totally rinsed with 2M NaOH. 99mTc is eluted with TBAB. The elution yield has been reproducible and amounted to 78%. The AnaLig Tc-02 resin column was used for 99mTc retention. Residual Mo was removed by rinsing with 2M NaOH and 99mTc eluted using small volume of water. The recovery was equal to about 85%. Using C-18 column coated with PEG over 80% of 99mTc was recovered in about 50 mL of water. The reduction of volume was necessary. CONCLUSIONS: The recovery of 99mTc was the highest using AnaLig Tc-02 resin. Time of 99mTc separation is the shortest for AnaLig Tc-02 resin and it is not higher than 100 minutes and it can further be shortened

EVIDENCE FOR THE LINKAGE OF THE IGCH LOCUS TO A GENE CONTROLLING THE IDIOTYPIC SPECIFICITY OF ANTI-p-AZOPHENYLARSONATE ANTIBODIES IN STRAIN A MICE

Anti-p-azophenylarsonate (anti-Ar) antibodies elicited in all strain A/J mice tested share one or more idiotypic specificities. These specificities are also found in the anti-Ar antibodies of mice of the closely related strain, AL/N, but not in those of BALB/c mice. Anti-Ar antibodies were elicited in congenic mice in which the IgCH locus of AL/N mice, which controls allotypic markers in the constant regions of heavy chains, had been introgressively backcrossed for nine generations onto a BALB/c background; the mice were then rendered homozygous for the AL/N allotypic determinant. On the average, these antibodies were quantitatively equivalent, with respect to content of the cross-reactive idiotype, to those of AL/N mice. This indicates that the gene controlling the idiotype is closely linked to the IgCH locus. Since idiotype must be a function of V region sequences, the results suggest close linkage of VH and CH genes. The cross-reactive idiotype was found in nearly all F1 mice (C57/BL x A/J or BALB/c x A/J) tested

Sequential Data-Adaptive Bandwidth Selection by Cross-Validation for Nonparametric Prediction

We consider the problem of bandwidth selection by cross-validation from a sequential point of view in a nonparametric regression model. Having in mind that in applications one often aims at estimation, prediction and change detection simultaneously, we investigate that approach for sequential kernel smoothers in order to base these tasks on a single statistic. We provide uniform weak laws of large numbers and weak consistency results for the cross-validated bandwidth. Extensions to weakly dependent error terms are discussed as well. The errors may be {\alpha}-mixing or L2-near epoch dependent, which guarantees that the uniform convergence of the cross validation sum and the consistency of the cross-validated bandwidth hold true for a large class of time series. The method is illustrated by analyzing photovoltaic data.Comment: 26 page

Geometrical Magnetic Frustration in Rare Earth Chalcogenide Spinels

We have characterized the magnetic and structural properties of the CdLn2Se4 (Ln = Dy, Ho), and CdLn2S4 (Ln = Ho, Er, Tm, Yb) spinels. We observe all compounds to be normal spinels, possessing a geometrically frustrated sublattice of lanthanide atoms with no observable structural disorder. Fits to the high temperature magnetic susceptibilities indicate these materials to have effective antiferromagnetic interactions, with Curie-Weiss temperatures theta ~ -10 K, except CdYb2S4 for which theta ~ -40 K. The absence of magnetic long range order or glassiness above T = 1.8 K strongly suggests that these materials are a new venue in which to study the effects of strong geometrical frustration, potentially as rich in new physical phenomena as that of the pyrochlore oxides.Comment: 17 pages, 5 figures, submitted to Phys Rev B; added acknowledgement