Adaptive Guidance: Effects On Self-Regulated Learning In Technology-Based Training

Guidance provides trainees with the information necessary to make effective use of the learner control inherent in technology-based training, but also allows them to retain a sense of control over their learning (Bell & Kozlowski, 2002). One challenge, however, is determining how much learner control, or autonomy, to build into the guidance strategy. We examined the effects of alternative forms of guidance (autonomy supportive vs. controlling) on trainees’ learning and performance, and examined trainees’ cognitive ability and motivation to learn as potential moderators of these effects. Consistent with our hypotheses, trainees receiving adaptive guidance had higher levels of knowledge and performance than trainees in a learner control guidance. Controlling guidance had the most consistent positive impact on the learning outcomes, while autonomy supportive guidance demonstrated utility for more strategic outcomes. In addition, guidance was generally more effective for trainees with higher levels of cognitive ability and autonomy guidance served to enhance the positive effects of motivation to learn on the training outcomes

The N\'eel order for a frustrated antiferromagnetic Heisenberg model: beyond linear spin-wave theory

Within Dyson-Maleev (DM) transformation and self-consistent mean-field treatment, the N\'eel order/disorder transition is studied for an antiferromagnetic Heisenberg model which is defined on a square lattice with a nearest neighbour exchange $J_1$ and a next-nearest neighbour exchange $J_2$ along only one of the diagonals. It is found that the N\'eel order may exist up to $J_2/J_1=0.572$, beyond its classically stable regime. This result qualitatively improves that from linear spin-wave theory based on Holstein-Primakoff transformation.Comment: 10 pages, 4 eps figure

Magnetism and superconductivity of strongly correlated electrons on the triangular lattice

We investigate the phase diagram of the \tj Model on a triangular lattice using a Variational Monte-Carlo approach. We use an extended set of Gutzwiller projected fermionic trial wave-functions allowing for simultaneous magnetic and superconducting order parameters. We obtain energies at zero doping for the spin-1/2 Heisenberg model in very good agreement with the best estimates. Upon electron doping (with a hopping integral $t<0$) this phase is surprisingly stable variationally up to $n\approx 1.4$, while the $d_{x^{2}-y^{2}}+i d_{xy}$ order parameter is rather weak and disappears at $n\approx 1.1$. For hole doping however the coplanar magnetic state is almost immediately destroyed and $d_{x^{2}-y^{2}}+i d_{xy}$ superconductivity survives down to $n\approx 0.8$. For lower $n$, between 0.2 and 0.8, we find saturated ferromagnetism. Moreover, there is evidence for a narrow spin density wave phase around $n\approx 0.8$. Commensurate flux phases were also considered, but these turned out {\em not} to be competitive at finite doping.Comment: 11 pages; 11 figure

Direct Calculation of the Spin Stiffness in the J1J_1--J2J_2 Heisenberg Antiferromagnet

We calculate the spin stiffness $\rho_s$ for the frustrated spin-$\frac{1}{2}$ Heisenberg antiferromagnet on a square lattice by exact diagonalizations on finite clusters of up to $36$ sites followed by extrapolations to the thermodynamic limit. For the non-frustrated case, we find that $\rho_s = (0.183\pm 0.003)J_1$, in excellent agreement with the best results obtained by other means. Turning on frustration, the extrapolated stiffness vanishes for $0.4 \lesssim J_2/J_1 \lesssim 0.6$. In this intermediate region, the finite-size scaling works poorly -- an additional sign that their is neither N\'eel nor collinear magnetic order. Using a hydrodynamic relation, and previous results for the transverse susceptibility, we also estimate the spin-wave velocity in the N\'eel-ordered region.Comment: 4 pages, uuencoded compressed ps-file (made with uufiles

Freezing and large time scales induced by geometrical frustration

We investigate the properties of an effective Hamiltonian with competing interactions involving spin and chirality variables, relevant for the description of the {\it trimerized} version of the spin-1/2 {\it kagome} antiferromagnet. Using classical Monte Carlo simulations, we show that remarkable behaviors develop at very low temperatures. Through an {\it order by disorder} mechanism, the low-energy states are characterized by a dynamical freezing of the chiralities, which decouples the lattice into ``dimers'' and ``triangles'' of antiferromagnetically coupled spins. Under the presence of an external magnetic field, the particular topology of the chiralities induces a very slow spin dynamics, reminiscent of what happens in ordinary spin glasses.Comment: 12 pages, 13 figure

Alpha-1-antitrypsin deficiency: Molecular basis, clinical presentation, therapeutic options and an integrative approach in diagnostics

Primarna uloga alfa-1-antitripsina (AAT) jeste da zaštiti plućni parenhim od proteolize dejstvom neutrofilne elastaze. Njegovu biosintezu kontroliše izuzetno polimorfni GEN SERPINA1. Deficijencija AAT (AATD) jeste autozomalno recesivno oboljenje i smatra se najčešćim genetskim uzrokom oboljenja jetre kod dece i emfizema kod odraslih. Prema učestalosti, deficijentni aleli se mogu podeliti na "česte" (Z i S) i "retke" (Mmalton, Mheerlen, Mprocida itd.). Za vrstu, intenzitet i vremenski period u kome se razvijaju kliničke manifestacije smatra se odgovornim interakcija AATD i dodatnih genetskih i stečenih faktora rizika (pušenje, izloženost aerozagađenju i sl.). Kod obolelih se najčešće javljaju preuranjen emfizem, hronični hepatitis, ciroza i hepatocelularni karcinom. Epidemiološke studije naglašavaju potrebu povećanja dijagnostičke efikasnosti kod AATD. Preporučuje se da dijagnostički pristup integriše precizne, međunarodno identifikovane, kliničke kriterijume i standardizovan laboratorijski protokol, zasnovan na biohemijskim i molekularno-biološkim metodama. Terapijski pristup zavisi od vrste kliničkih manifestacija. Kod pulmoloških bolesnika je moguće primeniti terapiju nadoknade, dok kod osoba sa terminalnom fazom oštećenja jetre uzrokovanog AATD transplantacija trenutno predstavlja jedinu specifičnu terapiju. Kod svih obolelih je neophodno preventivno uticati na smanjenje štetnog uticaja životnih navika i faktora sredine. Očekuje se da zdravstveni ishodi kod obolelih budu značajno unapređeni uvođenjem genske terapije. Dosadašnji rezultati istraživanja efikasnosti integrativnog pristupa detekciji AATD u populaciji Srbije su ohrabrujući i upućuju na potrebu njegovog omasovljenja, čime bi se ostvarili uslovi za formiranje nacionalnog registra obolelih.The primary role of Alpha-1-antitrypsin (AAT), encoded by the highly polymorphic SERPINA1 gene, is to protect the lung parenchyma from proteolysis by neutrophil elastase. AAT deficiency (AATD) is an autosomal recessive disease, considered as the most important genetic cause of liver disease in children and emphysema in adults. According to frequency, deficient alleles can be classified as "common" (Z and S) and "rare" (Mmalton, Mheerlen, Mprocida etc). Type, intensity and onset of clinical disease associated with AATD occur as a result of interaction between AATD and additional genetic and acquired factors (tobacco smoking, air pollution exposure etc). The most frequent clinical manifestations include premature emphysema, chronic hepatitis, cirrhosis and hepatocellular carcinoma. Epidemiological studies highlight the need for improvement in diagnostic efficiency for AATD. It is recommended for a diagnostic approach to integrate precise, internationally recognized clinical criteria and a standardized laboratory protocol, based on a combination of biochemical and molecular methods. The predilection site of clinical manifestations guides the therapeutic approach. Augmentation therapy is possible in lung disease, while currently the only specific measure in patients with severe liver failure due to AATD is transplantation. In all patients, preventive measures, ammeliorating the deleterious effects of habits and environmental factors are recommended. Introduction of gene therapy is expected to additionally improve health outcomes in affected persons. Current results with an integrative AATD diagnostic strategy in the Serbian population are highly encouraging, prompting towards its further implementation in common medical practice with the ultimate goal to establish a national register of affected individuals

Is an integrative laboratory algorithm more effective in detecting alpha-1-antitrypsin deficiency in patients with premature chronic obstructive pulmonary disease than AAT concentration based screening approach?

Introduction: Alpha-1-antitrypsin deficiency (AATD), genetic risk factor for premature chronic obstructive pulmonary disease (COPD), often remains undetected. The aim of our study was to analyse the effectiveness of an integrative laboratory algorithm for AATD detection in patients diagnosed with COPD by the age of 45 years, in comparison with the screening approach based on AAT concentration measurement alone. Subjects and methods: 50 unrelated patients (28 males / 22 females, age 52 (24-75 years) diagnosed with COPD before the age of 45 years were enrolled. Immunonephelometric assay for alpha-1-antitrypsin (AAT) and PCR-reverse hybridization for Z and S allele were first-line, and isoelectric focusing and DNA sequencing (ABI Prism BigDye) were reflex tests. Results: AATD associated genotypes were detected in 7 patients (5 ZZ, 1 ZM(malton), 1 ZQ0(amersfoort)), 10 were heterozygous carriers (8 MZ and 2 MS genotypes) and 33 were without AATD (MM genotype). Carriers and patients without AATD had comparable AAT concentrations (P = 0.125). In majority of participants (48) first line tests were sufficient to analyze AATD presence. In two remaining cases reflex tests identified rare alleles, M-malton and Q0(amersfoort), the later one being reported for the first time in Serbian population. Detection rate did not differ between algorithm and screening both for AATD (P = 0.500) and carriers (P = 0.063). Conclusion: There is a high prevalence of AATD affected subjects and carriers in a group of patients with premature COPD. The use of integrative laboratory algorithm does not improve the effectiveness of AATD detection in comparison with the screening based on AAT concentration alone

Quantum Phase Transition in Frustrated Two-Dimensional Antiferromagnets

We study frustrated, two-dimensional, quantum antiferromagnets in the vicinity of a quantum transition from a non-collinear, magnetically-ordered ground state to a quantum disordered phase. The general scaling properties of this transition are described. A detailed study of a particular field-theoretic model of the transition, with bosonic spin-1/2 spinon fields, is presented. Explicit universal scaling forms for a variety of observables are obtained and the results are compared with numerical data on the spin-1/2 triangular antiferromagnet. Universal properties of an alternative field-theory, with confined spinons, are also briefly noted.Comment: 51 pages, REVTEX 3.0, 5 uuencoded EPS figures appended, YCTP-xxz

Superconductivity and Spin Fluctuations in the Electron-Doped Infinitely-Layered High Tc Superconductor Sr0.9_0.9La0.1_0.1CuO2_2 (Tc=42K)

This paper describes the first 63-Cu NMR study of an electron-doped infinitely-layered high Tc superconductor Sr$_0.9$La$_0.1$CuO$_2$ (Tc=42K). The spin dynamics in the normal state above Tc exhibits qualitatively the same behavior as some hole-doped materials with significantly enhanced spin fluctuations. Below Tc, we observed no signature of a Hebel-Slichter coherence peak, suggesting an unconventional nature of the symmetry of the superconducting order parameter.Comment: Invited Paper to SNS-95 Conference (Spectroscopies on Novel Superconductors 1995 at Stanford). Also presented at Aspen Winter Conference on Superconductivity and Grenoble M^2S-HTSC in 199