Information retention from PowerPoint and traditional lectures

The benefit of PowerPoint^™ is continuously debated, but both supporters and detractors have insufficient empirical evidence. Its use in university lectures has influenced investigations of PowerPoint’s effects on student performance (e.g., overall quiz/exam scores) in comparison to lectures based on overhead projectors, traditional lectures (e.g., “chalk-and-talk”), and online lectures. Thus far, comparisons of overall exam scores have yielded mixed results. The present study decomposes overall quiz scores into auditory, graphic, and alphanumeric scores to reveal new insights into effects of PowerPoint presentations on student performance. Analyses considered retention of lecture information presented to students without the presence of PowerPoint (i.e., traditional lecture), auditory information in the presence of PowerPoint, and visual (i.e., graphic and alphanumeric) information displayed on PowerPoint slides. Data were collected from 62 students via quiz and questionnaire. Students retained 15% less information delivered verbally by the lecturer during PowerPoint presentations, but they preferred PowerPoint presentations over traditional presentations.     

Growth factors in subglottic stenosis

We sought to define the role of fibrogenic peptides in subglottic stenosis (SGS). Biopsy specimens were obtained from patients with stenosis following endotracheal intubation (group 1, n = 5, mean age 5), patients without a history of any precedent trauma, ie. idiopathic stenosis (group 2, n = 3, mean age 40), and those without stenosis (group 3, n = 3, mean age 70). Formalin-fixed biopsy specimens were analyzed following immunohistochemical staining to determine if epidermal growth factor (EGF), platelet-derived growth factor-AA and -BB (PDGF-AA/BB), transforming growth factor-beta 1 and -beta 2 (TGF-beta 1, beta 2), or basic fibroblast growth factor (bFGF) was deposited in these tissues. Blinded analysis revealed TGF-beta 2 and PDGF-AA to be present in seven of eight biopsy specimens from SGS and absent in controls. Staining for PDGF-BB was observed in the mucosa and submucosa and occasionally within vessel walls. Staining of individual growth factors appeared to correlate closely with the presence of granulation tissue. Essentially no bFGF or TGF-beta 1 was observed. Differences were found between patients in groups 1 and 2; tissue from group 1 revealed deposition of EGF and PDGF-BB in submucosa, epithelium, and vasculature. In summary, our experimental findings implicate PDGF and TGF-beta 2, perhaps acting in concert, in mediating the pathologic fibrotic process observed in subglottic stenosis. Epidermal growth factor, in conjunction with TGF-beta and PDGF, may also have a role, but further investigation is needed to more precisely define it.     

ETHANOL FROM SOUTHERN HARDWOODS: THE ROLE OF PRESULFONATION IN THE ACID HYDROLYSIS PROCESS

A two-stage acid hydrolysis process is currently used in the production of ethanol from hardwoods. In this process, dilute sulfuric acid in water at high pressure and short residence times hydrolyzes the wood and first stage substrate. The chemical action is particularly impeded in the second stage by the presence of acid condensed lignin.

Presulfonation followed by delignification is proposed using a sulfur dioxide/water sulfuric acid/ethanol treatment step in place of the first stage acid hydrolysis step to alleviate this problem.

Results presented include the effects caused by varying treatment time, sulfur dioxide concentration, temperature and ethanol concentration on the degree of delignification, and, on the recovery of C₅ and C₆ sugars in the hydrolysates. A preliminary economic feasibility analysis is made to determine the impact of improved ethanol yields and lignin by-product values in the production of ethanol from hardwoods.     

DC harmonic distortion minimization of thyristor converters underunbalanced voltage supply using asymmetrical firing angle

Noncharacteristic harmonics of significant magnitude are produced at the output and input terminals of phase-controlled power converters under unbalanced voltage supply conditions. The concept of switching functions has been proposed before to evaluate the harmonics produced by a phase-controlled six-pulse power converter under both balanced and unbalanced power supply conditions. This paper extends the switching-functions approach to establish analytical equations for the DC output voltage harmonics produced by 12-, 18-, and 24-pulse power converters. The problem is approached from the standpoint of symmetrical voltage components. The increase in distortion under unbalance is caused by the appearance of a second harmonic component. A method, based on an asymmetrical firing angle, to cancel the second harmonic at the power converter output under unbalanced voltage supply is also presented. Cancellation of the second harmonic improves power converter DC output voltage quality     

DEPENDENCE OF MAGNETISM OF Nd-Fe-B SINTERMAGNETS ON ORIENTATION MAGNETIC FIELD

The effect of the orientation magnetic field on the permanent magnetism of Nd-Fe-B sintermagnets is investigated. The results show that the variation law of mag-netism with orientation field obviosly changes at the critical orientation field and the in-tensity of the orientation field should be determined by the dimension ratio of the magnet for effectively utilizing its magnetic energv product.     

APPLICATION OF COMPUTER GRAPHICS IN MARTENSITIC TRANSFORMATION

This paper discuss the stereographic method of martensitic transformation(MT) in the viewof computer graphics(CG)and programs are programmed to realize this method.Habitplane resulting from the programs agrees with that of numerical analysis in terms of the lat-tice parameters of austenite and martensite and shear mechanism supposed inFe-22%Ni-0.8%C alloy,so does orientation relationships.     

Synthesis and Preliminary Evaluation of [11C]GNE-1023 as a Potent PET Probe for Imaging Leucine-Rich Repeat Kinase 2 (LRRK2) in Parkinson's Disease

Leucine-rich repeat kinase 2 (LRRK2) is a large protein involved in the pathogenesis of Parkinson's disease (PD). It has been demonstrated that PD is mainly conferred by LRRK2 mutations that bring about increased kinase activity. As a consequence, selective inhibition of LRRK2 may help to recover the normal functions of LRRK2, thereby serving as a promising alternative therapeutic target for PD treatment. The mapping of LRRK2 by positron emission tomography (PET) studies allows a thorough understanding of PD and other LRRK2-related disorders; it also helps to validate and translate novel LRRK2 inhibitors. However, no LRRK2 PET probes have yet been reported in the primary literature. Herein we present a facile synthesis and preliminary evaluation of [¹¹C]GNE-1023 as a novel potent PET probe for LRRK2 imaging in PD. [¹¹C]GNE-1023 was synthesized in good radiochemical yield (10 % non-decay-corrected RCY), excellent radiochemical purity (>99 %), and high molar activity (>37 GBq μmol⁻¹). Excellent in vitro binding specificity of [¹¹C]GNE-1023 toward LRRK2 was demonstrated in cross-species studies, including rat and nonhuman primate brain tissues by autoradiography experiments. Subsequent whole-body biodistribution studies indicated limited brain uptake and urinary and hepatobiliary elimination of this radioligand. This study may pave the way for further development of a new generation of LRRK2 PET probes.     

REVERSE POTENTIAL PHENOMENA IN THE MEMBRANE-ELECTRODE (M-E) PROCESS

Conventional water treatment techniques typically suffer from severe limitations in selective removal and recovery of heavy metals from dilute solutions. For instance, treatment by pH control, chemical reduction, and chemical oxidation result in precipitation of heavy metaJs, which are subsequently landfilled. Ion exchange suffers from lack of selectivity in cation removal from multi-component mixtures, while electrochemical reduction has severe limitations in dilute solutions. In order to address the problem of selective heavy metal removal and recovery, development of the Membrane-Electrode (M-E) process was undertaken. The M-E process is a hybrid of electrochemical reduction and ion-exchange technologies and permits selective ion-exchange from dilute aqueous solutions.

High cation selectivities in the M-E process is due to controlled rate of ion-exchange. It has been discovered that cation exchange rates can be controlled by application of an electrical potential difference (pd), and that an inverse relationship exists between pd and the rate of ion-exchange. This behavior is termed as the “Reverse-Potential Phenomena”. Typically, the rate of ion-exchange in conventional ion-exchange processes is dependent upon the cation concentration in solution, and cation loading on the ion-exchange material; this rate cannot be controlled by external means.

Thus far, the M-E process has been effectively demonstrated for selective recovery of Pb²⁺ and Cu²⁺ ions from dilute aqueous binary and ternary cation solutions [,]. This paper focuses on the effect of Reverse-Potential phenomena on selectivity in the Cu²⁺ and Ni²⁺ binary solution mixture.