Imaging Magnetic Focusing of Coherent Electron Waves

The magnetic focusing of electrons has proven its utility in fundamental studies of electron transport. Here we report the direct imaging of magnetic focusing of electron waves, specifically in a two-dimensional electron gas (2DEG). We see the semicircular trajectories of electrons as they bounce along a boundary in the 2DEG, as well as fringes showing the coherent nature of the electron waves. Imaging flow in open systems is made possible by a cooled scanning probe microscope. Remarkable agreement between experiment and theory demonstrates our ability to see these trajectories and to use this system as an interferometer. We image branched electron flow as well as the interference of electron waves. This technique can visualize the motion of electron waves between two points in an open system, providing a straightforward way to study systems that may be useful for quantum information processing and spintronics

Mineralogical evolution of cement pastes at early ages based on thermogravimetric analysis (TGA)

[EN] Ordinary thermogravimetric analysis (TG) and high-resolution TG tests were carried out on three different Portland cement pastes to study the phases present during the first day of hydration. Tests were run at 1, 6, 12 and 24 h of hydration, in order to determine the phases at these ages. High-resolution TG tests were used to separate decompositions presented in the 100¿200 C interval. The non-evaporable water determined by TG was used to determine hydration degree for the different ages. The effect of particle size distribution (PSD) on mineralogical evolution was established, as well as the addition of calcite as mineralogical filler. Finer PSD and calcite addition accelerate the hydration process, increasing the hydration degree on the first day of eaction between water and cement. According to high-resolution TG results, it was demonstrated that ettringite was the only decomposed phase in the 100¿200 C interval during the first 6 h of hydration for all studied cements. C-S-H phase starts to appear in all cements after 12 h of hydration.Funding was provided by Colciencias (Grant No. Convocatoria 567-2012).Gaviria, X.; Borrachero Rosado, MV.; Paya Bernabeu, JJ.; Monzó Balbuena, JM.; Tobón, J. (2018). Mineralogical evolution of cement pastes at early ages based on thermogravimetric analysis (TGA). Journal of Thermal Analysis and Calorimetry. 132(1):39-46. https://doi.org/10.1007/s10973-017-6905-0S39461321Benboudjema F, Meftah JM, Torernti F. Interaction between drying, shrinkage, creep and cracking phenomena in concrete. Eng Struct. 2005;27:239–50.Holt E. Contribution of mixture design to chemical and autogenous shrinkage of concrete at early ages. Cem Concr Res. 2005;35:464–72.Darquennes A, Staquet S, Delplancke-Ogletree MP, Espion B. Effect of autogenous deformation on the cracking risk of slag cement concretes. Cem Concr Compos. 2011;33:368–79.Slowik V, Schmidt M, Fritzsch R. Capillary pressure in fresh cement-based materials and identification of the air entry value. Cem Concr Compos. 2008;30(7):557–65.Evju C, Hansen S. Expansive properties of ettringite in a mixture of calcium aluminate cement, Portland cement and ß-calcium sulfate hemihydrates. Cem Concr Res. 2001;31:257–61.Bentz DP, Jensen OM, Hansen KK. Olesen, Stang, H. Haecker, C.J. Influence of cement particle-size distribution on early age autogenous strain and stresses in cement-based materials. J Am Ceram Soc. 2001;84(1):129–35.Barcelo L, Moranville M, Clavaud B. Autogenous shrinkage of concrete: a balance between autogenous swelling and self-desiccation. Cem Concr Res. 2005;35(1):177–83.Bouasker M, Mounanga P, Turcry P, Loukili A, Khelidj A. Chemical shrinkage of cement pastes and mortars at very early age: effect of limestone filler and granular inclusions. Cem Concr Compos. 2008;30(1):13–22.Bentz DP. A review of early-age properties of cement-based materials. Cem Concr Res. 2008;38(2):196–204.Ozawa T. Controlled rate thermogravimetry. New usefulness of controlled rate thermogravimetry revealed by decomposition of polyimide. J Therm Anal Calorim. 2000;59:375–84.Ramachandran VS, Paroli RM, Beaudoin JJ, Delgado AH. Thermal analysis of construction materials. Building materials series. New York: Noyes Publications; 2003.Zanier A. High-resolution TG for the characterization of diesel fuel additives. J Therm Anal Calorim. 2001;64:377–84.Tobón JI, Payá J, Borrachero MV, Restrepo OJ. Mineralogical evolution of Portland cement blended with silica nanoparticles and its effect on mechanical strength. Constr Build Mater. 2012;36:736–42.Singh M, Waghmare S, Kumar V. Characterization of lime plasters used in 16th century Mughal Monument. J Archeol Sci. 2014;42:430–4.Majchrzak-Kuçeba I. Thermogravimetry applied to characterization of fly ash-based MCM-41 mesoporous materials. J Therm Anal Calorim. 2012;107:911–21.Silva ACM, Gálico DA, Guerra RB, Legendre AO, Rinaldo D, Galhiane MS, Bannach G. Study of some volatile compounds evolved from the thermal decomposition of atenolol. J Therm Anal Calorim. 2014;115:2517–20.Rios-Fachal M, Gracia-Fernández C, López-Beceiro J, Gómez-Barreiro S, Tarrío-Saavedra J, Ponton A, Artiaga R. Effect of nanotubes on the thermal stability of polystyrene. J Therm Anal Calorim. 2013;113:481–7.Yamarte L, Paxman D, Begum S, Sarkar P, Chambers A. TG measurement of reactivity of candidate oxygen carrier materials. J Therm Anal Calorim. 2014;116:1301–7.Borrachero MV, Payá J, Bonilla M, Monzó J. The use of thermogravimetric analysis technique for the characterization of construction materials. The gypsum case. J Therm Anal Calorim. 2008;91(2):503–9.Tobón JI, Payá J, Borrachero MV, Soriano L, Restrepo OJ. Determination of the optimum parameters in the high resolution thermogravimetric analysis (HRTG) for cementitious materials. J Therm Anal Calorim. 2012;107:233–9.Kuzielova E, Žemlička M, Másilko, J, Palou, M.T. Effect of additives on the performance of Dyckerhoff cement, Class G, submitted to simulated hydrothermal curing. J Therm Anal Calorim. Accepted 29 Oct 2017Genc M, Genc ZK. Microencapsulated myristic acid–fly ash with TiO2 shell as a novel phase change material for building application. J Therm Anal Calorim. Accepted 24 Oct 2017.Singh M, Kumar SV, Waghmare SA. The composition and technology of the 3–4th century CE decorative earthen plaster of Pithalkhora caves, India. J Archeol Sci. 2016;7:224–37.Liu L, Liu Q, Cao Y, Pan WP. The isothermal studies of char-CO2 gasification using the high-pressure thermo-gravimetric method. J Therm Anal Calorim. 2015;120:1877–82.Majchrzak-Kuce I, Bukalak-Gaik D. Regeneration performance of metal–organic frameworks TG-vacuum tests. J Therm Anal Calorim. 2016;125:1461–6.Ion RM, Radovici C, Fierascu RC, Fierascu I. Thermal and mineralogical investigations of iron archaeological Materials. J Therm Anal Calorim. 2015;121:1247–53.Rupasinghe M, San Nicolas R, Mendis P, Sofi M, Ngo T. Investigation of strength and hydration characteristics in nano-silica incorporated cement paste. Cem Concr Compos. 2017;80:17–30.Esteves PL. On the hydration of water-entrained cement–silica systems: combined SEM, XRD and thermal analysis in cement pastes. Thermochim Acta. 2011;518:27–35.Riesen R. Adjustment of heating rate for maximum resolution in TG and TMA (MaxRes). J Therm Anal. 1998;53:365–74.Lim S, Mondal P. Micro- and nano-scale characterization to study the thermal degradation of cement-based materials. Mater Charact. 2014;92:15–25.Gill PS, Sauerbrunn SR, Crowe BS. High resolution thermogravimetry. J Therm Anal. 1992;38:255–66.Mounanga P, Khelidj A, Loukili A, Baroghel-Bouny V. Predicting Ca(OH)2 content and chemical shrinkage of hydrating cement pastes using analytical approach. 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Selective phosphodiesterase inhibitors: a promising target for cognition enhancement

# The Author(s) 2008. This article is published with open access at Springerlink.com Rationale One of the major complaints most people face during aging is an impairment in cognitive functioning. This has a negative impact on the quality of daily life and is even more prominent in patients suffering from neurodegenerative and psychiatric disorders including Alzheimer’s disease, schizophrenia, and depression. So far, the majority of cognition enhancers are generally targeting one particular neurotransmitter system. However, recently phosphodiesterases (PDEs) have gained increased attention as a potential new target for cognition enhancement. Inhibition of PDEs increases the intracellular availability of the second messengers cGMP and/or cAMP. Objective The aim of this review was to provide an overvie

Alpha shapes: Determining 3D shape complexity across morphologically diverse structures

Background. Following recent advances in bioimaging, high-resolution 3D models of biological structures are now generated rapidly and at low-cost. To utilise this data to address evolutionary and ecological questions, an array of tools has been developed to conduct 3D shape analysis and quantify topographic complexity. Here we focus particularly on shape techniques applied to irregular-shaped objects lacking clear homologous landmarks, and propose the new ‘alpha-shapes’ method for quantifying 3D shape complexity. Methods. We apply alpha-shapes to quantify shape complexity in the mammalian baculum as an example of a morphologically disparate structure. Micro- computed-tomography (μCT) scans of bacula were conducted. Bacula were binarised and converted into point clouds. Following application of a scaling factor to account for absolute differences in size, a suite of alpha-shapes was fitted to each specimen. An alpha shape is a formed from a subcomplex of the Delaunay triangulation of a given set of points, and ranges in refinement from a very coarse mesh (approximating convex hulls) to a very fine fit. ‘Optimal’ alpha was defined as the degree of refinement necessary in order for alpha-shape volume to equal CT voxel volume, and was taken as a metric of overall shape ‘complexity’. Results Our results show that alpha-shapes can be used to quantify interspecific variation in shape ‘complexity’ within biological structures of disparate geometry. The ‘stepped’ nature of alpha curves is informative with regards to the contribution of specific morphological features to overall shape ‘complexity’. Alpha-shapes agrees with other measures of topographic complexity (dissection index, Dirichlet normal energy) in identifying ursid bacula as having low shape complexity. However, alpha-shapes estimates mustelid bacula as possessing the highest topographic complexity, contrasting with other shape metrics. 3D fractal dimension is found to be an inappropriate metric of complexity when applied to bacula. Conclusions. The alpha-shapes methodology can be used to calculate ‘optimal’ alpha refinement as a proxy for shape ‘complexity’ without identifying landmarks. The implementation of alpha-shapes is straightforward, and is automated to process large datasets quickly. Beyond genital shape, we consider the alpha-shapes technique to hold considerable promise for new applications across evolutionary, ecological and palaeoecological disciplines

Pharmacological and behavioral determinants of cocaine, methamphetamine, 3,4-methylenedioxymethamphetamine, and para -methoxyamphetamine-induced hyperthermia

The original publication is available at www.springerlink.comRationale: Cocaine, methamphetamine, 3,4-methylenedioxymethamphetamine (MDMA, ecstasy), and para-methoxyamphetamine (PMA) disrupt normal thermoregulation in humans, with PMA being associated with more severe cases of hyperthermia. Harm minimization advice on how to prevent overheating depends on appropriate thermoregulatory behavior by drug users. Objectives: The purpose of the current study was to establish dose–response relationships for the effects of a number of commonly used illicit stimulants and investigate the behavioral response to increased core temperature. Materials and methods Sprague-Dawley rats with telemetry implants were administered either saline or 4, 12, 26, 40 or 80 μmol/kg of cocaine, methamphetamine, MDMA, or PMA and confined to an ambient temperature of 30°C for 30 min, before being able to choose their preferred temperature on a thermally graded runway (11-41°C). Results: The increased core temperature caused by administration of cocaine, methamphetamine, and MDMA treatment led to the animals seeking the cool end of the runway to correct their core temperature, although this did not occur in PMA-treated rats. The order of potency for increasing core temperature was methamphetamine >PMA = MDMA> cocaine. This differed to the slopes of the dose–response curves where MDMA and PMA showed the steepest slope for the doses used followed by methamphetamine then cocaine. Conclusions: These results suggest that behavioral aspects of thermoregulation are important in assessing the potential of individual drugs to cause harmful increases in core temperature.Emily Joy Jaehne, Abdallah Salem and Rodney James Irvin

Dietary patterns and changes in frailty status: the Rotterdam study

Purpose: To determine the associations between a priori and a posteriori derived dietary patterns and a general state of health, measured as the accumulation of deficits in a frailty index. Methods: Cross-sectional and longitudinal analysis embedded in the population-based Rotterdam Study (n = 2632) aged 45 years. Diet was assessed at baseline (year 2006) using food frequency questionnaires. Dietary patterns were defined a priori using an existing index reflecting adherence to national dietary guidelines and a posteriori using principal component analysis. A frailty index was composed of 38 health deficits and measured at baseline and follow-up (4 years later). Linear regression analyses were performed using adherence to each of the dietary patterns as exposure and the frailty index as outcome (all in Z-scores). Results: Adherence to the national dietary guidelines was associated with lower frailty at baseline (β −0.05, 95% CI −0.08, −0.02). Additionally, high adherence was associated with lower frailty scores over time (β −0.08, 95% CI −0.12, −0.04). The PCA revealed three dietary patterns that we named a “Traditional” pattern, high in legumes, eggs and savory snacks; a “Carnivore” pattern, high in meat and poultry; and a “Health Conscious” pattern, high in whole grain products, vegetables and fruit. In the cross-sectional analyses adherence to these patterns was not associated with frailty. However, adherence to the “Traditional” pattern was associated with less frailty over time (β −0.09, 95% CI −0.14, −0.05). Conclusion: No associations were found for adherence to a “healthy” pattern or “Carnivore” pattern. However, Even in a population that is relatively young and healthy, adherence to dietary guidelines or adherence to the Traditional pattern could help to prevent, delay or reverse frailty levels