Whither Does the Sun Rove?

If one asked some friends where on the horizon they should expect to see the sunrise, half of the answers would be "in the east." Of course, something analogous would happen with the sunset and the west. However, sunrise and sunset virtually never occur at these cardinal points. In fact, those answers correctly describe observations only during the equinoxes, when either autumn or spring begin. Once we recall this, the next natural question to ask ourselves is: how far from the east (or from the west) the rising (or setting) Sun is located for a given latitude of the observer and for a given day of the year. In this paper we supply some simple tools to easily visualize the angular (southward or northward) departure of the rising and setting Sun on the horizon from the east-west direction in a pictorial way, without the need of mathematics. These tools have proven a valuable resource in teaching introductory physics and astronomy courses.Fil: Gangui, Alejandro. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; Argentin

The role of water in the primary nucleation of protein amyloid aggregation

The understanding of the complex conformational landscape of amyloid aggregation and its modulation by relevant physicochemical and cellular factors is a prerequisite for elucidating some of the molecular basis of pathology in amyloid related diseases, and for developing and evaluating effective disease-specific therapeutics to reduce or eliminate the underlying sources of toxicity in these diseases. Interactions of proteins with solvating water have been long considered to be fundamental in mediating their function and folding; however, the relevance of water in the process of protein amyloid aggregation has been largely overlooked. Here, we provide a perspective on the role water plays in triggering primary amyloid nucleation of intrinsically disordered proteins (IDPs) based on recent experimental evidences. The initiation of amyloid aggregation likely results from the synergistic effect between both protein intermolecular interactions and the properties of the water hydration layer of the protein surface. While the self-assembly of both hydrophobic and hydrophilic IDPs would be thermodynamically favoured due to large water entropy contributions, large desolvation energy barriers are expected, particularly for the nucleation of hydrophilic IDPs. Under highly hydrating conditions, primary nucleation is slow, being facilitated by the presence of nucleation-active surfaces (heterogeneous nucleation). Under conditions of poor water activity, such as those found in the interior of protein droplets generated by liquid-liquid phase separation, however, the desolvation energy barrier is significantly reduced, and nucleation can occur very rapidly in the bulk of the solution (homogeneous nucleation), giving rise to structurally distinct amyloid polymorphs. Water, therefore, plays a key role in modulating the transition free energy of amyloid nucleation, thus governing the initiation of the process, and dictating the type of preferred primary nucleation and the type of amyloid polymorph generated, which could vary depending on the particular microenvironment that the protein molecules encounter in the cell

How does carer management style influence the performance of activities of daily living in people with dementia?

INTRODUCTION: People with Dementia (PwD)’s performance of activities of daily living (ADLs) has been associated with apathy, cognitive deficits, carers’ depression and burden. However, it is not known if the carers’ management style affects ADL performance, particularly alongside PwD’s cognitive deficits and apathy. Thus, the aim of this study was to explore the contribution of intrinsic (cognition, apathy) and extrinsic (carer management styles) dementia factors to ADL performance. METHODS: PwD (n=143) were assessed on global cognition (ACE-III); apathy (CBI-R); ADLs (Disability Assessment for Dementia-DAD). Carers’ (n=143) criticism, encouragement and active-management styles were assessed with the Dementia Management Strategy Scale (DMSS). Multiple linear regression analysis investigated contributions of carer styles, cognition, apathy (independent variables) on ADLs (dependent variable). RESULTS: The best model explaining the variance of the DAD scores included cognition (β =0.413, t(142)=4.463, p=0.001), apathy (β =-0.365, t(142)=-5.556, p=0.001), carer criticism (β =-0.326, t(142)=-2.479, p=0.014) and carer encouragement styles (β =0.402, t(142)=2.941, p=0.004) accounting for 40% of the variance of the DAD scores. CONCLUSIONS: This novel study demonstrated that PwD’s level of apathy and the carer’s use of criticism negatively affected ADL performance while PwD’s cognitive abilities and carer encouragement style improved ADL performance. These findings have critical implications for the development of novel multi-component non-pharmacological interventions to maintain function and delay disease progression in dementia, as well as direct relevance to current carers and families

Measurement of filling factor 5/2 quasiparticle interference: observation of charge e/4 and e/2 period oscillations

A standing problem in low dimensional electron systems is the nature of the 5/2 fractional quantum Hall state: its elementary excitations are a focus for both elucidating the state's properties and as candidates in methods to perform topological quantum computation. Interferometric devices may be employed to manipulate and measure quantum Hall edge excitations. Here we use a small area edge state interferometer designed to observe quasiparticle interference effects. Oscillations consistent in detail with the Aharanov-Bohm effect are observed for integer and fractional quantum Hall states (filling factors 2, 5/3, and 7/3) with periods corresponding to their respective charges and magnetic field positions. With these as charge calibrations, at 5/2 filling factor and at lowest temperatures periodic transmission through the device consistent with quasiparticle charge e/4 is observed. The principal finding of this work is that in addtion to these e/4 oscillations, periodic structures corresponding to e/2 are also observed at 5/2 and at lowest temperatures. Properties of the e/4 and e/2 oscillations are examined with the device sensitivity sufficient to observe temperature evolution of the 5/2 quasiparticle interference. In the model of quasiparticle interference, this presence of an effective e/2 period may empirically reflect an e/2 quasiparticle charge, or may reflect multiple passes of the e/4 quasiparticle around the interferometer. These results are discussed within a picture of e/4 quasiparticle excitations potentially possessing non-Abelian statistics. These studies demonstrate the capacity to perform interferometry on 5/2 excitations and reveal properties important for understanding this state and its excitations.Comment: version 3 contains additional data beyond version 2, 26 pages, 8 figures PNAS 081259910

A New and Tidier Setting How Does Environmental Clutter Affect People With Dementia’s Ability to Perform Activities of Daily Living?

Background: The relationship between the physical environment and the person with dementia’s (PwD) activities of daily living (ADLs) task performance is controversial. Although the general assumption is that this population benefits from their home environment when performing ADLs, very few experimental studies have been conducted to date. Objectives: The aim was to investigate the influence of the environment (home vs. Research-lab) and the role of clutter on ADL performance. Methods: Sixty-five PwD were evaluated with a performance-based ADL assessment (at home and clutter-free Research-lab). Paired t tests compared ADL performance and level of clutter in both environments. Multiple regression analysis investigated factors associated with better ADL performance. Results: Overall, PwD performed better at home even though clutter was significantly lower in the Research-lab. When stratified by dementia stage, PwD in the moderate stage of the disease performed better at home. Conclusion: Absence of clutter in the Research-Lab did not appear to play a beneficial role in ADLs. When stratified by dementia stage, only PwD in the moderate stage appeared to benefit from their home environment when performing ADL tasks. Future studies are required to elucidate the wider role of the environment in supporting engagement in daily activities in different dementia stages

Contributions of Caregiver Management Styles to the Discrepancy Between Reported and Observed Task Performance in People with Dementia

Background: The identification and understanding of the discrepancy between caregivers’ reports of people with dementia’s (PwD) performance of activities of daily living (ADLs) and observed performance, could clarify what kind of support a PwD effectively needs when completing tasks. Strategies used by caregivers have not been included in the investigation of this discrepancy. Objectives: To (1) investigate if caregivers’ report of PwD’s ADL performance are consistent with PwD’s observed performance; (2) explore if caregiver management styles, depression, and anxiety, contribute to this discrepancy. Methods: PwD (n=64) were assessed with standardised performance-based (AMPS) and informant-based (DAD) ADL assessments. Caregivers completed depression (PHQ-9), anxiety (GAD-7), and dementia management style (DMSS: criticism, active-management, and encouragement) questionnaires. Cohen’s kappa determined agreement/disagreement in ADL performance. To investigate the potential discrepancy between the DAD and AMPS, a continuous variable was generated: comparative ADL score. Multiple linear regression analysis explored whether caregivers’ management styles, depression or anxiety could explain the ADL discrepancy. Results: Poor level of agreement between observed and reported ADL performance [k= -0.025 (95%CI -0.123 – 0.073)] was identified, with most caregivers underestimating ADL performance. The combined model explained 18% (R2=0.18, F(5, 55)=2.52,p=<0.05) of the variance of the comparative ADL score. Active-management (β=-0.037,t(60)=-3.363, p=0.001) and encouragement (β=0.025,t(60)=2.018, p=0.05) styles made the largest and statistically significant contribution to the model. Conclusions: Encouragement style could be advised for caregivers who underestimate ADL performance, while active management style for those who overestimate it. Findings have scope to increase caregivers’ abilities to support PwD activity engagement in daily life

Inverse Control and Stabilization of Free-flying Flexible Robots

The question of control and stabilization of flexible space robots is considered. Although, this approach is applicable to space robots of other configurations, for simplicity, a flexible planar two-link robot, mounted on a rigid floating platform, is considered. The robotic arm has two revolute joints and its links undergo elastic deformation in the plane of rotation. Based on nonlinear inversion technique, a control law is derived for controlling output variables describing the position and orientation of the platform and the joint angles of the robot. Although, the inverse controller accomplishes reference trajectory tracking, it excites the elastic modes of the arm. For the vibration suppression, three different stabilizer are designed. Using linear quadratic optimal control theory, a composite stabilizer for stabilization of the rigid and flexible modes and a decoupled flexible mode stabilizer are designed for regulating the end point of the robot to the target point and vibration suppression. Stabilization using only elastic mode velocity feedback is also considered. For large maneuvers, first the inverse controller is active, and the stabilizer is switched for regulation when the motion of the robot lies in the neighborhood of the terminal equilibrium state. Simulation results are presented to show that in the closed-loop system including the inverse controller and each of the stabilizers, trajectory tracking and stabilization of elastic modes are accomplished

MTOR pathway is involved in energy homeostasis regulation as a part of the gut?brain axis

Mammalian, or mechanic, target of rapamycin (mTOR) signaling is a crucial factor in the regulation of the energy balance that functions as an energy sensor in the body. The present review explores how the mTOR/S6k intracellular pathway is involved in modulating the production of different signals such as ghrelin and nesfatin-1 in the gastrointestinal tract to regulate food intake and body weight. The role of gastric mTOR signaling in different physiological processes was studied in depth through different genetic models that allow the modulation of mTOR signaling in the stomach and specifically in gastric X/A type cells. It has been described that mTOR signaling in X/A-like gastric cells has a relevant role in the regulation of glucose and lipid homeostasis due to its interaction with different organs such as liver and adipose tissue. These findings highlight possible therapeutic strategies, with the gut-brain axis being one of the most promising targets in the treatment of obesity

Clasificación de las lagunas asociadas al Canal de Castilla (Palencia) basada en la presencia de macrófitos acuáticos y emergentes

Las Lagunas Marginales del Canal de Castilla constituyen unos ecosistemas de alto valor ecológico, tanto por la variada vegetación palustre y ribereña que presentan, como por las especies faunísticas que albergan, contribuyendo a aumentar la diversidad biológica y paisajística del entorno estepario donde se ubican. A través de este estudio se ha analizado la estructura y fisonomía de las comunidades de macrófitos como base para obtener una clasificación de las lagunas. La aplicación del método de agrupación TWINSPAN establece que la permanencia y profundidad del agua son los factores diferenciadores en las lagunas marginales del Canal de Castilla y resultan determinantes de la distribución y crecimiento de la vegetación.Lagoons surrounding the Canal de Castilla constitute ecosystems of high ecological value because of the variety of their marshy and riparian vegetation as well as the faunistic species present. Thus, they contribute to a greater biological diversity and broaden the range of landscapes in the steppe environments where they are found. In this survey, the structure and composition of macrophyte communities have been analysed, as a preliminary step towards the classification of the lagoons. The application of the TWINSPAN grouping method shows that permanence and water depth are the factors that determine the distribution and development of plant communities throughout theCanal de Castilla surrounding lagoons

Caracterización fisicoquímica y estabilidad oxidativa de aceites comestibles de semillas de sacha inchi microencapsulados y secados por aspersión

The aim of this work was to obtain sacha inchi oil (SIO) microcapsules from two different species, Plukenetia volubilis L. (SIVO) and Plukenetia huayllabambana L. (SIHO), using different biopolymers as wall materials and spray drying technology. The physicochemical characteristics such as encapsulation efficiency, particle size, morphology and oxidative stability were analyzed in order to select the best formulation that could potentially be used as an ingredient in the development of functional food. Bulk SIO and four formulations were tested for each oil ecotype, using different encapsulating agents: maltodextrin (MD), Arabic gum (AG), whey protein concentrate (WPC) and modified starch HI-CAP®-100 (H). Microcapsules made of H presented the highest oxidative stability and encapsulation efficiency compared to AG, AG:MD or AG:MD:WPC formulations.El objetivo de este trabajo fue obtener microcápsulas de dos especies de aceite de sacha inchi (SIO), Plukenetia volubilis L. (SIVO) y Plukenetia huayllabambana L. (SIHO), utilizando diferentes biopolímeros como materiales de pared y la tecnología de secado por aspersión. Se analizaron tanto las características fisicoquímicas como la eficiencia de encapsulación, el tamaño de partícula, la morfología y la estabilidad oxidativa para seleccionar la mejor formulación que podría utilizarse como ingrediente en el desarrollo de alimentos funcionales. Se analizaron los aceites y cuatro formulaciones para cada ecotipo, usando diferentes agentes encapsulantes: maltodextrina (MD), goma Arábiga (AG), concentrado proteico de lactosuero (WPC) y almidón modificado HI-CAP®-100 (H). Las microcápsulas hechas con H presentaron la mayor estabilidad oxidativa y eficiencia de encapsulación en comparación con las formulaciones: AG; AG:MD o AG:MD:WPC