Noise Sources in Photometry and Radial Velocities

The quest for Earth-like, extrasolar planets (exoplanets), especially those located inside the habitable zone of their host stars, requires techniques sensitive enough to detect the faint signals produced by those planets. The radial velocity (RV) and photometric transit methods are the most widely used and also the most efficient methods for detecting and characterizing exoplanets. However, presence of astrophysical "noise" makes it difficult to detect and accurately characterize exoplanets. It is important to note that the amplitude of such astrophysical noise is larger than both the signal of Earth-like exoplanets and state-of-the-art instrumentation limit precision, making this a pressing topic that needs to be addressed. In this chapter, I present a general review of the main sources of noise in photometric and RV observations, namely, stellar oscillations, granulation, and magnetic activity. Moreover, for each noise source I discuss the techniques and observational strategies which allow us to mitigate their impact.Comment: 11 pages, 2 tables, Lecture presented at the IVth Azores International Advanced School in Space Sciences on "Asteroseismology and Exoplanets: Listening to the Stars and Searching for New Worlds" (arXiv:1709.00645), which took place in Horta, Azores Islands, Portugal in July 201

Using polyacrylamide with sprinkler irrigation to improve infiltration

Center-pivot irrigation systems often apply water at rates greater than the soil infiltration rate. Applying high molecular weight, water-soluble, anionic polyacrylamide (PAM) to the soil can improve infiltration and reduce soil erosion The objective of this study was to determine whether single and multiple PAM applications with sprinkler irrigation improved infiltration under field conditions. A two-year study conducted near Kimberly, Idaho, used a solid-set sprinkler system, and a one-year study conducted in Monte dos Alhos near Alvalade do Sado, Portugal, used a center pivot. At Kimberly, applying PAM with four irrigations (total applied PAM was 2.1 kg ha-1 in 2000 and 3.0 kg ha-1 in 2001) significantly reduced total measured runoff, from 5.9 mm (2000) and 9.2 mm (2001) for the control to 2.0 and 2.1 mm. Total measured soil erosion was also reduced from 52 and 34 kg ha 1 for the control to 21 and 5 kg ha 1 for the multiple PAM treatment. Applying similar or greater amounts of PAM with a single irrigation reduced erosion, but not runoff, compared with the control. In the Monte dos Alhos study, runoff was reduced by applying a total of 0.3 kg PAM ha 1 with a single irrigation (43 mm runoff) or three irrigations (65 mm runoff) compared with the control (111 mm runoff). Measured soil erosion was not significantly different among treatments. Applying PAM with multiple irrigations extended its effectiveness as long as the application rate was great enough to adequately stabilize the soil surface during the first irrigation

Predictive biometrics: A review and analysis of predicting personal characteristics from biometric data

Interest in the exploitation of soft biometrics information has continued to develop over the last decade or so. In comparison with traditional biometrics, which focuses principally on person identification, the idea of soft biometrics processing is to study the utilisation of more general information regarding a system user, which is not necessarily unique. There are increasing indications that this type of data will have great value in providing complementary information for user authentication. However, the authors have also seen a growing interest in broadening the predictive capabilities of biometric data, encompassing both easily definable characteristics such as subject age and, most recently, `higher level' characteristics such as emotional or mental states. This study will present a selective review of the predictive capabilities, in the widest sense, of biometric data processing, providing an analysis of the key issues still adequately to be addressed if this concept of predictive biometrics is to be fully exploited in the future

Balanços energéticos agropecuários: uma importante ferramenta como indicativo de sustentabilidade de agroecossistemas.

No Brasil, pouca atenção se tem dado às formas e caminhos com que os fluxos energéticos se distribuem nos sistemas produtivos. Na agropecuária, a atenção tem sido voltada a novas fontes de energia (biomassa) ou em tecnologia alternativa, visando a racionalização do uso de energia fóssil ou elétrica. Entretanto, a agricultura tem se desenvolvido baseada fortemente na utilização intensiva de máquinas agrícolas, com conseqüente uso de combustíveis fósseis. Um fator de estrangulamento muito forte no consumo energético geral tem sido a utilização massiva de fertilizantes derivados do petróleo nos agroecossistemas. Estudos de Balanços Energéticos visam determinar os pontos de estrangulamento energético fundamentando a busca por tecnologias poupadoras de energia, especialmente aquelas de origem fóssil (combustível, fertilizante, agrotóxicos, energia despendida na fabricação das máquinas e implementos, etc.). No Brasil, a Região Sul, é onde se encontram vários trabalhos buscando uma agricultura mais auto-sustentável, do ponto de vista da utilização da energia. Em vista da possibilidade de eventuais futuras crises energéticas, o presente trabalho procura analisar o estado-da-arte dos estudos em Balanço Energético, no Brasil e no Mundo, como uma ferramenta de indicação da sustentabilidade dos sistemas agropecuários

Metabolic Alterations in Experimental Autoimmune Encephalomyelitis in Mice: Effects of Prior Physical Exercise

Experimental autoimmune encephalomyelitis (EAE) induces significant reduction of the body mass concomitant to sickness behavior and anorexia. We investigated whether regular physical exercise prevents metabolic alterations associated with loss of the body mass occurring during an EAE inflammatory peak. Female C57BL/6 mice were assigned to the unexercised and exercise-trained groups. In four weeks, EAE was induced in half of the animals in each group, and the exercise protocol was maintained onto 10 days post-induction (10 dpi) completing 6 weeks of regular exercise (forced swimming). At 14 dpi, the relative mass of metabolic tissues, serum levels of triglycerides, cholesterol, and glucose, glycogen contents in the muscle and liver, and muscle levels of cytokines were measured. A significantly decreased clinical score associated with attenuation of the body mass loss in exercised EAE animals, as compared to the non-exercised ones, were observed. The associated metabolic parameters were not modified by this approach, although negative correlations between some parameters and clinical score at 14 dpi were observed. Although the prior program of aerobic exercise is capable of decreasing clinical score and body mass loss, it is not sufficient to crucially modify metabolic outcomes associated with inflammation at the EAE peak.Експериментальний аутоімунний енцефаломієліт (ЕАЕ) викликає істотне зменшення маси тіла, зумовлене хворобливою поведінкою та анорексією. Ми досліджували, чи можуть регулярні фізичні вправи запобігати метаболічним змінам і втраті маси тіла в перебігу запального періоду ЕАЕ. Миші-самиці лінії C57BL/6 були поділені на «нетреновану» та «треновану» групи. Через чотири тижні у половини тварин кожної групи індукували ЕАЕ, і протокол тренувань підтримувався ще 10 днів після індукції цього захворювання. Як тренування використовували примусове плавання. На 14-й день після індукції ЕАЕ у відповідній групі всі миші піддавались евтаназії; вимірювали відносну масу метаболічнозалежних тканин, рівні тригліцеридів, холестеролу та глюкози в сироватці крові, вміст глікогену в м’язах та печінці та рівні цитокінів у м’язах. У «тренованих» тварин з ЕАЕ виявлялося вірогідне зменшення оцінки інтенсивності захворювання порівняно з відповідним значенням у «нетренованих» мишей; це було асоційоване з обмеженням втрати маси тіла. У використаному варіанті експерименту зміни метаболічних параметрів у «тренованих» і «нетренованих» тварин істотно не розрізнялись, але на 14-й день спостерігалися негативні кореляції між деякими параметрами та клінічними оцінками. Отже, програма попереднього аеробного тренування здатна забезпечувати зменшення як клінічної інтенсивності ЕАЕ, так і відносної втрати маси тіла. Проте цей захід не є достатнім, щоб кардинально модифікувати метаболічні наслідки, пов’язані із запаленням на максимумі ЕАЕ

Iron(III) porphyrin covalently supported onto magnetic amino-functionalized nanospheres as catalyst for hydrocarbon and herbicide oxidations

This work describes the covalent immobilization of an ironporphyrin, 5,10,15,20- tetrakis(pentafluorophenyl)porphyrin iron(III) chloride (FeTFPP), onto maghemite/silica magnetic nanospheres covered with aminofunctionalized silica. The resulting material (γ-Fe2O3/SiO2-NHFeP) was characterized by diffuse reflectance infrared spectroscopy (DRIFTS) and UV-Vis absorption spectroscopy. The catalytic activity of this magnetic ironporphyrin was investigated in the oxidation of hydrocarbons (styrene, (Z)-cyclooctene and R-(+)-limonene) and an herbicide (simazine) by hydrogen peroxide or 3-chloroperoxybenzoic acid. Hydrocarbon and simazine oxidation reaction products were analyzed by gas chromatography (GC) and high performance liquid chromatography (HPLC), respectively. This catalytic system proved to be efficient and selective for hydrocarbon oxidation, leading to high product yields from styrene (89%), cyclooctene (71%) and R-(+)-limonene (86%). Simazine oxidation was attained with 100% selectivity for a dechlorinated product (OEAT), while several oxidation products were obtained for the same catalyst in homogeneous media. The catalyst can be easily recovered through application of an external magnetic field and washed after reaction. Catalyst reuse experiments for R-(+)-limonene oxidation have shown that the catalytic activity is kept at 90% after 10 consecutive reactions

The Science of Sungrazers, Sunskirters, and Other Near-Sun Comets

This review addresses our current understanding of comets that venture close to the Sun, and are hence exposed to much more extreme conditions than comets that are typically studied from Earth. The extreme solar heating and plasma environments that these objects encounter change many aspects of their behaviour, thus yielding valuable information on both the comets themselves that complements other data we have on primitive solar system bodies, as well as on the near-solar environment which they traverse. We propose clear definitions for these comets: We use the term near-Sun comets to encompass all objects that pass sunward of the perihelion distance of planet Mercury (0.307 AU). Sunskirters are defined as objects that pass within 33 solar radii of the Sun’s centre, equal to half of Mercury’s perihelion distance, and the commonly-used phrase sungrazers to be objects that reach perihelion within 3.45 solar radii, i.e. the fluid Roche limit. Finally, comets with orbits that intersect the solar photosphere are termed sundivers. We summarize past studies of these objects, as well as the instruments and facilities used to study them, including space-based platforms that have led to a recent revolution in the quantity and quality of relevant observations. Relevant comet populations are described, including the Kreutz, Marsden, Kracht, and Meyer groups, near-Sun asteroids, and a brief discussion of their origins. The importance of light curves and the clues they provide on cometary composition are emphasized, together with what information has been gleaned about nucleus parameters, including the sizes and masses of objects and their families, and their tensile strengths. The physical processes occurring at these objects are considered in some detail, including the disruption of nuclei, sublimation, and ionisation, and we consider the mass, momentum, and energy loss of comets in the corona and those that venture to lower altitudes. The different components of comae and tails are described, including dust, neutral and ionised gases, their chemical reactions, and their contributions to the near-Sun environment. Comet-solar wind interactions are discussed, including the use of comets as probes of solar wind and coronal conditions in their vicinities. We address the relevance of work on comets near the Sun to similar objects orbiting other stars, and conclude with a discussion of future directions for the field and the planned ground- and space-based facilities that will allow us to address those science topics