Interchange reconnection as the source of the fast solar wind within coronal holes.

The fast solar wind that fills the heliosphere originates from deep within regions of open magnetic field on the Sun called 'coronal holes'. The energy source responsible for accelerating the plasma is widely debated; however, there is evidence that it is ultimately magnetic in nature, with candidate mechanisms including wave heating1,2 and interchange reconnection3-5. The coronal magnetic field near the solar surface is structured on scales associated with 'supergranulation' convection cells, whereby descending flows create intense fields. The energy density in these 'network' magnetic field bundles is a candidate energy source for the wind. Here we report measurements of fast solar wind streams from the Parker Solar Probe (PSP) spacecraft6 that provide strong evidence for the interchange reconnection mechanism. We show that the supergranulation structure at the coronal base remains imprinted in the near-Sun solar wind, resulting in asymmetric patches of magnetic 'switchbacks'7,8 and bursty wind streams with power-law-like energetic ion spectra to beyond 100 keV. Computer simulations of interchange reconnection support key features of the observations, including the ion spectra. Important characteristics of interchange reconnection in the low corona are inferred from the data, including that the reconnection is collisionless and that the energy release rate is sufficient to power the fast wind. In this scenario, magnetic reconnection is continuous and the wind is driven by both the resulting plasma pressure and the radial Alfvénic flow bursts.

Probing the energetic particle environment near the Sun.

NASA's Parker Solar Probe mission1 recently plunged through the inner heliosphere of the Sun to its perihelia, about 24 million kilometres from the Sun. Previous studies farther from the Sun (performed mostly at a distance of 1 astronomical unit) indicate that solar energetic particles are accelerated from a few kiloelectronvolts up to near-relativistic energies via at least two processes: 'impulsive' events, which are usually associated with magnetic reconnection in solar flares and are typically enriched in electrons, helium-3 and heavier ions2, and 'gradual' events3,4, which are typically associated with large coronal-mass-ejection-driven shocks and compressions moving through the corona and inner solar wind and are the dominant source of protons with energies between 1 and 10 megaelectronvolts. However, some events show aspects of both processes and the electron-proton ratio is not bimodally distributed, as would be expected if there were only two possible processes5. These processes have been very difficult to resolve from prior observations, owing to the various transport effects that affect the energetic particle population en route to more distant spacecraft6. Here we report observations of the near-Sun energetic particle radiation environment over the first two orbits of the probe. We find a variety of energetic particle events accelerated both locally and remotely including by corotating interaction regions, impulsive events driven by acceleration near the Sun, and an event related to a coronal mass ejection. We provide direct observations of the energetic particle radiation environment in the region just above the corona of the Sun and directly explore the physics of particle acceleration and transport.

An integrated time-of-flight versus residual energy subsystem for a compact dual ion composition experiment for space plasmas.

We have developed a novel concept for a Compact Dual Ion Composition Experiment (CoDICE) that simultaneously provides high quality plasma and energetic ion composition measurements over 6 decades in ion energy in a wide variety of space plasma environments. CoDICE measures the two critical ion populations in space plasmas: (1) mass and ionic charge state composition and 3D velocity and angular distributions of ∼10 eV/q-40 keV/q plasma ions­CoDICE-Lo and (2) mass composition, energy spectra, and angular distributions of ∼30 keV-10 MeV energetic ions­CoDICE-Hi. CoDICE uses a common, integrated Time-of-Flight (TOF) versus residual energy (E) subsystem for measuring the two distinct ion populations. This paper describes the CoDICE design concept, and presents results of the laboratory tests of the TOF portion of the TOF vs. E subsystem, focusing specifically on (1) investigation of spill-over and contamination rates on the start and stop microchannel plate (MCP) anodes vs. secondary electron steering and focusing voltages, scanned around their corresponding model-optimized values, (2) TOF measurements and resolution and angular resolution, and (3) cross-contamination of the start and stop MCPs' singles rates from CoDICE-Lo and -Hi, and (4) energy resolution of avalanche photodiodes near the lower end of the CoDICE-Lo energy range. We also discuss physical effects that could impact the performance of the TOF vs. E subsystem in a flight instrument. Finally, we discuss advantages of the CoDICE design concept by comparing with capabilities and resources of existing flight instruments.

The SupraThermal Ion Monitor for space weather predictions.

Measurement of suprathermal energy ions in the heliosphere has always been challenging because (1) these ions are situated in the energy regime only a few times higher than the solar wind plasma, where intensities are orders of magnitude higher and (2) ion energies are below or close to the threshold of state-of-art solid-state detectors. Suprathermal ions accelerated at coronal mass ejection-driven shocks propagate out ahead of the shocks. These shocks can cause geomagnetic storms in the Earth's magnetosphere that can affect spacecraft and ground-based power and communication systems. An instrument with sufficient sensitivity to measure these ions can be used to predict the arrival of the shocks and provide an advance warning for potentially geo-effective space weather. In this paper, we present a novel energy analyzer concept, the Suprathermal Ion Monitor (STIM) that is designed to measure suprathermal ions with high sensitivity. We show results from a laboratory prototype and demonstrate the feasibility of the concept. A list of key performances is given, as well as a discussion of various possible detectors at the back end. STIM is an ideal candidate for a future space weather monitor in orbit upstream of the near-earth environment, for example, around L1. A scaled-down version is suitable for a CubeSat mission. Such a platform allows proofing the concept and demonstrating its performance in the space environment.

The entrance system laboratory prototype for an advanced mass and ionic charge composition experiment.

Electrostatic analyzers (ESA) have been used extensively for the characterization of plasmas in a variety of space environments. They vary in shape, geometry, and size and are adapted to the specific particle population to be measured and the configuration of the spacecraft. Their main function is to select the energy per charge of the particles within a passband. An energy-per-charge range larger than that of the passband can be sampled by varying the voltage difference between the ESA electrodes. The voltage sweep takes time and reduces the duty cycle for a particular energy-per-charge passband. Our design approach for an advanced mass and ionic charge composition experiment (AMICCE) has a novel electrostatic analyzer that essentially serves as a spectrograph and selects ions simultaneously over a broad range of energy-per-charge (E/q). Only three voltage settings are required to cover the entire range from approximately 10 to 270 keV/q, thus dramatically increasing the product of the geometric factor times the duty cycle when compared with other instruments. In this paper, we describe the AMICCE concept with particular emphasis on the prototype of the entrance system (ESA and collimator), which we designed, developed, and tested. We also present comparisons of the laboratory results with electrostatic simulations.

Nutritional needs assessment of rural agricultural migrants of southern Brazil: designing, implementing and evaluating a nutrition education program.

A nutritional needs assessment was conducted among rural agricultural migrant women (target group) and children (less than 5 years). The study was conducted in Vila Diogo, a slum located on the periphery of Nuporanga, a village in Sao Paulo state, Brazil. A nutrition education program was designed on the basis of evidence obtained from demographic/socioeconomic information of the study population and a nutritional needs assessment of women (target group) and children less than 5 years of age. The nutritional needs assessment consisted of anthropometry, dietary assessment, and nutrition knowledge, attitudes, and beliefs questionnaires. Formative and summative evaluation of the nutrition education program, using appropriately selected criteria and comparisons of nutrition knowledge scores before and after the program, were used to determine program effectiveness. Major findings of the study were: Diets of Vila Diogo residents were generally simplistic, consisting primarily of rice, beans, and coffee with sugar. Vila Diogo women appeared to be at a relatively high risk for vitamin A, iron, calcium, ascorbic, and riboflavin deficiencies, based on comparisons of 24-hour dietary intake data with FAO recommendations. Children (2-5 years) appeared at high risk for vitamin A, iron, and ascorbic acid deficiencies, based on comparisons of 24-hour dietary intake data with FAO recommendations. All children less than 5 years of age had been breast-fed at birth, but more than one half of children had been weaned by the third month. Infant feeding practices during fever and diarrhea were nutritionally detrimental. Women generally recognized a relationship between dietary intake during pregnancy and fetal nourishment. Using weight-for-height index, a significant number of women were probably undernourished; a small percentage of women, however, were overweight or obese. Although children less than 5 years of age did not generally appear malnourished, a relatively large number were stunted in growth. Although Vila Diogo women reported many food taboos during various physiological states (menstruation, pregnancy, immediately post partum, lactation), relatively few food taboos had potentially negative nutritional consequences. For women who participated in the nutrition education program, nutrition knowledge scores after the program showed improvement which was statistically significant at alpha = 0.05, using Wilcoxon signed rank test.

Marginal malnutrition and reduced physical work capacity of migrant adolescent boys in Southern Brazil.

We measured the effect of marginal malnutrition on physical work capacity of adolescent children of agricultural migrant workers in Southern Brazil. Nutritional status was evaluated using 24-h dietary recall. Body size was evaluated anthropometrically. Biochemical assessments were also made. Physical work capacity (PWC170) was assessed by measuring heart rate, blood lactic acid levels, and oxygen consumption during submaximal bicycle ergometer work. The same tests were also carried out on a comparable group of local well-to-do boys of the same age in the same community who served as controls. The dietary results suggest that adolescent boys of migrant families were marginally malnourished. Their physical growth and development were retarded by at least 1 yr. They had significantly lower reserves of body fat and less muscle mass when compared with controls. Their Hb levels were normal. At the submaximal work loads measured (0, 25, 50, 75 W) the migrant children exhibited similar oxygen consumption and gross exercise efficiency as the control children, but achieved this work at a higher percentage of their maximum work capacity as shown by significantly higher heart rates for the same oxygen consumption. Higher blood lactic acid levels in the migrant children suggest that the available muscle mass was under greater stress to accomplish the same task. PWC170 was reduced one-third in the migrant children (migrant 643 +/- 162 kpm/min, control 905 +/- 345 kpm/min; p less than 0.005). These differences were largely associated with weight (migrant 20.6 +/- 5.9 kpm/min; control 18.8 +/- 4.3 kpm/kg/min; p greater than 0.1). These observations suggest that marginal as well as severe malnutrition affect physical work capacity at levels low enough to affect growth and development.

Anthropometric and cycloergometric assessment of the nutritional status of the children of agricultural migrant workers in Southern Brazil.

In our survey of the food habits and nutritional status of "Boia-Fria" agricultural migrant workers in Southern Brazil, a special project was undertaken to assess the influence of socioeconomic and dietary deprivation on the physical growth and development and physical performance of their children. Four hundred fifty-five children in Boia-Fria families from Vila Recreio, a periurban slum of Ribeirao Preto located in the interior of the state of Sao Paulo, were examined for body weight, standing height, mid-upper arm muscle circumference, and head circumference. For comparison, 475 children from "Vita et Pax", a private school attended primarily by children of well-to-do families from the city of Ribeirao Preto, were also examined using similar anthropometric procedures. A small group of selected Boia-Fria children and their well-to-do counterparts were subjected to ergometric-cum-electrocardiographic testing for submaximal physical work performance. The overall results of this comparative study indicate that the physical growth and development and the physical performance of the Boia-Fria children are significantly lower than their well-to-do counterparts. It is suggested that the poor anthropometric and ergometric status of the Boia-Fria children is a reflection of poor dietary habits and socioeconomic deprivation prevalent among the agricultural migrant workers and poor periurban populations of Brazil.