Contamination control engineering design guidelines for the aerospace community

Thermal control surfaces, solar arrays, and optical devices may be adversely affected by a small quantity of molecular and/or particulate contamination. What is rarely discussed is how one: (1) quantifies the level of contamination that must be maintained in order for the system to function properly, and (2) enforces contamination control to ensure compliance with requirements. This document is designed to address these specific issues and is intended to serve as a handbook on contamination control for the reader, illustrating process and methodology while providing direction to more detailed references when needed. The effects of molecular contamination on reflecting and transmitting surfaces are examined and quantified in accordance with MIL STD 1246C. The generation, transportation, and deposition of molecular contamination is reviewed and specific examples are worked to illustrate the process a design engineer can use to estimate end of life cleanliness levels required by solar arrays, thermal control surfaces, and optical surfaces. A similar process is used to describe the effect of particulate contamination as related to percent area coverage (PAC) and bi-directional reflectance distribution function (BRDF). Relationships between PAC and surface cleanliness, which include the effects of submicron sized particles, are developed and BRDF is related to specific sensor design parameters such as Point Source Transmittance (PST). The pros and cons of various methods of preventing, monitoring, and cleaning surfaces are examined and discussed

Recovering Dietary Information from Extant and Extinct Primates Using Plant Microremains

When reconstructing the diets of primates, researchers often rely on several well established methods, such as direct observation, studies of discarded plant parts, and analysis of macrobotanical remains in fecal matter. Most of these studies can be performed only on living primate groups, however, and the diets of extinct, subfossil, and fossil groups are known only from proxy methods. Plant microremains, tiny plant structures with distinctive morphologies, can record the exact plant foods that an individual consumed. They can be recovered from recently deceased and fossil primate samples, and can also be used to supplement traditional dietary analyses in living groups. Here I briefly introduce plant microremains, provide examples of how they have been successfully used to reconstruct the diets of humans and other species, and describe methods for their application in studies of primate dietary ecology

Dental wash: a problematic method for extracting microfossils from teeth (galley proofs)

A variety of microfossils, originating from plant foods, become trapped in the dental calculus matrix. Processing of dental calculus allows extraction of these microfossils. The resulting data can be used to reconstruct diet at the individual and population levels as the identification of microfossils like starch grains and phytoliths to the generic level, and sometimes to the species level, is possible. However, in some archaeological sites, dental calculus deposits do not preserve well enough to be processed. To prevent the loss of information in such cases, we present a technique, called ‘‘dental wash’’. It permits extracting microfossils from cryptic dental calculus deposits. In the two experimental archaeological cases presented herein we identified phytoliths, starch grains as well as a diatom fragment with this method, whereas in a control sample no microfossils were found. Moderate damage to the teeth was detected when they were already friable due to poor preservation. Minor damage to the surface of well-preserved teeth was observed. This indicates that the proposed method is efficient in recovering microfossils, but unacceptable because of damage to teeth. If the method can be refined, it will expand the potential of dental calculus analysis to a greater range of archeological sites

Risks: Reading Corporate Signals

https://works.swarthmore.edu/alum-books/4089/thumbnail.jp

Símbolo do coração The heart as symbol

A simbologia foi criada pelo homem pela necessidade de expressar através de objetos ou formas sua religião ou sua arte visual. Muito antes da descoberta da função de bomba impulsionadora do sangue, o coração foi tido como centro da vida, da coragem e da razão. Seu símbolo é o mais universal. De onde, e, quando, surgiu essa representação, sempre despertou a curiosidade dos historiadores, vez que pouco tem a ver com o coração anatômico. Para alguns, sua origem deve-se à semelhança com a folha da hera, que na Antiguidade representava o símbolo da imortalidade e do poder. Abordamos a curiosa origem do símbolo e a finalidade para a qual foi criado.<br>Man created symbols because he needed to express his religion or visual art through objects or shapes. Much before the heart's role in pumping blood was discovered, the organ was seen as the center of life, of courage, and of reason. It is the most universal of symbols. Historians have always been curious as to how and whence this representation appeared, since it has little to do with the anatomical organ. For some, the origin lies in the heart's resemblance to an ivy leaf, which in ancient times was a symbol of immortality and power. The article explores the curious origin of this symbol and the reason it came into being

The effect of expertise in gymnastics on postural control.

The goal of this paper was (1) to investigate if gymnasts have a more stable standing posture than experts in other sports, and (2) to determine how much gymnasts are affected by the removal of vision in different postural tasks. Six expert gymnasts and six experts in other non-gymnastic sports were asked to maintain balance in three standing postures of increasing difficulty: bipedal, unipedal, and unipedal + unstable support (i.e. 7 cm thick foam surface). Each posture was tested successively with and without vision. Based on the displacement of the center of pressure (range and mean average speed), the results showed that when visual cues were available, postural sway increased with the difficulty of the task, but both groups had comparable performance in all the tasks. When vision was removed, although both groups demonstrated larger postural sway in the unipedal tasks, this effect was less accentuated for the gymnasts. We concluded that gymnasts are able to use the remaining sensory modalities to compensate for the lack of vision in unstable postures

Opioid prescriber screening practices to detect risk for developing opioid use disorder: Qualitative perspectives from providers during the fourth wave of the opioid crisis

Little is known about how clinical providers assess risk for opioid use disorder (OUD), especially when considering prescriptions for opioid-naïve patients with acute pain. While formal screening tools exist, they are not widely used, and may not be sensitive enough to identify low-risk individuals who are susceptible to developing an OUD. Therefore, we sought to understand opioid prescribers' perspectives on their screening practices. We conducted qualitative interviews with 32 opioid prescribers across Massachusetts (11/2020–08/2021); approximately half (47%) used screening tools to identify risk for developing an OUD. We inquired about providers' risk-related screening practices before prescribing opioids, management of high-risk patients, and perspectives on barriers and facilitators to effective screening. We used a deductive content analytic approach, examining the results through a stratified lens based on use of screening methods. General prescribing and risk assessment practices did not vary by strata; however, perspectives on screening were different, as were challenges and barriers that providers identified. Recommendations from those who utilized screeners focused on standardizing and streamlining screening processes; those who did not screen suggested making risk assessments clear to avoid interpretation issues and limiting biases toward certain population groups. Findings are framed in the context of the Normalization Process Theory, addressing a lack of coherence in providers’ understanding of screeners and lack of cognitive participation and collective action across their practices surrounding OUD screening. Future research with providers should focus on strategies to integrate effective procedures around OUD prevention into their practices and methods to evaluate their impact