Analysis of navigation performance for the Earth Observing System (EOS) using the TDRSS Onboard Navigation System (TONS)

Use of the Tracking and Data Relay Satellite System (TDRSS) Onboard Navigation System (TONS) was proposed as an alternative to the Global Positioning System (GPS) for supporting the Earth Observing System (EOS) mission. The results are presented of EOS navigation performance evaluation with respect to TONS based orbit, time, and frequency determination (OD/TD/FD). Two TONS modes are considered: one uses scheduled TDRSS forward link service to derive one way Doppler tracking data for OD/FD support (TONS-I); the other uses an unscheduled navigation beacon service (proposed for Advanced TDRSS) to obtain pseudorange and Doppler data for OD/TD/FD support (TONS-II). Key objectives of the analysis were to evaluate nominal performance and potential sensitivities, such as suboptimal tracking geometry, tracking contact scheduling, and modeling parameter selection. OD/TD/FD performance predictions are presented based on covariance and simulation analyses. EOS navigation scenarios and the contributions of principal error sources impacting performance are also described. The results indicate that a TONS mode can be configured to meet current and proposed EOS position accuracy requirements of 100 and 50 m, respectively

What’s Trust Got to Do with It? Exploring Agricultural Science Podcast Producers’, Guests’, and Listeners’ Perceptions and Levels of Trust in Science

Little research to this point has examined food, agricultural, natural resource, and human science (FANRHS) podcast creation, the trustworthiness of the information presented, and the credibility of the individuals speaking on the podcast. The purpose of this study was to explore the level of trust in science of FANRHS podcast producers, guests, and listeners. The study followed an explanatory sequential mixed-method design beginning with an online survey instrument to measure trust in science and later, semi-structured interviews to further explore participants’ perceptions of trust and trust in science. Results showed participants had moderate to moderately high levels of trust in science. The study produced recommendations for podcast producers and guests regarding how to increase the credibility of their content and how to better foster science engagement. Future research should delineate trust based on various sub-topics within FANRHS and further explore specific communication tactics and framing strategies to create trusting relationships with podcast listeners

Automated maneuver planning using a fuzzy logic algorithm

Spacecraft orbital control requires intensive interaction between the analyst and the system used to model the spacecraft trajectory. For orbits with right mission constraints and a large number of maneuvers, this interaction is difficult or expensive to accomplish in a timely manner. Some automation of maneuver planning can reduce these difficulties for maneuver-intensive missions. One approach to this automation is to use fuzzy logic in the control mechanism. Such a prototype system currently under development is discussed. The Tropical Rainfall Measurement Mission (TRMM) is one of several missions that could benefit from automated maneuver planning. TRMM is scheduled for launch in August 1997. The spacecraft is to be maintained in a 350-km circular orbit throughout the 3-year lifetime of the mission, with very small variations in this orbit allowed. Since solar maximum will occur as early as 1999, the solar activity during the TRMM mission will be increasing. The increasing solar activity will result in orbital maneuvers being performed as often as every other day. The results of automated maneuver planning for the TRMM mission will be presented to demonstrate the prototype of the fuzzy logic tool

Podcasts in Production: An Examination of Current and Best Practices for Agricultural and Natural Resource Podcast Producers

Little research has been done on the production and use of podcasts in the fields of food, agriculture, natural resource, or human sciences (FANRHS). Currently, there is limited information for best practices on creating an effective FANRHS podcast to reach a target public audience. The purpose of this study was to examine existing practices and experiences of FANRHS podcast producers. The findings of this study will be of interest to organizations, institutions, and individuals who currently produce or are interested in producing an educational or science-based podcast. This study provided foundational information on podcast creation and maintenance. Future research should explore optimal podcast formats and content design to influence listeners’ perception and knowledge level on FANRHS science topics

Multi-Body Orbit Architectures for Lunar South Pole Coverage

A potential ground station at the lunar south pole has prompted studies of orbit architectures that ensure adequate coverage. Constant communications can be achieved with two spacecraft in different combinations of Earth-Moon libration point orbits. Halo and vertical families, as well as other orbits near L1 and L2 are considered. The investigation includes detailed results using nine different orbits with periods ranging from 7 to 16 days. Natural solutions are generated in a full ephemeris model, including solar perturbations. A preliminary station-keeping analysis is also completed

Trajectory design strategies that incorporate invariant manifolds and swingby

Libration point orbits serve as excellent platforms for scientific investigations involving the Sun as well as planetary environments. Trajectory design in support of such missions is increasingly challenging as more complex missions are envisioned in the next few decades. Software tools for trajectory design in this regime must be further developed to incorporate better understanding of the solution space and, thus, improve the efficiency and expand the capabilities of current approaches. Only recently applied to trajectory design, dynamical systems theory now offers new insights into the natural dynamics associated with the multi-body problem. The goal of this effort is the blending of analysis from dynamical systems theory with the well established NASA Goddard software program SWINGBY to enhance and expand the capabilities for mission design. Basic knowledge concerning the solution space is improved as well

Can Anyone Hear Us? An Exploration of Echo Chambers at a Land-Grant University

Faculty at land-grant universities are expected to engage in some form of Extension, or science communication, as part of the land-grant mission. However, critics have claimed these institutions are out of touch with their stakeholders’ needs and faculty mainly communicate with others in academia. This engagement with a homogenous group reflects the concepts of echo chambers, where people are only exposed to information that aligns with their beliefs and current knowledge and discredit opposing information. An explanatory mixed-methods design was used to understand land-grant faculty’s engagement in echo chambers. A survey was distributed to a census of tenure-track faculty in the University of Florida’s Institute of Food and Agricultural Sciences to understand respondents’ engagement in echo chambers. Follow-up interviews were conducted with 13 of the survey respondents to further explore their audiences and channels used in science communication to understand their engagement in echo chambers. Survey results indicated faculty did not necessarily participate in echo chambers, but they also did not contribute to an open communication network. However, the interviews found participants were interested in reaching new audiences yet struggled to communicate with stakeholders. The participants also reported wanting to find alternative channels to peer reviewed journals to help disseminate their work. The findings from this study indicated faculty contributed to a type of echo chamber, but rather than viewing their stakeholders’ opinions as false, they simply did not hear the opinions. Agricultural communicators should work with land-grant faculty administrators to identify appropriate audiences and channels for science communication

Growing with the market : how changing conditions during market growth affect formation and evolution of interfirm ties

Research Summary: Market conditions are known to matter for firm performance and growth. This study explores how changing levels of uncertainty and competition affect interfirm ties of entrepreneurial firms as markets transition from nascent to growth stage. Tracing 6 entrepreneurial game publishers during the growth stage of the US wireless gaming market, the findings reveal that in a growth stage market, as uncertainty decreases, certain ties of entrepreneurial firms are terminated. First, existing partners may cut ties and become competitors after entering the market directly. This is a “winner's curse” as more successful firms are more likely to entice their partners to enter the market directly. Second, ties may be terminated as prominent firms that are “overwhelmed” with too many partners cut ties with low to mediocre performance while their remaining partners enter a positive spiral of tie strength and performance. Finally, as uncertainty decreases, new firms may enter the market as competitors to prominent firms. While entrepreneurial firms with high and low performing ties to prominent partners may find ties with these new entrants attractive, those with mediocre ties to few prominent partners find this move too risky and wait for a first mover to legitimate it. Overall, the findings show that changing levels of uncertainty and competition in growth stage markets can have different consequences for firms due to heterogeneity in their ties and power relative to partners. The findings provide several contributions to literature regarding the relationship between interfirm ties, firm performance, and market evolution. Managerial Summary: Based on interviews at 6 entrepreneurial game publishers in the US and their partners, this study shows how changing levels of uncertainty and competition in growing markets can have different consequences for firms based on the different types of alliances in their portfolio and their power relative to partners. The findings highlight the importance of managing partners differently based on alliance type and goal of the partner. They advocate remaining flexible in alliance management as information asymmetries, intentions and bargaining power of partners can change and lead to abrupt alliance dissolution. They show that alliance portfolio management goes beyond a firm's capability of managing individual alliances, and provide a tool for managers to evaluate their alliance portfolios and take the necessary precautions

Light controls phospholipase A2α and β gene expression in Citrus sinensis

The low-molecular weight secretory phospholipase A2α (CssPLA2α) and β (CsPLA2β) cloned in this study exhibited diurnal rhythmicity in leaf tissue of Citrus sinensis. Only CssPLA2α displayed distinct diurnal patterns in fruit tissues. CssPLA2α and CsPLA2β diurnal expression exhibited periods of approximately 24 h; CssPLA2α amplitude averaged 990-fold in the leaf blades from field-grown trees, whereas CsPLA2β amplitude averaged 6.4-fold. Diurnal oscillation of CssPLA2α and CsPLA2β gene expression in the growth chamber experiments was markedly dampened 24 h after transfer to continuous light or dark conditions. CssPLA2α and CsPLA2β expressions were redundantly mediated by blue, green, red and red/far-red light, but blue light was a major factor affecting CssPLA2α and CsPLA2β expression. Total and low molecular weight CsPLA2 enzyme activity closely followed diurnal changes in CssPLA2α transcript expression in leaf blades of seedlings treated with low intensity blue light (24 μmol m−2 s−1). Compared with CssPLA2α basal expression, CsPLA2β expression was at least 10-fold higher. Diurnal fluctuation and light regulation of PLA2 gene expression and enzyme activity in citrus leaf and fruit tissues suggests that accompanying diurnal changes in lipophilic second messengers participate in the regulation of physiological processes associated with phospholipase A2 action

Efecto de la sobreexpresión de CBM-FaEXP2 en frutilla

Uno de los factores determinantes de la calidad y vida poscosecha de frutos carnosos es su firmeza, impuesta en gran medida por la resistencia mecánica que ofrece la pared celular vegetal. El fenómeno del ablandamiento de frutos es un proceso altamente regulado en el que participan diversos actores en forma concertada y redundante. Las expansinas (EXPs) son proteínas no hidrolíticas relevantes en procesos dónde es necesaria la relajación de la pared, tal como lo es el fenómeno de ablandamiento. Estas proteínas se caracterizan por presentar un módulo catalítico similar al de las glicosil-hidrolasas (carente de actividad hidrolítica) y un módulo de unión a carbohidratos (CBM) con fuerte afinidad por celulosa. En el presente trabajo se analizó el efecto de la sobreexpresión del CBM de la expansina dos de Fragaria x ananassa (FaExpa2) sobre el ablandamiento del fruto, usando Fragaria vesca cv. Hawaii 4 como sistema modelo, bajo la hipótesis de que la expresión de una proteína con la capacidad de unirse a carbohidratos, pero carente de actividad hidrolítica sobre los mismos genera una competencia por el sustrato con el resto de las enzimas involucradas en el catabolismo de la pared celular, provocando una reducción global de la degradación de la pared celular. Se analizaron distintos parámetros de calidad, la actividad expansina y poligalacturonasa en frutos transgénicos sobreexpresantes de CBM-FaEXPa2.Trabajo publicado en Castagnini, Juan Manuel; Luz Marina Zapata; Liliana Mabel Gerard (eds.). Libro de Trabajos Completos I Congreso Argentino de Biología y Tecnología Poscosecha. IX Jornadas Argentinas de Biología y Tecnología Poscosecha. Paraná: Universidad Nacional de Entre Ríos. UNER, 2018.Facultad de Ciencias Agrarias y Forestales (FCAF