Guarding Latin America’s Literary Treasures. An Interview with Melissa Guy

With over 1.2 million books, thousands of newspapers and periodicals —as well as audiovisual materials and digital sources —the Benson collection is one of the largest collections of Latin American literature in the world. The collection is housed at the University of Texas at Austin, which will be the guest of honor at the upcoming Quinta Feria Internacional del Libro de las Universitarias y los Universitarios (Filuni). At the helm of the Benson collection since 2018, Melissa Guy is also in charge of Southern Cone acquisitions for the library. In preparation for activities at Filuni, Guy shares information about the Benson collection and how it grew from its humble beginnings to its current stature. The Benson completed its centennial in 2021, and as the collection continues to grow, Guy also shares the digital plans for the Benson’s second centur

Exchange reactions on zeolites and related catalysts

The exchange of hydrocarbons with deuterium makes/useful test reactions] for studying catalytic processes and finding out what first happens when the molecules are adsorbed on the catalyst surface. The object of the present study was to examine the catalytic activity of amorphous and crystalline aluminosilicates for these reactions in order to try to elucidate the nature of the adsorbed species and compare the results with those obtained for other classes of catalysts.The exchange reactions of benzene, toluene, and m- xylene with deuterium have been studied on silica -alumina and alumina catalysts. On these catalysts the hydrogen atoms in the ring positions reacted in preference to those attached to the side groups and there were no appreciable directing effects due to the side groups. The main conclusion drawn is that these catalysts are of an acid nature although there are some differences between the results and those for the homogeneous acid catalysed exchange. Reaction mechanisms are discussed with particular reference to a possible slow step involving surface hydroxyl groups.The activity of synthetic crystalline alumino- silicates (X -type zeolites) were examined in various ion exchanged forms for hydrogen -deuterium exchange and for the reactions of ethylene, propylene, 1- butene, isobutene, isobutane and m- xylene with D20. Most of the zeolites were poor catalysts for the hydrogen -deut(;rium exchange reaction but in some cases the activity could be increased by heating in hydrogen. For the exchange of hydrocarbons with D20 the order of activities of the catalysts were CeX, LaX > NiX, CoX, Cu;) CaX > NaX. On CeX and CoX the re activities of the hydrocarbons for exchange were isobutene 1- butene, m- xylene o and p ring hydrogens) propylene > m -xyi ene m -ring hydrogen > m- xylene side group hydrogens ) ethylene, isobutane. Subsidiary experiments were also carried out to determine the variation in catalytic activity with increasing amounts of D20 and varying degrees of ion exchange.The results were interpreted in terms of ionic mechanisms which produced heterolytic splitting of hydrogen and hydrocarbon molecules on adsorption. Correlations were found to exist between the reaction parameters for propylene exchange, the charge on the zeolite cations and the trends reported for surface acidities. From thermochemical data it was shown that the ease of exchange of the hydrocarbons paralleled the ease of formation of the corresponding alkyl carbonium ions.Zeolite catalysts show more resemblance to true acid catalysts than was found for reaction on silica- alumina and alumina with the possible exception of NiX which resembles pure metals and may carry out reactions via ràidical intermediates. The nature of the active site for hydrogen-deuterium exchange and for the reactions of propylene with D₂0 are discussed. For both reactions sites other than the cation seem to be important

The Role of Somatostatin in the Regulation of Gonadotropin Secretion in Sheep

Two modes of gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH) secretion are necessary for female fertility: surge and episodic secretion. However, the neural systems that regulate these GnRH secretion patterns are still under investigation. The neuropeptide somatostatin (SST) inhibits episodic luteinizing hormone (LH) secretion in humans and sheep, and several lines of evidence suggest SST may regulate secretion during the LH surge. Neither a SST receptor 2 (SSTR2) agonist (octreotide) or antagonist (CYN154806; CYN) altered the amplitude or timing of the LH surge. Administration of CYN to intact ewes during either the breeding season or anestrus increased LH secretion and increased c-Fos in a subset of GnRH and kisspeptin cells during anestrus. To determine if these stimulatory effects are steroid-dependent or -independent, we administered CYN to ovariectomized ewes. This SSTR2 antagonist increased LH pulse frequency in ovariectomized ewes during anestrus, but not during the breeding season. The results demonstrate that SST, acting through SSTR2, inhibits episodic LH secretion, likely acting in the mediobasal hypothalamus, but action at this receptor does not alter LH surge secretion. Additionally, these data provide evidence that SST contributes to the steroid-independent suppression of LH pulse frequency during anestrus.;Potential sites for SST action in the ovine hypothalamus were investigated using immunohistochemistry to determine whether cells that produce kisspeptin (KNDy cells in the arcuate nucleus) or GnRH receive direct synaptic contact from SST fibers, and whether the amount of these inputs changes throughout the estrous cycle or by season. The majority of KNDy cells receive synaptic input (evident by presynaptic synaptophysin immunostaining) from SST cells, but the amount of these inputs did not differ among groups. A subset of GnRH cells in both the preoptic area (POA) and mediobasal hypothalamus also receive synaptic input from SST cells. A greater percentage of POA GnRH cells had SST synapses during the surge than in anestrus, the luteal or early follicular phase of the estrus cycle. The total number of synaptic inputs onto GnRH and KNDy cells was altered by phase of the estrous cycle and season, extending the hypothesis that changes in the GnRH and KNDy cell synaptic connectivity may contribute to altered gonadotropin secretion throughout the estrous cycle and between seasons.;Several lines of evidence support the hypothesis that somatostatin (SST) cells in the ventral medial nucleus (VMN) may be involved in the generation of the LH surge in sheep. In this study, we confirmed that SST cells in the VMN are activated during the LH surge using c-Fos as a marker for cellular activation. One explanation for the discrepancy between the observations of SST cell activation during the LH surge, but no effect of pharmacological manipulation of SSTR2, is that the cells that contain SST in the VMN also produce additional signaling molecules, such as nitric oxide. We used immunohistochemistry to determine that a high percentage (70-80%) of these SST cells also contain neuronal nitric oxide synthase (nNOS). Triple-label immunohistochemistry was used to determine that a greater percentage of the dual labeled SST and nNOS cells contain c-Fos during the LH surge compared to the early follicular phase. In contrast, the percentage of single labeled nNOS or SST cells that contained c-Fos did not differ between the LH surge and early follicular phase. Thus we propose that this population of SST cells in the VMN also release nitric oxide and that this transmitter contributes to the generation of the LH surge in sheep

Do Substance P and Neurokinin A Play Important Roles in the Control of LH Secretion in Ewes?

There is now general agreement that neurokinin B (NKB) acts via neurokinin-3-receptor (NK3R) to stimulate secretion of GnRH and LH in several species, including rats, mice, sheep, and humans. However, the roles of two other tachykinins, substance P (SP) and neurokinin A, which act primarily via NK1R and NK2R, respectively, are less clear. In rodents, these signaling pathways can stimulate LH release and substitute for NKB signaling; in humans, SP is colocalized with kisspeptin and NKB in the mediobasal hypothalamus. In this study, we examined the possible role of these tachykinins in control of the reproductive axis in sheep. Immunohistochemistry was used to describe the expression of SP and NK1R in the ovine diencephalon and determine whether these proteins are colocalized in kisspeptin or GnRH neurons. SP-containing cell bodies were largely confined to the arcuate nucleus, but NK1R-immunoreactivity was more widespread. However, there was very low coexpression of SP or NK1R in kisspeptin cells and none in GnRH neurons. We next determined the minimal effective dose of these three tachykinins that would stimulate LH secretion when administered into the third ventricle of ovary-intact anestrous sheep. A much lower dose of NKB (0.2 nmol) than of neurokinin A (2 nmol) or SP (10 nmol) consistently stimulated LH secretion. Moreover, the relative potency of these three neuropeptides parallels the relative selectivity of NK3R. Based on these anatomical and pharmacological data, we conclude that NKB-NK3R signaling is the primary pathway for the control of GnRH secretion by tachykinins in ewes

Towards an understanding of the social learning dynamic in the advancement of organic farming in South Africa.

Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.There is growing evidence that the way that the world produces and consumes food needs to change. There is growing public awareness of serious environmental threats (e.g. global warming, loss of biodiversity and pollution) as well as social concerns (e.g. poverty, inequality and food security). It is necessary for global agriculture to rethink its approach to food production and to find new ways of producing food that can meet the demands of the growing world population and at the same time reduce the environmental degradation caused by farming. So called green revolution technologies, resulting in high intensity, high input agriculture are damaging the very resources on which agriculture depends; soil and water. Research reveals current conventional practices to be unsustainable. There is a growing recognition, arising from the creation of new knowledge and the development of deeper understanding, that this change is necessary and urgent. Organic (or ecological) farming has emerged as a more beneficial way of producing food from a social and environmental perspective. Demand for, and production of, organic food grew steadily in the second half of the twentieth century and has increased dramatically in the twenty first century. This can largely be ascribed to social learning processes. This growth is not yet reflected in South African agriculture. Given the advantages of organic agriculture, it is necessary to consider how to accelerate its expansion. Understanding the social learning processes of organic farmers and using learning histories are useful tools to create a better understanding of how this can be achieved. The objective of this dissertation is to make use of four social learning frameworks to enhance the understanding of the social learning dynamic of organic farmers by: • Using existing baseline data from a survey of the organic farming sector to draw out the learning histories. • Developing an understanding of four social learning frameworks. • Combining the learning histories and the understanding of social learning frameworks to form a deeper understanding of the social learning dynamics in the South African organic agricultural sector. A literature review of the organic sector and of four learning frameworks (profound change, conversion of knowledge, deeper learning, and the pedagogy of adult social learning) is used to develop an understanding of the essence of organic agriculture and how people learn. Information from a survey of organic farmers in South Africa, is used to impregnate the learning frameworks in order to develop an understanding of how organic farmers in South Africa are learning Open-ended questions from the survey are analysed and interpreted based on the understanding of learning frameworks. Selected statements that reflect social learning are highlighted, incorporated into the learning frameworks and discussed to better understand how organic farmers are learning. The analysis indicates that a high proportion of organic farmers are social learners. The four frameworks demonstrate that many organic farmers see their role as more than just providers of food. They also see themselves as custodians of the land with a deep concern for the environment. Fewer organic farmers demonstrate an understanding of social issues. Those that did showed a clear understanding of the need to integrate social considerations into food production. Networking and sharing of learning are important methods of knowledge creation among organic farmers as a result of the limited research and support for organic farmers in South Africa. Recommendations to accelerate and understand the learning by organic farmers and consumers are provided. Future research is suggested in order to investigate how to assist organic and conventional farmers to better understand learning, identify how learning can be enhanced or retarded, and actively engage in learning that facilitates knowledge creation