Drew Conroy Professor, TSAS, travels to Sub-Saharan Africa

In June and July, I spent 3 weeks in five countries in Sub-Saharan Africa. These included Kenya, Rwanda, The Democratic Republic of the Congo (DRC), Tanzania and Namibia. This incredible journey included attending an agricultural forum, visiting an agricultural development project, for which I have been an advisor for some years, checking out sabbatical possibilities in Tanzania and Rwanda, and finally visiting UNH undergraduate student, Alicia Walsh at the Cheetah Conservation Fund in Otjiwarongo, Namibia, with the financial help of the UNH Center for International Education

The Economic Importance of Draught Oxen on Small Farms in Namibia\u27s Eastern Caprivi Region

The main aim of this study was to analyse and document the value of smallholder farmers’ use of Draught Animal Power (DAP) systems in the Eastern Caprivi Region and to test the economic viability of DAP usage versus using tractors. This study applied Rapid Rural Appraisal techniques (RRA), including a survey. Semi-structured interviews were conducted with 312 farmers at their farms and data was gathered on the use of and economics related to the draught animal power system. Crop enterprise budgets, project reports, expert opinions and group discussions were analysed. The research found that the use of animal power performs better in terms of physical productivity per ha compared to tractor usage. Furthermore, agricultural production in Sibinda village area, with the use of oxen outperformed the other systems when it was evaluated with parametric analysis. From a financial perspective, faremrs in Sibinda and Linyanti using oxen ranked above their counterparts using tractors. Further, the exercise indicated that farmers are facing a multitude of challenges such as damage incurred from wild animals and high input costs. There were many difficulties facing the next generation in entering commericial agricultural production in Caprivi within the current cost-price squeeze environment. Therefore, understanding the role draught oxen power can play as a tool to increase the level of success for new farmers’ in agricultural production and management was noted

Are Halo and Galaxy Formation Histories Correlated?

The properties of dark matter halos, including mass growth, correlate with larger scale environment at fixed mass, an effect known as assembly bias. However, whether this environmental dependence manifests itself in galaxy properties remains unclear. We apply a group-finding algorithm to DR7 of the SDSS to estimate the halo mass of each galaxy and to decompose galaxies into those that exist at the centers of distinct halos and those that orbit as satellites within larger halos. Using the 4000-A break as a measure of star formation history, we examine the correlation between the quenched fraction of galaxies, f_q, and large-scale environment, rho. At all galaxy magnitudes, there is a positive, monotonic relationship between f_q and rho. We use the group catalog to decompose this correlation into the contribution from central and satellite galaxies as a function of halo mass. Because satellites are more likely to be quenched than central galaxies, the observed f_q-rho correlation is primarily due to variations of the halo mass function with environment, which causes a larger fraction of satellite galaxies at high rho. For low-mass central galaxies (Mgal <~ 10^10.0 Msol/h^2), there is no correlation between f_q and rho. These results are inconsistent with the strong assembly bias of dark matter halos seen in this mass regime if recent galaxy growth at all correlates with recent halo growth, as we demonstrate through a high resolution N-body simulation. We also find that the mean stellar age of quenched central galaxies is independent of rho at fixed Mgal, while the formation times of low mass halos vary significantly. We conclude that the processes that halt the star formation of low mass central galaxies are not correlated to the formation histories of their host halos, and old galaxies do not reside preferentially in old halos. (Abridged)Comment: 21 pages, submitted to MNRA

Maasai oxen, agriculture and land use change in Monduli District, Tanzania

This dissertation examines the sustainability of the use of oxen by the Maasai and Arusha (WaArusha) people, in Monduli District, Tanzania. Traditionally pastoralists, the Maasai are undergoing a social and agricultural transformation process of sedentarization in this region. The villages included in the case study were Arkatan, Engaruka, Esilalei, Lashaine, Lendikenya, Lolkisale, Losirwa, Mbuyuni, Mswakini, and Selela. Using semi-structured interviews the heads of 130 Maasai homesteads (bomas), as well as, other informants were interviewed. The history, issues of technology transfer and future prospects of animal traction were examined, as well as, the obstacles and constraints facing the Maasai in their adoption of this technology. This case study also documents and compares the agricultural development and cropping strategies of the Maasai and WaArusha people related to the adoption and sustainable use of animal traction. The adoption of oxen and other forms of agricultural power, including tractors, by the Maasai has transformed their view of land tenure, their access to common grazing areas, and their ability to share grazing resources with wildlife. Adopting well-known agricultural development strategies, the Maasai have also tried to maintain their livestock keeping and pastoral culture. Monduli District, located in Northern Tanzania, is adjacent to many wildlife areas and National Parks, including Lake Manyara National Park, Tarangire National Park, Arusha National Park, and the Ngorongoro Conservation Area. Nearby Maasai grazing areas have been considered important wildlife corridors. The proximity to these wildlife areas has created a situation where large numbers of wildlife frequently pass through and raid crop fields. The Maasai and WaArusha people face a shrinking land base, reducing their ability to survive by pastoralism alone. Crop growing has become an important part of their economic survival. The landscape in the research area has changed dramatically in the last 15 years. This land use change, particularly in highland areas, has created environmental problems, such as overgrazing, soil erosion, as well as, decreased vegetative cover leading to lower soil moisture levels. The result has been decreased crop yields in many areas, with increased social and wildlife conflicts, as well as, rampant environmental problems

Oxen: Status, Uses and Practices in the U.S.A., Encouraging a Historic Tradition to Thrive

Oxen in the United States of America have played an important role throughout its history. Unlike other countries,oxen were never completely given up for horses, mules, or tractors. Instead, the culture of keeping oxen has been maintained by a small group of teamsters in the North- eastern states collectively called New England. Their continued presence has been largely due to agricultural fairs and exhibitions where they have been used in competition for the last 200 years. Ox teamsters were sur- veyed in 2021via social media using Qualtrics. The 423 ox teamsters responding owned 1791 oxen in 39 states, with the majority of oxen and teamsters in Maine, New Hampshire, Vermont, Connecticut, Massachu- setts and New York respectively. The gender breakdown of ox teamsters was 59 % men, 40 % women. Results showed 257 teamsters used their oxen for farm work, 213 for exhibitions and parades, 191 for logging, 173 for recreation, 165 for competition showing, 144 for competition pulling, 85 at living history farms and in historic settings, and 18 in television and movies. Teamsters worked oxen an average of 7 hours/week and 89 % train the oxen as calves. 289 people learned to train from friends, 211 from family, 202 from books, 158 from organizations related to oxen, 156 from the Internet, 152 in the 4-H program, 129 from videos, 94 at hands- on workshops, 54 from magazines and 42 from living history farms. More than 20 breeds of cattle were used as oxen with Milking Shorthorns (11.9 %), Holstein-Friesians (10.9 %), Chianina (9.6 %) and Brown Swiss (9.3 %) being the most numerous

Ox Yokes: Culture, Comfort and Animal Welfare

Three yoking systems are used globally to capture the power of oxen. These are the head yoke, withers yoke, and neck yoke. Each system has its strengths and weaknesses, with culture and cattle playing a role in the adoption and use of each system. The neck yoke system offers important lessons in understanding animal comfort and yoke design. Despite its success, the neck yoke should not be universally adopted, nor should it be universally promoted. However ignoring the lessons learned in North America over the last 400 years would ignore animals and teamsters who perfected this system and learned to maximize animal comfort and performance. Using history, research in Africa, as well as farm and competition experience from the United States and Canada, this paper addresses improving animal comfort, performance and welfare by understanding and appreciating yoking systems for oxen

Galaxy evolution in groups and clusters: satellite star formation histories and quenching timescales in a hierarchical Universe

Satellite galaxies in groups and clusters are more likely to have low star formation rates (SFR) and lie on the red-sequence than central (field) galaxies. Using galaxy group/cluster catalogs from SDSS DR7, together with a cosmological N-body simulation to track satellite orbits, we examine the star formation histories and quenching timescales of satellites of M_star > 5 x 10^9 M_sun at z=0. We first explore satellite infall histories: group preprocessing and ejected orbits are critical aspects of satellite evolution, and properly accounting for these, satellite infall typically occurred at z~0.5, or ~5 Gyr ago. To obtain accurate initial conditions for the SFRs of satellites at their time of first infall, we construct an empirical parametrization for the evolution of central galaxy SFRs and quiescent fractions. With this, we constrain the importance and efficiency of satellite quenching as a function of satellite and host halo mass, finding that satellite quenching is the dominant process for building up all quiescent galaxies at M_star < 10^10 M_sun. We then constrain satellite star formation histories, finding a 'delayed-then-rapid' quenching scenario: satellite SFRs evolve unaffected for 2-4 Gyr after infall, after which star formation quenches rapidly, with an e-folding time of < 0.8 Gyr. These quenching timescales are shorter for more massive satellites but do not depend on host halo mass: the observed increase in satellite quiescent fraction with halo mass arises simply because of satellites quenching in a lower mass group prior to infall (group preprocessing), which is responsible for up to half of quenched satellites in massive clusters. Because of the long time delay before quenching starts, satellites experience significant stellar mass growth after infall, nearly identical to central galaxies. This fact provides key physical insight into the subhalo abundance matching method.Comment: 25 pages, 13 figures. Accepted for publication in MNRAS, matches published versio

A power-saving modulation technique for time-of-flight range imaging sensors

Time-of-flight range imaging cameras measure distance and intensity simultaneously for every pixel in an image. With the continued advancement of the technology, a wide variety of new depth sensing applications are emerging; however a number of these potential applications have stringent electrical power constraints that are difficult to meet with the current state-of-the-art systems. Sensor gain modulation contributes a significant proportion of the total image sensor power consumption, and as higher spatial resolution range image sensors operating at higher modulation frequencies (to achieve better measurement precision) are developed, this proportion is likely to increase. The authors have developed a new sensor modulation technique using resonant circuit concepts that is more power efficient than the standard mode of operation. With a proof of principle system, a 93–96% reduction in modulation drive power was demonstrated across a range of modulation frequencies from 1–11 MHz. Finally, an evaluation of the range imaging performance revealed an improvement in measurement linearity in the resonant configuration due primarily to the more sinusoidal shape of the resonant electrical waveforms, while the average precision values were comparable between the standard and resonant operating modes

The Extended IRTF Spectral Library: Expanded coverage in metallicity, temperature, and surface gravity

We present a $0.7-2.5\mu m$ spectral library of 284 stars observed with the medium-resolution infrared spectrograph, SpeX, at the 3.0 meter NASA Infrared Telescope Facility (IRTF) on Maunakea, Hawaii. This library extends the metallicity range of the IRTF Cool Star library beyond solar metallicity to $-1.7 <$ [Fe/H] $< 0.6$. All of the observed stars are also in the MILES optical stellar library, providing continuous spectral coverage for each star from $0.35-2.5\mu m$. The spectra are absolute flux calibrated using Two Micron All Sky Survey photometry and the continuum shape of the spectra is preserved during the data reduction process. Synthesized $JHK_S$ colors agree with observed colors at the $1-2\%$ level, on average. We also present a spectral interpolator that uses the library to create a data-driven model of spectra as a function of $teff$, $logg$, and [Fe/H]. We use the library and interpolator to compare empirical trends with theoretical predictions of spectral feature behavior as a function of stellar parameters. These comparisons extend to the previously difficult to access low-metallicity and cool dwarf regimes, as well as the previously poorly sampled super-solar metallicity regime. The library and interpolator are publicly available.Comment: Accepted to ApJS. The website making the data publicly available will be available soon. For those interested in the meantime, contact the first autho