A Geometric Flow Approach for Segmentation of Images with Inhomongeneous Intensity and Missing Boundaries

Image segmentation is a complex mathematical problem, especially for images that contain intensity inhomogeneity and tightly packed objects with missing boundaries in between. For instance, Magnetic Resonance (MR) muscle images often contain both of these issues, making muscle segmentation especially difficult. In this paper we propose a novel intensity correction and a semi-automatic active contour based segmentation approach. The approach uses a geometric flow that incorporates a reproducing kernel Hilbert space (RKHS) edge detector and a geodesic distance penalty term from a set of markers and anti-markers. We test the proposed scheme on MR muscle segmentation and compare with some state of the art methods. To help deal with the intensity inhomogeneity in this particular kind of image, a new approach to estimate the bias field using a fat fraction image, called Prior Bias-Corrected Fuzzy C-means (PBCFCM), is introduced. Numerical experiments show that the proposed scheme leads to significantly better results than compared ones. The average dice values of the proposed method are 92.5%, 85.3%, 85.3% for quadriceps, hamstrings and other muscle groups while other approaches are at least 10% worse.Comment: Presented at CVIT 2023 Conference. Accepted to Journal of Image and Graphic

Evaluation of aflatoxin contamination of stored maize in the Brong-Ahafo region of Ghana: Poster

This study assessed the aflatoxin contamination and the presence of fungi in three maize varieties (Obatanpa, Abontem and Aburohemaa) stored using different storage methods namely storage in hermetic bags, woven polypropylene sacks and local crib in the Nkoranza-South district of the Brong-Ahafo region of Ghana. A factorial design arrangement was laid out in a randomized complete block design (RCBD). The isolation and identification of fungal pathogens associated with maize samples before and after storage were carried out on potato dextrose agar (PDA). Total flatoxin levels in the three maize varieties was determined by the use of enzyme-linked immunosorbent assay (ELISA) at 450 nm wavelength. Six fungi species were identified in the maize namely: Aspergillus flavus, Penicillium sp, Fusarium sp., Lasiodiplodia theobromae, Colletotrichum gleosporioides and Rhizopus. Before storage, Abontem variety recorded significantly higher (p < 0.05) total aflatoxin levels (113.56 ppb) compared to Obatanpa (2.91 ppb) and Aburohemaa (2.96 ppb). Maize samples stored in the polypropylene sack established significantly higher (p < 0.05) total aflatoxin levels of 82.9 ppb compared to hermetic bags (48.9 ppb) and local crib (48.9 ppb) after storage for six months. Aflatoxin levels under the interactive effect of variety and storage method was significant (p < 0.05). Overall storage of maize in hermetic bags significantly reduced aflatoxin levels hence the need to encourage maize farmers and traders to adopt hermetic bag storage technology.This study assessed the aflatoxin contamination and the presence of fungi in three maize varieties (Obatanpa, Abontem and Aburohemaa) stored using different storage methods namely storage in hermetic bags, woven polypropylene sacks and local crib in the Nkoranza-South district of the Brong-Ahafo region of Ghana. A factorial design arrangement was laid out in a randomized complete block design (RCBD). The isolation and identification of fungal pathogens associated with maize samples before and after storage were carried out on potato dextrose agar (PDA). Total flatoxin levels in the three maize varieties was determined by the use of enzyme-linked immunosorbent assay (ELISA) at 450 nm wavelength. Six fungi species were identified in the maize namely: Aspergillus flavus, Penicillium sp, Fusarium sp., Lasiodiplodia theobromae, Colletotrichum gleosporioides and Rhizopus. Before storage, Abontem variety recorded significantly higher (p < 0.05) total aflatoxin levels (113.56 ppb) compared to Obatanpa (2.91 ppb) and Aburohemaa (2.96 ppb). Maize samples stored in the polypropylene sack established significantly higher (p < 0.05) total aflatoxin levels of 82.9 ppb compared to hermetic bags (48.9 ppb) and local crib (48.9 ppb) after storage for six months. Aflatoxin levels under the interactive effect of variety and storage method was significant (p < 0.05). Overall storage of maize in hermetic bags significantly reduced aflatoxin levels hence the need to encourage maize farmers and traders to adopt hermetic bag storage technology

Assessing roost disturbance of straw-coloured fruit bats (Eidolon helvum) through tri-axial acceleration

The disturbance of wildlife by humans is a worldwide phenomenon that contributes to the loss of biodiversity. It can impact animals' behaviour and physiology, and this can lead to changes in species distribution and richness. Wildlife disturbance has mostly been assessed through direct observation. However, advances in bio-logging provide a new range of sensors that may allow measuring disturbance of animals with high precision and remotely, and reducing the effects of human observers. We used tri-axial accelerometers to identify daytime flights of roosting straw-coloured fruit bats (Eidolon helvum), which were used as a proxy for roost disturbance. This bat species roosts on trees in large numbers (often reaching hundreds of thousands of animals), making them highly vulnerable to disturbance. We captured and tagged 46 straw-coloured fruit bats with dataloggers, containing a global positioning system (GPS) and an accelerometer, in five roosts in Ghana, Burkina Faso and Zambia. Daytime roost flights were identified from accelerometer signatures and modelled against our activity in the roosts during the days of trapping, as a predictor of roost disturbance, and natural stressors (solar irradiance, precipitation and wind speed). We found that daytime roost flight probability increased during days of trapping and with increasing solar irradiance (which may reflect the search for shade to prevent overheating). Our results validate the use of accelerometers to measure roost disturbance of straw-coloured fruit bats and suggest that these devices may be very useful in conservation monitoring programs for large fruit bat species.info:eu-repo/semantics/publishedVersio

Protected Areas in Tropical Africa: Assessing Threats and Conservation Activities

Numerous protected areas (PAs) have been created in Africa to safeguard wildlife and other natural resources. However, significant threats from anthropogenic activities and decline of wildlife populations persist, while conservation efforts in most PAs are still minimal. We assessed the impact level of the most common threats to wildlife within PAs in tropical Africa and the relationship of conservation activities with threat impact level. We collated data on 98 PAs with tropical forest cover from 15 countries across West, Central and East Africa. For this, we assembled information about local threats as well as conservation activities from published and unpublished literature, and questionnaires sent to long-term field workers. We constructed general linear models to test the significance of specific conservation activities in relation to the threat impact level. Subsistence and commercial hunting were identified as the most common direct threats to wildlife and found to be most prevalent in West and Central Africa. Agriculture and logging represented the most common indirect threats, and were most prevalent in West Africa. We found that the long-term presence of conservation activities (such as law enforcement, research and tourism) was associated with lower threat impact levels. Our results highlight deficiencies in the management effectiveness of several PAs across tropical Africa, and conclude that PA management should invest more into conservation activities with long-term duration.Additional co-authors: Jef Dupain, Atanga Ekobo, Manasseh Eno-Nku, Gilles Etoga, Takeshi Furuichi, Sylvain Gatti, Andrea Ghiurghi, Chie Hashimoto, John A. Hart, Josephine Head, Martin Hega, Ilka Herbinger, Thurston C. Hicks, Lars H. Holbech, Bas Huijbregts, Hjalmar S. Kühl, Inaoyom Imong, Stephane Le-Duc Yeno, Joshua Linder, Phil Marshall, Peter Minasoma Lero, David Morgan, Leonard Mubalama, Paul K. N'Goran, Aaron Nicholas, Stuart Nixon, Emmanuelle Normand, Leonidas Nziguyimpa, Zacharie Nzooh-Dongmo, Richard Ofori-Amanfo, Babafemi G. Ogunjemite, Charles-Albert Petre, Hugo J. Rainey, Sebastien Regnaut, Orume Robinson, Aaron Rundus, Crickette M. Sanz, David Tiku Okon, Angelique Todd, Ymke Warren, Volker Somme

Overall Dynamic Body Acceleration in Straw-Colored Fruit Bats Increases in Headwinds but Not With Airspeed

Atmospheric conditions impact how animals use the aerosphere, and birds and bats should modify their flight to minimize energetic expenditure relative to changing wind conditions. To investigate how free-ranging straw-colored fruit bats (Eidolon helvum) fly with changing wind support, we use data collected from bats fit with GPS loggers and an integrated triaxial accelerometer and measure flight speeds, wingbeat frequency, and overall dynamic body acceleration (ODBA) as an estimate for energetic expenditure. We predicted that if ODBA reflects energetic expenditure, then we should find a curvilinear relationship between ODBA and airspeed consistent with aerodynamic theory. We expected that bats would lower their airspeed with tailwind support and that ODBA will decrease with increasing tailwinds and increase with wingbeat frequency. We found that wingbeat frequency has the strongest positive relationship with ODBA. There was a small, but negative, relationship between airspeed and ODBA, and bats decreased ODBA with increasing tailwind. Bats flew at ground speeds of 9.6 ± 2.4 ms−1 (Mean ± SD, range: 4.3–23.9 ms−1) and airspeeds of 10.2 ± 2.5 ms−1, and did not modify their wingbeat frequency with speed. Free-ranging straw-colored fruit bats therefore exerted more total ODBA in headwinds but not when they changed their airspeed. It is possible that the flexibility in wingbeat kinematics may make flight of free-ranging bats less costly than currently predicted or alternatively that the combination of ODBA and airspeed at our scales of measurement does not reflect this relationship in straw-colored fruit bats. Further work is needed to understand the full potential of free-ranging bat flight and how well bio-logging techniques reflect the costs of bat flight

Understanding the effect of side groups in ionic liquids on carbon-capture properties: a combined experimental and theoretical effort

Ionic liquids are an emerging class of materials with applications in a variety of fields. Steady progress has been made in the creation of ionic liquids tailored to specific applications. However, the understanding of the underlying structure-property relationships has been slower to develop. As a step in the effort to alleviate this deficiency, the influence of side groups on ionic liquid properties has been studied through an integrated approach utilizing synthesis, experimental determination of properties, and simulation techniques. To achieve this goal, a classical force field in the framework of OPLS/Amber force fields has been developed to predict ionic liquid properties accurately. Cu(i)-catalyzed click chemistry was employed to synthesize triazolium-based ionic liquids with diverse side groups. Values of densities were predicted within 3% of experimental values, whereas self-diffusion coefficients were underestimated by about an order of magnitude though the trends were in excellent agreement, the activation energy calculated in simulation correlates well with experimental values. The predicted Henry coefficient for CO2 solubility reproduced the experimentally observed trends. This study highlights the importance of integrating experimental and computational approaches in property prediction and materials development, which is not only useful in the development of ionic liquids for CO2 capture but has application in many technological fields

The processed food revolution in African food systems and the double burden of malnutrition

African consumers have purchased increasing amounts of processed food over the past 50 years. The opportunity cost of time of women and men has increased as more of them work outside the home, driving them to buy processed food and food prepared away from home to save arduous home-processing and preparation labor. In the past several decades, this trend has accelerated with a surge on the supply side of the processing sector and small and medium enterprises (SMEs) and large private companies making massive aggregate investments. Packaged, industrialized, ultra-processed foods and sugar-sweetened beverages (SSBs) are a growing proportion of the processed food consumed. Also, in the past several decades, overweight and obesity have joined the longstanding high levels of stunting and wasting among children and extreme thinness among women of childbearing age. Together these phenomena have formed a double burden of malnutrition (DBM). The DBM has emerged as an important health problem in sub-Saharan Africa. The rise of the DBM and the increase in ultra-processed food consumption are linked. Policy makers face a dilemma. On the one hand, purchases of processed food are driven by long-term factors, such as urbanization, increased income, and employment changes, and thus policy cannot change the pursuit of convenience and labor-saving food. Moreover, much processed food, like packaged milk, is a boon to nutrition, and the processed food system is a major source of jobs for women. On the other hand, the portion (some 10–30%) of processed food that is ultra-processed is a public health challenge, and policy must address its detrimental effects on disease burden. The global experience suggests that double duty actions are most important as are selected policies focused on healthy weaning foods for addressing stunting and taxes on SSBs, nutrition labeling, and other measures can steer consumers away from unhealthy ultra-processed foods to addressing obesity and possibly child nutrition and stunting. We recommend that African governments consider these policy options, but note that the current extreme fragmentation of the processing sector, consisting of vast numbers of informal SMEs in sub-Saharan Africa, and the limited administrative/implementation capacity of many African governments require pursuing this path only gradually

A Study of Muon Neutrino Disappearance Using the Fermilab Main Injector Neutrino Beam

We report the results of a search for muon-neutrino disappearance by the Main Injector Neutrino Oscillation Search. The experiment uses two detectors separated by 734 km to observe a beam of neutrinos created by the Neutrinos at the Main Injector facility at Fermi National Accelerator Laboratory. The data were collected in the first 282 days of beam operations and correspond to an exposure of 1.27e20 protons on target. Based on measurements in the Near Detector, in the absence of neutrino oscillations we expected 336 +/- 14 muon-neutrino charged-current interactions at the Far Detector but observed 215. This deficit of events corresponds to a significance of 5.2 standard deviations. The deficit is energy dependent and is consistent with two-flavor neutrino oscillations according to delta m-squared = 2.74e-3 +0.44/-0.26e-3 eV^2 and sin^2(2 theta) > 0.87 at 68% confidence level.Comment: In submission to Phys. Rev.

Measurement of the Atmospheric Muon Charge Ratio at TeV Energies with MINOS

The 5.4 kton MINOS far detector has been taking charge-separated cosmic ray muon data since the beginning of August, 2003 at a depth of 2070 meters-water-equivalent in the Soudan Underground Laboratory, Minnesota, USA. The data with both forward and reversed magnetic field running configurations were combined to minimize systematic errors in the determination of the underground muon charge ratio. When averaged, two independent analyses find the charge ratio underground to be 1.374 +/- 0.004 (stat.) +0.012 -0.010(sys.). Using the map of the Soudan rock overburden, the muon momenta as measured underground were projected to the corresponding values at the surface in the energy range 1-7 TeV. Within this range of energies at the surface, the MINOS data are consistent with the charge ratio being energy independent at the two standard deviation level. When the MINOS results are compared with measurements at lower energies, a clear rise in the charge ratio in the energy range 0.3 -- 1.0 TeV is apparent. A qualitative model shows that the rise is consistent with an increasing contribution of kaon decays to the muon charge ratio.Comment: 16 pages, 17 figure

Measurement of neutrino velocity with the MINOS detectors and NuMI neutrino beam

The velocity of a ~3 GeV neutrino beam is measured by comparing detection times at the near and far detectors of the MINOS experiment, separated by 734 km. A total of 473 far detector neutrino events was used to measure (v-c)/c=5.12.910-5 (at 68% C.L.). By correlating the measured energies of 258 charged-current neutrino events to their arrival times at the far detector, a limit is imposed on the neutrino mass of mnu<50 MeV/c2 (99% C.L.)