Observable Neutron-Antineutron Oscillations in Seesaw Models of Neutrino Mass

We show that in a large class of supersymmetric models with spontaneously broken B-L symmetry, neutron--antineutron oscillations occur at an observable level even though the scale of B-L breaking is very high, v_{B-L} ~ 2 x 10^{16} GeV, as suggested by gauge coupling unification and neutrino masses. We illustrate this phenomenon in the context of a recently proposed class of seesaw models that solves the strong CP problem and the SUSY phase problem using parity symmetry. We obtain an upper limit on N-\bar{N} oscillation time in these models, \tau_{N-\bar{N}} < 10^{9} -10^{10} sec. This suggests that a modest improvement in the current limit on \tau_{N-\bar{N}} of 0.86 x 10^8 sec will either lead to the discovery of N-\bar{N} oscillations, or will considerably restrict the allowed parameter space of an interesting class of neutrino mass models.Comment: 11 pages RevTeX, 1 figur

Linking Mara Fruits and Vegetable Growers to Serengeti National Park Tourist Hotels Market

Tourism in Tanzania has been on the rise since late 1990s when the markets were fully liberalized. This has created a high demand for horticultural produces from tourist hotels located in Serengeti national park in the northwest of Tanzania. Analysis was carried out to determine supply and demand for horticultural produces in Mara region. The annual requirements for horticulture produces in three Serengeti tourist hotels were about 614 tons. These hotels obtain most of the fruits and vegetables from Arusha, Kenya and South Africa which are very far from the park. Due to long distances and poor roads the hotels obtain high priced, low quality and small quantities of produces. The production of horticulture in Mara region is about 620 tons which is more than what is demanded by the hotels. The major problems hindering horticulture production in Mara region include unstable markets, erratic prices and low demand for horticulture produces. The tourist hotels demand locally produced, regular supply, fresh and medium quality horticulture produces while farmers want regular markets for their produces. The Gross Margin analysis indicated that supplier gross profit and growers’ return to labour are high with horticultural crops as compared to other crops. The study recommends that the hotels and growers establish contract agreement to enhance reliable deliveries. To improve production and entrepreneurial skills of the farmers; management support at the beginning of implementation from extension, research, credit and irrigation schemes from local institutions would be necessary. Keywords: Mara Fruits, Tourism, Serengeti, TanzaniaAgricultural and Food Policy, Community/Rural/Urban Development, Farm Management, Food Consumption/Nutrition/Food Safety, Food Security and Poverty, International Relations/Trade, Marketing, Productivity Analysis, Research and Development/Tech Change/Emerging Technologies,

Near Tribimaximal Neutrino Mixing with Delta(27) Symmetry

The discrete subgroup Delta(27) of SU(3) has the interesting multiplication rule 3 X 3 = bar{3} + bar{3} + bar{3}, which is used to obtain near tribimaximal neutrino mixing. Using present neutrino oscillation data as input, this model predicts that the effective mass m_{ee} measured in neutrinoless double beta decay will be 0.14 eV.Comment: 6 pages, no figur

Fluorescence energy transfer enhancement in aluminum nanoapertures

Zero-mode waveguides (ZMWs) are confining light into attoliter volumes, enabling single molecule fluorescence experiments at physiological micromolar concentrations. Among the fluorescence spectroscopy techniques that can be enhanced by ZMWs, F\"{o}rster resonance energy transfer (FRET) is one of the most widely used in life sciences. Combining zero-mode waveguides with FRET provides new opportunities to investigate biochemical structures or follow interaction dynamics at micromolar concentration with single molecule resolution. However, prior to any quantitative FRET analysis on biological samples, it is crucial to establish first the influence of the ZMW on the FRET process. Here, we quantify the FRET rates and efficiencies between individual donor-acceptor fluorophore pairs diffusing in aluminum zero-mode waveguides. Aluminum ZMWs are important structures thanks to their commercial availability and the large literature describing their use for single molecule fluorescence spectroscopy. We also compare the results between ZMWs milled in gold and aluminum, and find that while gold has a stronger influence on the decay rates, the lower losses of aluminum in the green spectral region provide larger fluorescence brightness enhancement factors. For both aluminum and gold ZMWs, we observe that the FRET rate scales linearly with the isolated donor decay rate and the local density of optical states (LDOS). Detailed information about FRET in ZMWs unlocks their application as new devices for enhanced single molecule FRET at physiological concentrations

Nanophotonic enhancement of the F\"orster resonance energy transfer rate on single DNA molecules

Nanophotonics achieves accurate control over the luminescence properties of a single quantum emitter by tailoring the light-matter interaction at the nanoscale and modifying the local density of optical states (LDOS). This paradigm could also benefit to F\"orster resonance energy transfer (FRET) by enhancing the near-field electromagnetic interaction between two fluorescent emitters. Despite the wide applications of FRET in nanosciences, using nanophotonics to enhance FRET remains a debated and complex challenge. Here, we demonstrate enhanced energy transfer within single donor-acceptor fluorophore pairs confined in gold nanoapertures. Experiments monitoring both the donor and the acceptor emission photodynamics at the single molecule level clearly establish a linear dependence of the FRET rate on the LDOS in nanoapertures. These findings are applied to enhance the FRET rate in nanoapertures up to six times, demonstrating that nanophotonics can be used to intensify the near-field energy transfer and improve the biophotonic applications of FRET

Enhancement of biogas potential of primary sludge by co-digestion with cow manure and brewery sludge

Anaerobic digestion (AD) has long been used to treat different types of organic wastes especially in the developed world. However, organic wastes are still more often considered as a waste instead of a resource in the developing world, which contributes to environmental pollution arising from their disposal. This study has been conducted at Bugolobi Sewage Treatment Plant (BSTP), where two organic wastes, cow manure and brewery sludge were co-digested with primary sludge in different proportions. This study was done in lab-scale reactors at mesophilic temperature and sludge retention time of 20 d. The main objective was to evaluate the biodegradability of primary sludge generated at BSTP, Kampala, Uganda and enhance its ability of biogas production. When the brewery sludge was added to primary STP sludge at all proportions, the biogas production rate increased by a factor of 3. This was significantly (p<0.001) higher than observed gas yield (337 +/- 18 mL/(L.d)) in the control treatment containing (only STP sludge). Co-digesting STP sludge with cow manure did not show different results compared to the control treatment. In conclusion, Bugolobi STP sludge is poorly anaerobically degradable with low biogas production but co-digestion with brewery sludge enhanced the biogas production rate, while co-digestion with cow manure was not beneficial

Efficacious Additions to the Standard Model

If split supersymmetry can be advocated as a means to have gauge-coupling unification as well as dark matter, another plausible scenario is to enlarge judiciously the particle content of the Standard Model to achieve the same goals without supersymmetry. A simple efficacious example is presented.Comment: 6 pages, no figure, one reference added, version to appear in PL

A Maximal Atmospheric Mixing from a Maximal CP Violating Phase

We point out an elegant mechanism to predict a maximal atmospheric angle, which is based on a maximal CP violating phase difference between second and third lepton families in the flavour symmetry basis. In this framework, a discussion of the predictions for theta_{12}, |U_{e3}|, delta and their possible correlations is provided. We also present an explicit realisation in terms of an SO(3) flavour symmetry model.Comment: v2=published version: 11 pages, 4 figures, text improved, reference adde

Plasmonic antennas and zero mode waveguides to enhance single molecule fluorescence detection and fluorescence correlation spectroscopy towards physiological concentrations

Single-molecule approaches to biology offer a powerful new vision to elucidate the mechanisms that underpin the functioning of living cells. However, conventional optical single molecule spectroscopy techniques such as F\"orster fluorescence resonance energy transfer (FRET) or fluorescence correlation spectroscopy (FCS) are limited by diffraction to the nanomolar concentration range, far below the physiological micromolar concentration range where most biological reaction occur. To breach the diffraction limit, zero mode waveguides and plasmonic antennas exploit the surface plasmon resonances to confine and enhance light down to the nanometre scale. The ability of plasmonics to achieve extreme light concentration unlocks an enormous potential to enhance fluorescence detection, FRET and FCS. Single molecule spectroscopy techniques greatly benefit from zero mode waveguides and plasmonic antennas to enter a new dimension of molecular concentration reaching physiological conditions. The application of nano-optics to biological problems with FRET and FCS is an emerging and exciting field, and is promising to reveal new insights on biological functions and dynamics.Comment: WIREs Nanomed Nanobiotechnol 201

Triplicity of Quarks and Leptons

Quarks come in three colors and have electric charges in multiples of one-third. There are also three families of quarks and leptons. Whereas the first two properties can be understood in terms of unification symmetries such as SU(5), SO(10), or E_6, why there should only be three families remains a mystery. I propose how all three properties involving the number three are connected in a fivefold application of the gauge symmetry SU(3).Comment: 10 pages, including 2 figure