The geometry of sound rays in a wind

We survey the close relationship between sound and light rays and geometry. In the case where the medium is at rest, the geometry is the classical geometry of Riemann. In the case where the medium is moving, the more general geometry known as Finsler geometry is needed. We develop these geometries ab initio, with examples, and in particular show how sound rays in a stratified atmosphere with a wind can be mapped to a problem of circles and straight lines.Comment: Popular review article to appear in Contemporary Physic

Interview: Very Rev. James W. Richardson . . . Confesses!

This interview mixes personal, spiritual, and governance questions as it asks James Richardson to reflect on the different phases of his generalate. He describes his view of himself as superior general, his approach to the office, and the way he works. He talks about his feelings and his goals. Most of the answers to the questions are short; Richardson speaks for a comparatively long time on the Daughters of Charity’s relationship to the superior general

On supergravity solutions of space-like Dp-branes

Recently the time dependent solutions of type II supergravities in $d = 10$, with the metric having the symmetry $ISO(p+1) \times SO(8-p, 1)$ have been given by two groups (Chen-Gal'tsov-Gutperle (CGG), [hep-th/0204071] and Kruczenski-Myers-Peet (KMP), [hep-th/0204144]). The supergravity solutions correspond to space-like D$p$-branes in type II string theory. While the CGG solution is a four parameter solution, the KMP solution is a three parameter solution and so in general they are different. This difference can be attributed to the fact that unlike the CGG solution, KMP uses a specific boundary condition for the metric and the dilaton field. It is shown that when we impose the boundary conditions used in the KMP solution to the CGG solution then both become three parameter solutions and they map to each other under a coordinate transformation along with a Hodge duality of the field strength. We also give the relations between the parameters characterizing the two solutions.Comment: 14 pages, LaTeX, v2: minor corrections and a reference adde

Comparison of Growth, Yield and Fruit Quality Performance of Tomatoes Varieties under Controlled Environment Condition of the Southern Guinea Savannah

Controlled agriculture environment is one of the modern techniques, which has the potential to meet the challenges faced by tomato producers in the country during the off-season. This study was conducted to evaluate the performance of five different varieties of tomatoes under controlled environment (screen house). The results revealed that the Nemoneta variety, performed better compared to other varieties in terms of plant height (8.3cm) and also have the highest shelf life of 14 days followed by Delicious with 7 days, while the number of fruits per plant was height in Small Cherry with an average of 8.733/plant, but Delicious variety gave the highest values in terms of marketable fruit weight (9.33kg) and highest pH values (4.07). In terms of fruit quality, Large Cherry variety contains the highest values for lycopene (1467.30mg/100g), vitamin A & B (56.7mg/100g & 0.62 mg/100g, respectively) and potassium (0.62%)

Addressing the Security Gap in IoT: Towards an IoT Cyber Range.

The paradigm of Internet of Things has now reached a maturity level where the pertinent research goal is the successful application of IoT technologies in systems of high technological readiness level. However, while basic aspects of IoT connectivity and networking have been well studied and adequately addressed, this has not been the case for cyber security aspects of IoT. This is nicely demonstrated by the number of IoT testbeds focusing on networking aspects and the lack of IoT testbeds focusing on security aspects. Towards addressing the existing and growing skills-shortage in IoT cyber security, we present an IoT Cyber Range (IoT-CR); an IoT testbed designed for research and training in IoT security. The IoT-CR allows the user to specify and work on customisable IoT networks, both virtual and physical, and supports the concurrent execution of multiple scenarios in a scalable way following a modular architecture. We first provide an overview of existing, state of the art IoT testbeds and cyber security related initiatives. We then present the design and architecture of the IoT Cyber Range, also detailing the corresponding RESTful APIs that help de-associate the IoT-CR tiers and obfuscate underlying complexities. The design is focused around the end-user and is based on the four design principles for Cyber Range development discussed in the introduction. Finally, we demonstrate the use of the facility via a red/blue team scenario involving a variant of man-in-the-middle attack using IoT devices. Future work includes the use of the IoT-CR by cohorts of trainees in order to evaluate the effectiveness of specific scenarios in acquiring IoT-related cyber-security knowledge and skills, as well as the IoT-CR integration with a pan-European cyber-security competence network

On the symmetries of special holonomy sigma models

In addition to superconformal symmetry, (1,1) supersymmetric two-dimensional sigma models on special holonomy manifolds have extra symmetries that are in one-to-one correspondence with the covariantly constant forms on these manifolds. The superconformal algebras extended by these symmetries close as W-algebras, i.e. they have field-dependent structure functions. It is shown that it is not possible to write down cohomological equations for potential quantum anomalies when the structure functions are field-dependent. In order to do this it is necessary to linearise the algebras by treating composite currents as generators of additional symmetries. It is shown that all cases can be linearised in a finite number of steps, except for G_2 and SU(3). Additional problems in the quantisation procedure are briefly discussed.Comment: 16 pages. Abstract improved and a few typographical errors correcte

Ocular Complications among Cases of Head Injury Seen in a Neurosurgical Hospital in Southeastern Nigeria

Background: Head injuries with ocular involvement are of great importance due to the visual morbidity and mortality which may result.Objective: To determine the pattern of ocular complications among cases of head injury seen in Memphys Hospital for Neurosurgery, Enugu, in south-eastern Nigeria.Patients and Methods: In a prospective study, consecutive patients with head injury seen in Memphys Hospital for Neurosurgery, Enugu, from June 2007 to May 2008 were analysed for age, sex, cause of head injury, presence or absence of ocular complication and type of ocular complication.Results: A total of 26 patients were analysed – 21 men and 5 women (M: F = 4:1), with an age range from 21-64 years. Road traffic accident was the leading cause of head injury, accounting for 88.3% of all the cases. All the patients presented within 72 hours of injury. Fifteen (57.7%) of the 26 patients had ocular complications in one or both eyes. The complications were more neuro-ophthalmic (76.2%) than ophthalmic (23.8%).Damage to the ocular cranial nerve was the most frequently occurring injury, accounting for 61.9% of all complications, followed by soft tissue injury, which was seen in 5 (23.8%) cases.Conclusion: Neuro-ophthalmic complications involving the ocular cranial nerves were the most commonly occurring complication among the cases of head injury seen in Memphys Hospital for Neurosurgery, Enugu.Key words: Ocular complications, head injury, Nigeria

ANOSPEX: a stochastic, spatially explicit model for studying anopheles metapopulation dynamics

Anopheles mosquitoes transmit malaria, a major public health problem among many African countries. One of the most effective methods to control malaria is by controlling the Anopheles mosquito vectors that transmit the parasites. Mathematical models have both predictive and explorative utility to investigate the pros and cons of different malaria control strategies. We have developed a C++ based, stochastic spatially explicit model (ANOSPEX; Anopheles Spatially-Explicit) to simulate Anopheles metapopulation dynamics. The model is biologically rich, parameterized by field data, and driven by field-collected weather data from Macha, Zambia. To preliminarily validate ANOSPEX, simulation results were compared to field mosquito collection data from Macha; simulated and observed dynamics were similar. The ANOSPEX model will be useful in a predictive and exploratory manner to develop, evaluate and implement traditional and novel strategies to control malaria, and for understanding the environmental forces driving Anopheles population dynamics