Physical Sciences and Mathematics Commons^™

A Review Of Baobab (Adansonia Digitata) Products: Effect Of Processing Techniques, Medicinal Properties And Uses, Donatien Kabore, Hagrétou Sawadogo-Lingani, Bréhima Diawara, Clarise Compaoré, Mamoudou H. Dicko Prof., Mogens Jacobsen

Pr. Mamoudou H. DICKO, PhD

A general literature review including the effect of processing techniques, medicinal value and uses of baobab tree is reported in this manuscript. Baobab tree has multi-purpose uses, as it produces food and non-food products such as medicines, fuel, timber, fodder. Every part of the baobab tree is reported to be useful. The seeds, leaves, roots, flowers, fruit pulp and bark of baobab are edible. Baobab leaves are used in the preparation of soup. Seeds are used as a thickening agent in soups, but they can be fermented and used as a flavouring agent or roasted and eaten as snacks. The …

New Frontiers In Ocean Exploration: The 2011 E/V Nautilus Field Season, K. Bell, R. Ballard, D. Coleman, C. Roman, M. Brennan, T. Turanli, M. Duman, S. Carey, P. Nomikou, M. Marani, M. Rosi, J. Austin, M. Canals, J. Karson, L. Mayer, Y. Makovsky

Christopher N. Roman

In the summer of 2011, the Exploration Vessel NAUTILUS is undertaking a four-month expedition to the Black, Aegean and Mediterranean Seas, and North Atlantic Ocean. The primary goal of the NAUTILUS is to create a focus of international leadership for the development and integration of leading-edge technologies, educational programs, field operations, and public outreach programs for ocean exploration, in partnership with NOAA, National Geographic Society, Office of Naval Research, and other sponsors. To do so, the program uses a complement of deep submergence vehicle systems and “telepresence” technologies to engage scientists, educators and the public, both at sea and ashore, …

High Resolution Sea Floor Bathymetry Using High Frequency Multibeam Sonar And Structured Light Laser Imaging, C. Roman, G. Inglis, C. Smart, I. Vaughn, S. Carey

Christopher N. Roman

Detailed bathymetric maps of the sea floor with centimeter level resolution can be produced by underwater vehicles using multibeam sonars and structured light laser imaging. Over spatial scales up to tens of thousands of square meters it is possible to produce maps gridded to sub centimeter levels. This level of accuracy demands detailed treatments of the sensor relative data, the vehicle navigation data and the vehicle to sensor position and rotational offsets. The presented results will show comparisons between these two sensor modalities. Data have a been collected during recent field programs to the Kolumbo volcanic crater and the Southern …

Remote Analysis Of Grain Size Characteristic In Submarine Pyroclastic Deposits From Kolumbo Volcano, Greece, C. Smart, D. P. Whitesell, C. Roman, S. Carey

Christopher N. Roman

Grain size characteristics of pyroclastic deposits provide valuable information about source eruption energetics and depositional processes. Maximum size and sorting are often used to discriminate between fallout and sediment gravity flow processes during explosive eruptions. In the submarine environment the collection of such data in thick pyroclastic sequences is extremely challenging and potentially time consuming. A method has been developed to extract grain size information from stereo images collected by a remotely operated vehicle (ROV). In the summer of 2010 the ROV Hercules collected a suite of stereo images from a thick pumice sequence in the caldera walls of Kolumbo …

Detection Of Diffuse Sea Floor Venting Using Structured Light Imaging, G. Inglis, C. Smart, C. Roman, S. Carey

Christopher N. Roman

Efficiently identifying and localizing diffuse sea floor venting at hydrothermal and cold seep sites is often difficult. Actively venting fluids are usually identified by a temperature induced optical shimmering seen during direct visual inspections or in video data collected by vehicles working close to the sea floor. Relying on such direct methods complicates establishing spatial relations between areas within a survey covering a broad area. Our recent work with a structured light laser system has shown that venting can also be detected in the image data in an automated fashion. A structured light laser system consists of a camera and …

Pandaa: Physical Arrangement Detection Of Networked Devices Through Ambient-Sound Awareness, Zheng Sun, Aveek Purohit, Kaifei Chen, Shijia Pan, Trevor Pering, Pei Zhang

Zheng Sun

Future ubiquitous home environments can contain 10s or 100s of devices. Ubiquitous services running on these devices (i.e. localizing users, routing, security algorithms) will commonly require an accurate location of each device. In order to obtain these locations, existing techniques require either a manual survey, active sound sources, or estimation using wireless radios. These techniques, however, need additional hardware capabilities and are intrusive to the user. Non-intrusive, automatic localization of ubiquitous computing devices in the home has the potential to greatly facilitate device deployments.

This paper presents the PANDAA system, a zero-configuration spatial localization system for networked devices based on …

Pandaa: Physical Arrangement Detection Of Networked Devices Through Ambient-Sound Awareness, Zheng Sun, Aveek Purohit, Kaifei Chen, Shijia Pan, Trevor Pering, Pei Zhang

Aveek Purohit

Future ubiquitous home environments can contain 10s or 100s of devices. Ubiquitous services running on these devices (i.e. localizing users, routing, security algorithms) will commonly require an accurate location of each device. In order to obtain these locations, existing techniques require either a manual survey, active sound sources, or estimation using wireless radios. These techniques, however, need additional hardware capabilities and are intrusive to the user. Non-intrusive, automatic localization of ubiquitous computing devices in the home has the potential to greatly facilitate device deployments.

This paper presents the PANDAA system, a zero-configuration spatial localization system for networked devices based on …

Pandaa: A Physical Arrangement Detection Technique For Networked Devices Through Ambient-Sound Awareness, Zheng Sun, Aveek Purohit, Philippe De Wagter, Irina Brinster, Chorom Hamm, Pei Zhang

Zheng Sun

This demo presents PANDAA, a zero-configuration automatic spatial localization technique for networked devices based on ambient sound sensing. We will demonstrate that after initial placement of the devices, ambient sounds, such as human speech, music, footsteps, finger snaps, hand claps, or coughs and sneezes, can be used to autonomously resolve the spatial relative arrangement of devices, such as mobile phones, using trigonometric bounds and successive approximation.

Vuv Absorption Cross Section Of Benzene, Relevance For Titan’S Atmosphere, F-J. Capalbo, Y. Bénilan, N. Fray, M. Schwell, Et. Es-Sebbar, N. Champion, T. Koskinen, R. Yelle

Dr. Et-touhami Es-sebbar

Saturn's largest satellite, Titan, is the only one in the Solar System known to have a thick N2/CH4, planet like atmosphere. The dissociation of these principal components and the recombination of the products make this atmosphere to be rich in organic compounds of high interest for astrobiology. Solar and stellar occultations observed by the Ultraviolet Imaging Spectrograph (UVIS) on board the Cassini spacecraft can be used to characterize the composition of Titan’s upper atmosphere (400 – 1400 km). The results depend strongly on the knowledge of the molecular absorption cross sections of the atmospheric constituents (Ferradaz et al. 2009). This …

Bistability In A Simple Fluid Network Due To Viscosity Contrast, John B. Geddes, Brian D. Storey, David Gardner, Russell T. Carr

John B. Geddes

We study the existence of multiple equilibrium states in a simple fluid network using Newtonian fluids and laminar flow. We demonstrate theoretically the presence of hysteresis and bistability, and we confirm these predictions in an experiment using two miscible fluids of different viscosity—sucrose solution and water. Possible applications include blood flow, microfluidics, and other network flows governed by similar principles.

Coughloc: Location-Aware Indoor Acoustic Sensing For Non-Intrusive Cough Detection, Zheng Sun, Aveek Purohit, Kathleen Yang, Neha Pattan, Dan Siewiorek, Asim Smailagic, Ian Lane, Pei Zhang

Zheng Sun

Pervasive medical monitoring has become an ideal alter- native to nursing care for elderly people and patients in hospitals. Existing systems using single body-worn sensors are often intrusive and less reliable. By contrast, ubiqui- tous acoustic sensing techniques can support non-intrusive and robust medical monitoring. In this paper, we describe CoughLoc, a ubiquitous acoustic sensing system for con- tinuous cough detection using a wireless sensor network. We show how knowledge of sound source locations can be leveraged to improve the detection accuracy of sound events caused by mobile users. Experiments in indoor environ- ments show our system achieves over 90% …

Antimicrobial And Antioxidant Activities Of Essential Oil And Methanol Extract Of Matricaria Chamomilla L. From Djibouti, Fatouma M. Abdoul-Latif, Mohamed Nabil, Prosper Edou, Adwa A. Ali, Samatar O. Djama, Louis-Clément Obamé, Mamoudou H. Dicko Prof.

Pr. Mamoudou H. DICKO, PhD

The essential oil and methanol extracts of Matricaria Chamomilla L. were subjected to screening for their possible antioxidant activity by two complementary test systems, namely 2,2-diphenykpicrylhydrazyl (DPPH) free radical scavenging and β-carotene-linoleic acid assays. BHT was used as positive control in both test systems. In the DPPH test system, the IC50 values of essential oil and methanol extracts were 4.18 and 1.83 μg/ml, respectively. In the β-carotene-linoleic acid system, oxidation was effectively inhibited by M. Chamomilla, the RAA value of essential oil and methanol extracts were 12.69 and 11.37 %, respectively. When compared to BHT, the essential oil and methanol …

Coughloc: Location-Aware Indoor Acoustic Sensing For Non-Intrusive Cough Detection, Zheng Sun, Aveek Purohit, Kathleen Yang, Neha Pattan, Dan Siewiorek, Asim Smailagic, Ian Lane, Pei Zhang

Aveek Purohit

Pervasive medical monitoring has become an ideal alter- native to nursing care for elderly people and patients in hospitals. Existing systems using single body-worn sensors are often intrusive and less reliable. By contrast, ubiqui- tous acoustic sensing techniques can support non-intrusive and robust medical monitoring. In this paper, we describe CoughLoc, a ubiquitous acoustic sensing system for con- tinuous cough detection using a wireless sensor network. We show how knowledge of sound source locations can be leveraged to improve the detection accuracy of sound events caused by mobile users. Experiments in indoor environ- ments show our system achieves over 90% …

Development Of High Resolution Sea Floor Mapping Tools And Techniques, Gabrielle Inglis, Ian Vaughn, Clara Smart, Chris Roman

Christopher N. Roman

There is a persistent need for high resolution photographic and bathymetric maps of the sea floor for many research areas in marine geology, biology and archaeology. This poster will present recent work using high frequency multibeam sonars, stereo vision and structured light laser imaging techniques to create maps with centimeter resolution for these applications. This research involves the development of new image and sonar processing techniques that combat the typical difficulties of imperfect navigation information, limited sensor ranges and adverse environmental conditions associated with using marine robotic vehicles in the ocean. Data for this work has been collected with the …

Sensorfly: Controlled-Mobile Sensing Platform For Indoor Emergency Response Applications, Aveek Purohit, Zheng Sun, Frank Mokaya, Pei Zhang

Aveek Purohit

Indoor emergency response situations, such as urban fire, are characterized by dangerous constantly-changing operating environments with little access to situational information for first responders. In-situ information about the conditions, such as the extent and evolution of an indoor fire, can augment rescue efforts and reduce risk to emergency personnel. Static sensor networks that are pre-deployed or manually deployed have been proposed, but are less practical due to need for large infrastructure, lack of adaptivity and limited coverage. Controlled-mobility in sensor networks, i.e. the capability of nodes to move as per network needs can provide the desired autonomy to overcome these …

Sensorfly: Controlled-Mobile Sensing Platform For Indoor Emergency Response Applications, Aveek Purohit, Zheng Sun, Frank Mokaya, Pei Zhang

Zheng Sun

Indoor emergency response situations, such as urban fire, are characterized by dangerous constantly-changing operating environments with little access to situational information for first responders. In-situ information about the conditions, such as the extent and evolution of an indoor fire, can augment rescue efforts and reduce risk to emergency personnel. Static sensor networks that are pre-deployed or manually deployed have been proposed, but are less practical due to need for large infrastructure, lack of adaptivity and limited coverage. Controlled-mobility in sensor networks, i.e. the capability of nodes to move as per network needs can provide the desired autonomy to overcome these …

Characterization Of Continuous Vacuum Ultraviolet Lamps-Implication On The Study Of Methane Photolysis At Lyman Alpha (121.6 Nm), M-C. Gazeau, Y. Benilan, Et. Es-Sebbar, A. Jolly, E. Arzoumanian, N. Fray, H. Cottin

Dr. Et-touhami Es-sebbar

Low-temperature hydrogen plasmas are widely used as continuous vacuum ultraviolet irradiation sources in photochemical studies and, in particular, in laboratory simulations of planetary atmospheres. One of the most challenging objectives of such experiments is to retrieve accurate quantitative laboratory data allowing a reliable comparison with theoretical and/or observational ones. This task can only be achieved when the irradiation source delivers a well characterised radiation in terms of flux and wavelength dependency. As an example, we will present a study, developed in the frame of a program dedicated to simulations of Titan’s atmosphere, on methane photolysis at Lyman alpha (121.6 nm). …

Formation Of Hcn And Nh3 As Primary Compounds Of Titan’S Atmosphere Simulations Using N2-Ch4 Afterglow Plasma’’, M-C. Gazeau, Y. Bénilan, E. Arzoumanian, Et. Es-Sebbar, A. Jolly, C.D. Pintassilgo

Dr. Et-touhami Es-sebbar

No abstract provided.

Argon Rectification And The Cause Of Light Emission In Single-Bubble Sonoluminescence, Brian D. Storey, Andrew J. Szeri

Brian Storey

In single-bubble sonoluminescence, repeated brief flashes of light are produced in a gas bubble strongly driven by a periodic acoustic field. A startling hypothesis has been made by Lohse and co-workers [Phys. Rev. Lett. 78, 1359 (1997)] that the non-noble gases in an air bubble undergo chemical reaction into soluble products, leaving only argon. In the present work, this dissociation hypothesis is supported by simulations, although the associated temperatures of about 7000 K seem too low for bremsstrahlung, which has been proposed as the dominant light emission mechanism. This suggests that emission from water vapor and its reaction products, heretofore …

Shape Stability Of Sonoluminescence Bubbles: Comparison Of Theory To Experiments, Brian D. Storey

Brian Storey

Single bubble sonoluminescence (SBSL) is the brief flash of light emitted from a single, stable, acoustically forced bubble. In experiments, the maximum pressure amplitude with which a bubble may be forced is limited by considerations of spherical stability. The traditional linear stability analysis predicts a threshold for SBSL at a much lower pressure amplitude than experimental observations. This work shows that if one constructs an accurate model of the radial dynamics, the traditional linear stability analysis predicts a boundary that is in excellent agreement with experimental data.

Field-Amplified Sample Stacking And Focusing In Nanofluidic Channels, Jess M. Sustarich, Brian D. Storey, Sumita Pennathur

Brian Storey

Nanofluidic technology is gaining popularity for bioanalytical applications due to advances in both nanofabrication and design. One major obstacle in the widespread adoption of such technology for bioanalytical systems is efficient detection of samples due to the inherently low analyte concentrations present in such systems. This problem is exacerbated by the push for electronic detection, which requires an even higher sensor-local sample concentration than optical detection. This paper explores one of the most common preconcentration techniques, field-amplified sample stacking, in nanofluidic systems in efforts to alleviate this obstacle. Holding the ratio of background electrolyte concentrations constant, the parameters of channel …

Rayleigh-Taylor Instability Of Violently Collapsing Bubbles, Hao Lin, Brian D. Storey, Andrew J. Szeri

Brian Storey

In a classical paper Plesset has determined conditions under which a bubble changing in volume maintains a spherical shape. The stability analysis was further developed by Prosperetti to include the effects of liquid viscosity on the evolving shape modes. In the present work the theory is further modified to include the changing density of the bubble contents. The latter is found to be important in violent collapses where the densities of the gas and vapor within a bubble may approach densities of the liquid outside. This exerts a stabilizing influence on the Rayleigh–Taylor mechanism of shape instability of spherical bubbles. …

Electrohydrodynamic Instabilities In Microchannels With Time Periodic Forcing, David A. Boy, Brian D. Storey

Brian Storey

In microfluidic applications it has been observed that flows with spatial gradients in electrical conductivity are unstable under the application of sufficiently strong electric fields. These electrohydrodynamic instabilities can drive a nonlinear flow despite the low Reynolds number. Such flows hold promise as a simple mechanism for mixing fluids. In this work, the effect of a time periodic electric field on the instability is explored. The case where an electric field is applied across a diffuse interface of two fluids with varying electrical conductivity is considered. Frequency-dependent behavior is found only in the regime where the instability growth rates are …

Bistability In A Simple Fluid Network Due To Viscosity Contrast, John B. Geddes, Brian D. Storey, David Gardner, Russell T. Carr

Brian Storey

We study the existence of multiple equilibrium states in a simple fluid network using Newtonian fluids and laminar flow. We demonstrate theoretically the presence of hysteresis and bistability, and we confirm these predictions in an experiment using two miscible fluids of different viscosity—sucrose solution and water. Possible applications include blood flow, microfluidics, and other network flows governed by similar principles.

Bulk Electroconvective Instability At High Péclet Numbers, Brian D. Storey, Boris Zaltzman, Isaak Rubinstein

Brian Storey

Bulk electroconvection pertains to flow induced by the action of a mean electric field upon the residual space charge in the macroscopic regions of a locally quasielectroneutral strong electrolyte. For a long time, controversy has existed in the literature as to whether quiescent electric conduction from such an electrolyte into a uniform charge-selective solid, such as a metal electrode or ion exchange membrane, is stable with respect to bulk electroconvection. While it was recently claimed that bulk electroconvective instability could not occur, this claim pertained to an aqueous, low-molecular-weight electrolyte characterized by an order-unity electroconvection Péclet number. In this paper, …

Instability Of Electro-Osmotic Channel Flow With Streamwise Conductivity Gradients, J. Jobim Santos, Brian D. Storey

Brian Storey

This work considers the stability of an electro-osmotic microchannel flow with streamwise electrical conductivity gradients, a configuration common in microfluidic applications such as field amplified sample stacking. Previous work on such flows has focused on how streamwise conductivity gradients set a nonuniform electro-osmotic velocity which results in dispersion of the conductivity field. However, it has been known for many years that electric fields can couple with conductivity gradients to generate unstable flows. This work demonstrates that at high electric fields such an electrohydrodynamic instability arises in this configuration and the basic mechanisms are explored through numerical simulations. The instability is …

Steric Effects On Ac Electro-Osmosis In Dilute Electrolytes, Brian D. Storey, Lee R. Edwards, Mustafa Sabri Kilic, Martin Z. Bazant

Brian Storey

The current theory of alternating-current electro-osmosis (ACEO) is unable to explain the experimentally observed flow reversal of planar ACEO pumps at high frequency (above the peak, typically 10–100 kHz), low salt concentration (1–1000 μM), and moderate voltage (2–6 V), even taking into account Faradaic surface reactions, nonlinear double-layer capacitance, and bulk electrothermal flows. We attribute this failure to the breakdown of the classical Poisson-Boltzmann model of the diffuse double layer, which assumes a dilute solution of pointlike ions. In spite of low bulk salt concentration, the large voltage induced across the double layer leads to crowding of the ions and …

A Depth-Averaged Electrokinetic Flow Model For Shallow Microchannels, Hao Lin, Brian D. Storey, Juan G. Santiago

Brian Storey

Electrokinetic flows with heterogeneous conductivity configuration occur widely in microfluidic applications such as sample stacking and multidimensional assays. Electromechanical coupling in these flows may lead to complex flow phenomena, such as sample dispersion due to electro-osmotic velocity mismatch, and electrokinetic instability (EKI). In this work we develop a generalized electrokinetic model suitable for the study of microchannel flows with conductivity gradients and shallow-channel geometry. An asymptotic analysis is performed with the channel depth-to-width ratio as a smallness parameter, and the three-dimensional equations are reduced to a set of depth-averaged equations governing in-plane flow dynamics. The momentum equation uses a Darcy–Brinkman–Forchheimer-type …

Cortina: Collaborative Context-Aware Indoor Positioning Employing Rss And Rtof Techniques, Zheng Sun, Richard Farley, Telis Kaleas, Judy Ellis, Kiran Chikkappa

Zheng Sun

Cortina is an energy-efficient indoor localization system, which leverages a wireless sensor network to support navigation and tracking applications. To improve the localization performance, we develop a hybrid ranging system, which incor- porate both RSS and RToF-based techniques. To overcome effects from indoor multipath, we design and implement algorithms to take account various context information. We evaluated the system over a 2000m2 area instrumented with twenty-six fixed nodes. Evaluation results show the system achieved 2.5m accuracy in a pedestrian tracking application.

Biodepollution Of Wastewater Containing Phenolic Compounds From Leather Industry By Plant Peroxidases, Mamounata Diao, Nafissetou Ouedraogo, Lamine Baba-Moussa, Paul W. Savadogo, Georges N'Guessan Amani, Mamoudou H. Dicko Prof.

Pr. Mamoudou H. DICKO, PhD

This study deals with the use of peroxidases (POXs) from Allium sativum, Ipomoea batatas, Raphanus sativus and Sorghum bicolor to catalyze the degradation of free phenolic compounds as well as phenolic compounds contained in wastewater from leather industry. Secretory plant POXs were able to catalyze the oxidation of gallic acid, ferulic acid, 4-hydroxybenzoic acid, pyrogallol and 1,4-tyrosol prepared in ethanol 2% (v:v). Efficiency of peroxidase catalysis depends strongly on the chemical nature of phenolic substrates and on the botanical source of the enzymes. It appeared that POX from Raphanus sativus had the highest efficiency. Results show that POXs can also …