Recent Submissions

  • Characterization of New Cell Factory Candidate for Saudi Arabia Application

    Mei Ng, Yi; Azlin Mokhtar, Noor; Ahmad Jamhor ,Suhaiza; Archer ,John (2019-01-13) [Poster]
    Characterization of a New Cyanobacterial Cell Factory Strain for Saudi Arabia Application The use of photosynthetic cells as platform for bio-manufacturing is gaining increasing interest as it promises todeliver a sustainable, carbon neutral production system for biomass-derived chemicals, fuels and foods. SaudiArabia, in particular, is an excellent place for the deployment of photosynthetic cell factory as algal biotechnologyleverages the country’s abundant sunlight, availability of large CO2 point source emissions and access to Red Seaand Gulf waters (38 – 40 PSU). Currently a few model picocyanobacterial strain have been extensively studied forbiofuel and biochemical production, but these strains are limited to mild temperature, light and salinity conditionsthus cannot operate under Saudi Arabian climate. Therefore, in order to develop cyanobacterial cell factoryapplications for the Arabian Peninsula, there is a pressing need to discover and develop strains that can thriveunder extremely warm temperatures, high insolation and high salinity. In our study, a native unicellularSynechococcus sp. RSCCF101 strain isolated from the central Red Sea has been identified as a potential cellfactory candidate. Here we present physiological and genomic characterization of Synechococcus sp. RSCCF101to support its development as a new robust marine cell factory strain. Summary •Strain RSCCF101 is a candidate marine cyanobacterial cell factory strain isolated from the central Red Sea. It has an ovoid structure of about 1 µm length and 0.8 µm diameter (Figure 1) and 16S rRNA phylogenetic tree analysis places RSCCF101 within the Synechoccocus cluster (Figure 2). •The physiological profile showed that Synechococcus sp. RSCCF101 is both thermo- and halotolerant where it is able to grow efficiently at temperature up to 38°C and salinity between 10 PSU and 40 PSU, while remained viable at 50 PSU and 60 PSU (Figure 3A and 3B). These are desirable characteristics of a cell factory candidate as the chassis strain has to be able to survive the warm climate and intense insolation in Saudi Arabia (Nielsen, Archer et al. 2017). •Synechococcus sp. RSCCF101 is capable of producing high amount of phycocyanin under low light condition and glycogen under high light condition (Figure 4A to 4D). Phycocyanin is a valuable product for bioassay, bioimaging, pharmaceutical, food and cosmetics industry application (Chakdar and Pabbi 2016) while glycogen can be used as biofuel feedstock (Aikawa, Nishida et al. 2014). •Whole genome was successfully constructed for Synechococcus sp. RSCCF101 (Figure 5), from which a complete gene set involving in glycogen biosynthesis was identified (Figure 6). In addition, the genome contains three sets of cpcBA which encodes the alpha and beta subunits of phycocyanin (Figure 7). •Future work will include a more detailed genomic and transcriptomic profiling of RSCCF101 to establish the understanding of the physiological and molecular traits for synthetic biology purposes.
  • Synthesis of Red-Shifted Flourescent Voltage Sensors

    Deal, Parker; Al Abdullatif, Sarah; Miller, Evan (2019-01-13) [Poster]
    Synthesis of Red-Shifted Flourescent Voltage Sensors Sarah Al Abdullatif; Parker Deal; Prof. Evan Miller UC Berkeley, Department of Chemistry Introduction Fluorescence imaging can be used to monitor electrical activity in neurons by using voltage sensitive dyes (VSDs). VSDs allow the measurement of transmembrane potentials through a photo-induced electron transfer (PeT) from an electron donor through a molecular wire to a uorophore. At resting or hyperpolarized potentials, the transmembrane electric eld promotes PeT, quenching the excited-state uorophore. Depolarization reverses the electric eld, decreasing the rate of PeT, and therefore leading to an increase of uorescence. Recently we reported the development of a new class of VFs based on isomerically pure tetramethylrhodamines. These new Rhodamine Voltage Reporters, or RhoVRs, use photoinduced electron transfer (PeT) as a trigger for voltage sensing to measure changes in membrane potential with high sensitivity (up to 47% F/F per 100 mV). In addition, RhoVRs possess excitation and emission proles in the green to orange region of the visible spectrum, allowing for use alongside commonly used green uorescent tools such as GFP. Modications to RhoVR Piperazine Functionalized Voltage Reporters Functionalization of RhoVR dyes with L-cysteic acid functionalized piperazine maintains a tertiary amide at the 2’ position, includes a sulfonate to aid with solubility and orientation of the dye in the membrane , and provides a nucleophilic handle for attachment of targeting ligands. In addition to modications at the 2' position, a new RhoVR, RhoVR(Me), was synthesized with a less electron rich wire that is complementary dye to RhoVR(OMe) as it is much brighter, however less sensitive, than the parent VF. Genetic Targeting Using HaloTag RhoVRs have demonstrated the ability to record neuronal activity with good signal to noise ratio, however the dyes indiscriminately label all membranes, leading to high levels of background uorescence. We have chosen to utilize HaloTag® technology as a means to address the limitations of RhoVRs through genetic targeting. HaloTag® is a dehalogenase-based labeling system which forms a covalent linkage between a protein tag and a chemical ligand (chloroalkane). By expressing Halotag extracellularly, then adding RhoVR linked to the HaloTag® ligand via a exible linker (PEG), we hope to gain the selectivity of genetically encoded voltage indicators (GEVIs) while maintaining the favorable photophysical properties of the small-molecule VF. PEG linkers of varying length were also investigated to determine if linker length aected the voltage sensitivity of the dyes. Genetic Targeting and Voltage Sensitivity The voltage sensitivites of the RhoVR-PEGn-Halo compounds were determined using patch-clamp electrophysiology. All derivatives were capable of measuring membrane potential, but also showed attenuated voltage sensitivities from the parent sarcosine-functionalized compounds. In addition the RhoVR-PEGn-HaloTag® compounds were roughly one third as bright as the parent dyes. Future Work Future work with RhoVR-PEG-Halos will aim to both improve upon the photophysical properties of the targeted voltage dyes as well as exploring the biological scope of HaloTag® system. Specically, this will include: 1) Further investigating the relationship between linker design and voltage sensitivity 2) Employing far-red voltage dyes to improve SNR and photostability 3) Genetic targeting of neuronal sub-types (excitatory, inhibitory) and sub-cellular domains (pre synaptic, post-synaptic) 4) Utilization of the RhoVR-PEG-Halos in more intact preparations (i.e. brain slice) 5) Development of a HaloTag®/GCaMP6s construct to enable simultaneous Ca2+ and voltage imaging
  • One step genome-wide association study of traits contributing to salinity stress in rice grown under controlled and field conditions

    Al-Tamimi, Nadia; Oakey, Helena; Garcia, Garcia; Berger, Bettina; Brien, Chris; Mbodj, Daouda; Manneh, Baboucarr; Tester, Mark; Negrao ,Sonia (2019-01-13) [Poster]
    One step genome-wide association study of traits contributing to salinity stress in rice grown under controlled and field conditions Background •Rice is the staple crop that feeds more than half of the world 1 •It is the most salt-sensitive cereal 2 •We need to use land that is currently unsuitable for rice production (e.g. by use of salt-tolerant rice varieties) to help address global food security •Salinity tolerance in plants is a complex quantitative trait that has various components àdissected effectively using single step GWAS models.
  • Micro Drug Delivery System for Heart Disease

    Moussi, Khalil; Kosel, Jurgen (2019-01-13) [Poster]
    1. INTRODUCTION & MOTIVATION Ø For the last decades, Coronary Artery Disease (CAD) has been the deadliest disease in the world. Ø CAD caused 8.76 million deaths in the year 2017 according to the World Health Organization (WHO). Ø In Saudi Arabia: • CAD is the leading cause of death in the year 2016, • The number of death had a 20% increase from the year 2005 to 2016 according to WHO. Ø Existing interventions and drawbacks: • Angioplasty: - Re-narrowing of the artery within the stent - Blood clot formation - Compressed plaque - Re-narrowing in the surrounding of the stent • Coronary Artery Bypass Grafting (CABG): - Long surgery (6 - 8 hours) under general anesthetic - Risk of bleeding from the grafting area - Heart rhythm problems and blood clots which higher the risk of stroke To definitively eradicate the disease, a new treatment technique is required. 2. DESIGN & CONCEPT Ø A micro drug delivery system consisting of an electrolytic pump and drug reservoir with micro-needles is attached to a balloon catheter that pushes the micro-needles into the artery walls. Ø Actuation of the pump allows drug delivery through micro-needles to the fatty cholesterol layer. Schematic diagram of the drug delivery process inside the heart artery Schematic diagram and photographs of the drug delivery system 3. FABRICATION Interdigitated electrodes fabrication process Micro-bellows membrane fabrication process 3D-Printing drug reservoir 4. CHARACTERIZATION & TEST Penetration test of a 200 μm long microneedle into PDMS film (Scale bar 50 μm) Parylene C micro-bellows membrane expansion using electrolysis Red-dye delivery through micro-needles using water electrolysis pump 5. CONCLUSION & FUTURE WORK Ø A new treatment method for coronary artery disease has been proposed Ø Fabrication of a micro-pump for drug delivery has been achieved Ø The assembly of the drug reservoir and micro-pump has been tested successfully Ø In process: Assembly of the drug delivery system on top of the balloon catheter
  • Driving Policy Transfer via Modularity and Abstraction

    Mueller, Matthias; Dosovitskiy, Alexey; Ghanem, Bernard; Koltun, Vladlen (2019-01-13) [Poster]
    Driving Policy Transfer via Modularity and Abstraction Summary ➢We transfer driving policies from simulation to reality via modularity and abstraction. ➢The driving policy is encapsulated such that it is not directly exposed to raw perceptual input or low-level vehicle dynamics. ➢We evaluate our approach in simulated urban environments and in various real-world conditions in two different continents. Simulation ➢We use CARLA, an open-source simulator for urban driving. ➢The simulator provides access to sensor data from the ego-vehicle, as well as detailed privileged information about the ego-vehicle and the environment. ➢CARLA provides access to two towns: Town 1 and Town 2 which differ in their layout, size, and visual style. ➢CARLA also provides multiple environmental conditions (combinations of weather and lighting). ➢We use two of these in our experiments: clear daytime and cloudy daytime after rain. ➢The two towns and environmental conditions used in our experiments are illustrated on the right. Physical World ➢We use a modified 1/5 scale Traxxas Maxx truck as vehicle. ➢At runtime, given an image, the onboard computer predicts the waypoints and uses a PID controller to convert them to low-level control commands. ➢While the car is driving, the driving policy can be guided by high-level command inputs through a switch on the remote control.
  • Graphene Oxide Liquid Crystal Membranes in Protic Ionic Liquid for Nanofiltration

    Mahalingam, Dinesh; Wang, Shaofei; Nunes, Suzana (2019-01-13) [Poster]
    Graphene Oxide Liquid Crystal Membranes in Protic Ionic Liquid for Nanofiltration Dinesh K Mahalingam, Shaofei Wang and Suzana P Nunes Graphene Oxide (GO) liquid crystals have been mostly reported as dispersion in water and organic solvents. They can provide highly ordered, regularly stacked nanochannels and lead ultrafast water transport and precise molecular sieving of solvated molecules. The main challenge is to obtain thin and robust layers with high water permeance and selectivity. We report GO liquid crystals from protic ionic liquid and exploit the self-assembled sheets to prepare nanofiltration membranes.

    Yuvaraja, Saravanan; Dhasmana, Hrishikesh; Kumar, Amit; Kumar, Vivek; Verma, Abhishek; Kumar Jain, Vinod; Nabil Salama, Khaled (2019-01-13) [Poster]
    Title: TIN OXIDE MODIFIED SILICON NANOWIRES ON SILICON CHIP AS AMMONIA SENSOR Authors: Saravanan Yuvaraja1,2, Hrishikesh Dhasmana2, Amit Kumar2, Vivek Kumar2, Abhishek Verma2, V. K. Jain2 and Khaled Salama1. Section 1: HOW YOU ARE EXPOSED TO AMMONIA ? Section 2: HOW AMMONIA AFFECTS YOUR HEALTH ? Section 3: WE CAN SAVE YOU FROM AMMONIA EXPOSURE Level 1: Synthesis Level 2: Performance analysis Level 3: Prototype demonstration Attention: Both Synthesis process flow and Gas sensing mechanism concept of the reported device architecture is presented in the video
  • Wind Resource Assessment and Characterization of Arabian Peninsula with Electrical Generation Estimation for Saudi Arabia

    Ilton De Oliveira Filho, Jose; Ombao, Hernando (2019-01-13) [Poster]
    Wind Resource Assessment and Characterization of Arabian Peninsula with Electrical Generation Estimation for Saudi Arabia SAUDI Arabia is a fast-growing country, with a stunning increased of Gross Domestic Product (GDP). To sustain this fast-growing rates, Saudi Arabia has continuously expanded its energy power plants. KSA has great potential for Wind Farms, but dust storms can be a major problem as it can increase the maintenance costs drastically. It was used two datasets to this project, the first dataset is from 89 weather stations across Saudi Arabia provided by the National Oceanic and Atmospheric Administration (NOAA) of the Integrated Surface Data (ISD) program. The second is from the weather forecast model produced by the National Centers for Environmental Prediction (NCEP). We also utilized the data presented in the work from 1, 2, 3 about the dust storm over middle East. From their work, we analyzed the Shamal wind current that affects Saudi Arabia with sessional dust storms and also the sources of dust in the Arabian Peninsula. The wind turbine generate electricity by transforming the kinectenergy provided by the wind on its blades. The Eolic energy can be observed as the theoretic energy potential of the site, and the power density of the wind can be express as: Where W(vb) is the estimated probability distribution made by Weibull distribution: As the data are acquired at 10m above ground level and the turbines are in different altitudes we used the exponential law for wind to extrapolate the airflow speed〖v〗_h. The annual energy production can be calculated by: The two figures below presents the overall mean direction (left) and wind speed for the Arabian peninsula with spatial resolution of 50km (right). By analyzing the regions with great wind speed average (>4.133m/s) at 10m hub-height above ground level (AGL), proximity to load centers, distance from dust storm path and long-term (>10 years) data available we ended up with two regions, Wejhand Prince Salman Bin Abdulaziz(PSBA) airport regions. The figure on the left shows the wind rose map for Wejh(region 1) and on the right for PSBA (region 2). Region2 presents 52.3% more power generation than Region 1 at a hub height of 112 meters. The power that can be generated by this region using only one turbine (16320 MW/a) is capable to power 3547 houses (using for this calculation the same power consumption of a normal house in UK) or 1395 houses (using for this calculation the same power consumption of a normal house in US). As a wind power farm has usually 50turbines, a wind farm installed in Region 2 could power 69750 residences using US standards of consumption. Thus, both regions combined, with a 50 turbine wind farm in each, could power 115540 houses (US standards of consumption). In thiswork we conducted the analyses of the wind pattern over Saudi Arabia with additional work on its surroundings, the Arabian Peninsula. By crossing results with previous works, we have observed that the North East and Central East of the country, despite showing good wind patternsfor this application, as it was presented on works 4-5, are not suitableregions to build wind farms, due to the incidence of sand storms.
  • Spatio-temporal pattern of UV attenuation in the Red Sea

    Overmans, Sebastian; Agusti, Susana (2019-01-13) [Poster]
    Background •Due to its close proximity to the equator and negligible cloud cover, the Red Sea receives one of the highest incident UV radiations globally (Acker et al., 2008) •The Red Sea is one of the most ultra-oligotrophic seas in the world with very little biomass (< 0.8 mg Chl m–3). During summer, an intense and stable water stratification occurs, with the consequence that surface layers become further exhausted in the already scarce nutrients •The lack of fluvial inputs and minimal amounts of CDOM due to low biomass mean the Red Sea could have one of the highest UV transparencies amongst marine water bodies (Helbling et al., 2003) •Since UV attenuation is strongly determined by the concentration of chlorophyll and CDOM, which vary spatially and temporally in the Red Sea, it is likely that attenuation changes accordingly •However, existing bio-optical Red Sea studies have predominantly been carried out in the far north and the Gulf of Aqaba in particular (Dishon et al., 2012). Aims The goal of this study was to establish baseline UV attenuation data for Red Sea coastal and pelagic sites across different seasons and along a broad latitudinal range. A further aim was to determine the contribution of Chl-a and CDOM towards UV attenuation in the Red Sea.
  • Shark Strike in the Northern Red Sea

    McIvor, Ashlie (2019-01-13) [Poster]
    A KAUST seaglider was attacked by a shark at approximately 09:10 Arabian Standard Time at a depth of 56.39m off the coast of Duba, Saudi Arabia. Seagliders are long-range autonomous underwater vehicles (AUVs) that can profile the ocean for many months at a time at a fraction of the cost of traditional methods. Shark attacks are a threat to the integrity of the data recorded by AUVs. This study quantifies the damage inflicted on the seaglider, as well as discussing the strike mechanics and potential attack motivation. Bite profiles were used to compare the inflicted damage on the Seaglider to the known pelagic species inhabiting the Red Sea. This included a tooth fragment and bite location on the Seaglider. Seaglider 213 was deployed from 5th October 2015 until an emergency recovery on the 14th November 2015, 70km offshore of Duba. During this time, communications with the glider had been challenging, where buoyancy and direction of the Seaglider were near impossible (blue spirals). The Seaglider had been struck twice. This created an ingress of water, severed oxygen sensor and removed a wing of the Seaglider (pink circle) causing difficulties in control. A second glider was struck during the summer of 2018. Heavy fishing in the Red Sea has reduced prey items. Pelagic sharks tend to display territorial behavior. Sharks are curious and test with their mouths; the color, noise, and biofouling could attract attention. The only records of shark attacks on AUVs have been from white sharks, which are not found in the Red Sea. Potential species include the Oceanic Whitetip and the Shortfin Mako. Future studies should focus on Artificial Intelligence software that can be developed to learn the normal patterns of vertical velocity, pitch, and roll of seagliders. Sharp and jagged movements are abnormal and could be interpreted as a shark strike to alert the Seaglider pilot in order to abort the mission. To identify the potential species of the attacks, pelagic baited remote underwater video surveys (BRUVS) should be conducted at the site of attack after a mission has been aborted due to a shark strike.
  • An Overview of Signal Processing Techniques for Terahertz UM-MIMO Systems

    Y. Al-Naffouri, Tareq; Sarieddeen, Hadi; Alouini, Mohamed-Slim (2019-01-13) [Poster]
    Signal Processing Techniques for Terahertz UM-MIMO Systems •THz communications promise Terabit/second data rates •Recent advancements in electronic, photonic, and plasmonic technologies are closing the gap in THz transceiver design •THz signal generation, modulation, and radiation methods are converging •Channel model, noise, and hardware-impairment notions are emerging •This paves the way to well-grounded research directions on THz-specific signal processing techniques for wireless communications
  • Temporal and Spatial Variations in Temperature and Salinity in the Mixed Layer from Changes in Latent Heat of Evaporation in the Red Sea

    Alejandra Perea Barreto, Maria; Kokkini, Zoi; Jones, Burton (2019-01-13) [Poster]
    Temporal and Spatial Variations in Temperature and Salinity in the Mixed Layer from Changes in Latent Heat of Evaporation in the Red Sea A time series analysis of the latent heat flux of evaporation, the temperature and the salinity was carried out for the Mixed Layer at two locations in the Red Sea. The month of March was analyzed for the northern region of Dubaand the more central location of KAUST. A longer time series spanning from January to September 2018 was analyzed for KAUST. Glider data of the temperature and the salinity in the Mixed Layer was combined with satellite measurements of heat fluxes for the analysis. The results show there is a high variability in the temperature and salinity within the Mixed Layer during the month of March. Temperature was anticorrelatedwith evaporation while salinity was positively correlated. For the whole year analysis, the sea response had a lag 6 days for temperature and 9 days for salinity at KAUST. The month of March showed a weaker relationship with a lag of 3 days for both temperature and salinity at KAUST. No significant relationship could be stablished at Duba. In general, it can be concluded that around the month of March when the evaporation decreases the advection term from the heat budget becomes more relevant and it obscures the correlation of Qe with T and S.
  • Compliant Lightweight Non-Invasive Standalone Marine Sensor Tagging System

    Mazo, Harold; Nassar, Johanna; F. Shaikh, Sohail; Mustafa Hussain, Muhammad (2019-01-13) [Poster]
  • SST Measurements in the Red Sea

    Shellem, Claire (2019-01-13) [Poster]
    Accuracy of satellite SST measurements compared to in-situ SST measurements in the central Red Sea: implications for coral bleaching studies
  • Approximate Computing with Stochastic Transistors' Voltage Over-scaling

    Li, Ren; Naous, Rawan; Salama, Khaled; Fariborzi, Hossein (2019-01-13) [Poster]
    Approximate Computing with Stochastic Transistors’ Voltage Over-scaling Introduction Approximate computing is a promising technique for error resilient applications. The intrinsic variability of the transistor (reflectedonVTH)is a concern for traditional designs. Thisworkaddresses the variation as the source of performance shaping in approximate computing. StochasticTransistorModel The physical variations are summed up into threshold voltage(VTH)variability; The variation is modeled by adding a thermal noise to the gate voltage. The added variability ensures Enoughdata points within a single transient simulation; The full spectrum of the Gaussian distribution is captured. Approximate Computing The worst-case scenario is guaranteed by assigning the obtained value “x” to the counterpart of its correct value. Voltageover-scaling scheme explores the designs pace of approximate full adder (FA) up to 16-bit. Designconsideration includes: Technology node Operating frequency Energy and delay Process corner Temperature Quantification on Approximate Adder Mean Error Distance (MED) describes the actual value of error. Mean Relative Error Distance (MRED) describes the deviation from the expected value. Image Compression Using Approximate Adder saves up to 90% energy while preserving relative quality. Conclusion The IoT (Internet of Things) operations which consist of numerous error resilient applications can benefit from this work. In conclusion, it Embraces and models the variability of the transistor; Adopts the inherent stochasticity in approximate computing; Provides design space and improved energy efficiency References R. Li, R. Naous, H. Fariborzi, and K. N. Salama, “Approximate Computing with Stochastic Transistors’ Voltage Over-scaling,” IEEE Access, 2018. DOI: 10.1109/ACCESS.2018.2889747 P. Weckx, et al, “Defect-centric perspective of combined BTI and RTN time-dependent variability,” in 2015 IEEE International Integrated Reliability Workshop (IIRW), pp. 21–28.
  • MVApp : Multivariate analysis application for streamlined data analysis and curation

    Julkowska, Magdalena; Saade, Stephanie; Agarwal, Gauraw; Gao, Ge; Pailles, Yveline; Morton, Mitchell; Awlia, Mariam; Tester, Mark (2019-01-13) [Poster]
    MVApp – Multivariate analysis application for streamlined data analysis and curation Mission statement: Enhanced data processing transparency Interactive and reproducible data curation Quick processing of data with/without selected outliers Increased statistical literacy across the scientific community Efficient data processing pipeline for big and small datasets Community involvement for expanding analyses included in MVApp
  • Multibit Storage devices

    wasef, shaik (2019-01-13) [Poster]

    Alothman, Afrah (2019-01-13) [Poster]
    The Importance of Osmo-mixotrophy in the Nutrition of the Diatom ThalassiosiraoceanicaUnder Iron Limitation Afrah Alothman, MSc thesis, Biology Department at Dalhousie University, Halifax, NS, Canada (July 2017). © Copyright by Afrah Alothman, 2017 Introduction: In general, photosynthetic carbon fixation by phytoplankton contributes significantly to carbon sequestration and storage in the deep ocean through the biological pump (Martin, 1990). Martin (1990) put forward the “iron hypothesis” that the rapid changes in CO2concentration in the atmosphere observed on geological timescales could be due to low phytoplankton productivity caused by iron deficiency in the HNLC regions. Diatoms such as Thalassiosira oceanica arevery plastic in their physiology and can acclimate to nutrient-limited conditions by down-regulating specific physiological processes in order to minimize demands for certain elements or nutrients, including iron (Lommer et al., 2012 & Chappell et al, 2015). This thesis aims to study the ‘osmo-mixotrophy’ defined as the utilization of organic substrates available in the environment(labile organic substrates) (Selosseet al, 2016) by autotrophic organism T. oceanica under iron replete and iron limited condition. Method: The isotope labelling experiments were designed to measure the uptake and the assimilation of inorganic (CO2) and organic carbon and nitrogen (Urea) by cells grown in iron-replete and iron-limited conditions incubated with either15N-nitrateor13C/15N-ureaas inorganic nitrogen and organic nitrogen source, respectively. Throughout the growth period, a series of physiological measurements were conducted (Table 1), and when the cells reach the exponential growth phase, cultures were harvested for incubating the isotope labelling samples(ILE). Results: 1- Thalassiosira oceanicacan grow osmo-mixotrophically (Figure 2, Figure 3). 2- Urea as an organic nitrogen and carbon source supported higher biomass than nitrate under iron limited condition(Figure 4) 3- Both C and N atoms from urea are assimilated by T. oceanica(Table 2). Conclusion Isotope labeling experiments with 13C-HCO3onate,15N-nitrate, and dual labeled 13C/15N urea showed that both N and C from the urea molecule were assimilated into cellular biomass by T. oceanica, though C uptake was at a lower rate than photosynthetic CO2fixation; the C/N uptake ratio was 0.15, which is less than the 0.5 C/N stoichiometric ratio of the urea molecule. In addition, the C uptake from urea under iron-limited and iron-replete conditions contributed from 5% ± 3.72to 11% ± 1.71 of total carbon assimilation. This was proportional to the fraction of urea-C relative to the total pool of dissolved carbon in the medium. In addition, the batch culture experiments suggested that, at equal dissolved N concentrations, urea supported a higher biomass than nitrate in iron-limited cultures. There was no significant difference in photosynthetic carbon fixation and nutrient uptake between the iron-limited and the iron-replete cultures. References: Chappell, P. D., Whitney, L. P., Wallace, J. R., Darer, A. I., Jean-Charles, S., & Jenkins, B. D. (2015). Genetic indicators of iron limitation in wild populations of Thalassiosira oceanicafrom the northeast Pacific Ocean. The ISME journal, 9(3), 592-602. Lommer, M., Specht, M., Roy, A. S., Kraemer, L., Andreson, R.,Gutowska, M. A., &LaRoche, J. (2012). Genome and low-iron response of an oceanic diatom adapted to chronic iron limitation. Genome biology, 13(7), R66. Martin, J. H. (1990). Glacial‐interglacial CO2 change: The iron hypothesis. Paleoceanography,5(1), 1-13.‏ Selosse, M. A., Charpin, M., & Not, F. (2016). Mixotrophyeverywhere on land and in water: the grand écarthypothesis. Ecology Letters.
  • Temporal and spatial variations in the age and growth of larval blue marlin Makaira nigricans in Cuba

    Fitzgerald, Lucy; Malca, Estrella; Gerard, Trika (2019-01-13) [Poster]
    Introduction Blue marlin, Makaira nigricans are the largest species in the Istiophoridae family. They are commercially important and are fished throughout the Gulf of Mexico and Caribbean Sea. Blue marlin fisheries are managed by the International Commission for the Conservation of Atlantic Tunas (ICCAT) along with NOAA’s NMFS Atlantic Highly Migratory Species. Blue marlin are listed as “vulnerable” on the IUCN red list due to population declines globally because of overfishing and management. Understanding the early life history dynamics of blue marlin are crucial for elucidating growth, spawning habitat, distribution, and survival. The larval stage is the most vulnerable (99% mortality) and is the base for life cycle. Larval studies have been conducted in the Gulf of Mexico, Straits of Florida, and the Bahamas (Serafy et al. 2003; Sponaugle et al. 2005), yet little is known regarding their early life history in and around Cuba which target blue marlin for fishing tournaments. Objectives: Develop an age and growth curve for larval blue marlin from Cuban waters. •Compare spatial variation in growth rates (north vs south stations). •Examine temporal variation between the 2015 and 2016 growth curves. Methods Collection •Ichthyoplankton collected during oceanographic surveys in May 2015 and 2016. •MOCNESS from 0-100 m in 25 m depth bins, neuston nets 0-10m, 0-50 m. •Genetically identified using species-specific PCR amplification of the ND4 mitochondrial DNA gene region in collaboration with the VIMS lab. Lab Analysis •Subset of larvae from a size and spatial distribution were selected for aging. •Otoliths (2 sagitta and 2 lapilli) were extracted when possible (n= 157). •Increments were blindly counted twice along the longest axis (reading axis). •Length at age was tested using a 2-way analysis of covariance (ANCOVA). Results •122 blue marlin from 38 stations (in 2015) and 55 blue marlin from 11 stations (in 2016) collected in Cuban waters (Figure 2). •Age growth curves were similar for both North (n=69) and South (42). •Temporal variation in growth was observed between 2015 (n=111) vs. 2016 (n=46). Conclusion •There was no significant difference in growth between the North and the South in 2015, however, there was a slightly faster growth rate (F=0.589, p=0.445) in the North (0.1159) compared to the South (0.0956) (a). •Temporal variation in the age growth curves were significantly higher in 2015 with a growth rate of 0.1069 compared to 2016, 0.0839 (F=25.7, p= < 0.001 ) (b). •The growth rates of blue marlin in Cuba is comparable to Sponaugle et al. 2005 (0.1282). Future Research •Examine whether environmental conditions (SST) are reflected in the variable growth observed between year and region. •Compare growth rates between istiophorid species: sailfish, white and black marlins found in adjacent water masses.
  • AUC-MF: Point of Interest Recommendation with AUC Maximization

    Han, Peng; Shang, Shuo; Sun, Aixin; Zhao, Peilin; Zheng, Kai; Kalnis, Panos (2019-01-13) [Poster]
    AUC-MF: Point of Interest Recommendation with AUC Maximization Location-based social networks (LSBNs) allow users to check in and share their experiences when they visit a point of interest (POI), such as a museum or a restaurant. With the development and popularity of various LSBN (Fig. 1) platforms e.g., BrightKite, Foursquare, and Gowalla, user check-in data is growing at an unprecedented pace. For instance, Foursquare had more than 50 million active users and more than 8 billion check-ins made by 2016. The availability of abundant amount of user check-in data, enables many studies on recommender systems to further enhance user experiences. POI recommendation aims at finding unvisited locations that a user may be interested in, by learning from users check-in history and other related factors. POI recommendation is challenging for many reasons. One of the most important reasons is that user check-in data is extremely sparse .

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