United States
United States
Time filter
Source Type

Tay A.,UCLACA | Tay A.,National University of Singapore | Murray C.,UCLACA | Owsley K.,UCLACA | And 3 more authors.
20th International Conference on Miniaturized Systems for Chemistry and Life Sciences, MicroTAS 2016 | Year: 2016

The lack of a platform to select magnetotactic bacteria mutants-of-interest have limited large scale production of biologically synthesized magnetic nanoparticles (MNPs) which have superior properties to chemically synthesized MNPs. Here, we describe a magnetic ratcheting system for live and quantitative isolation of Magnetospirillum magneticum (AMB-1) based on their number of MNPs. Using random chemical mutagenesis and magnetic selection, we generated a library of AMB-1 mutants including those that produce on average 2.2 fold more MNPs (∼25/cell) than wild-type AMB-1.

Nishida T.,Okayama University of Science | Kubota S.,Okayama University of Science | Kubota S.,Okayama University | Aoyama E.,Okayama University | And 3 more authors.
Osteoarthritis and Cartilage | Year: 2017

Objective CCN family protein 2/connective tissue growth factor (CCN2/CTGF) promotes cartilage regeneration in experimental osteoarthritis (OA) models. However, CCN2 production is very low in articular cartilage. The aim of this study was to investigate whether or not CCN2 was promoted by cultured chondrocytes treated with low-intensity pulsed ultrasound (LIPUS) and to clarify its mechanism. Methods Human chondrocytic cell line (HCS)-2/8, rat primary epiphyseal and articular cartilage cells, and Ccn2-deficient chondrocytes that impaired chondrocyte differentiation, were treated with LIPUS for 20 min at 3.0 MHz frequency and 60 mW/cm2 power. Expressions of chondrocyte differentiation marker mRNAs were examined by real-time PCR (RT-PCR) analysis from HCS-2/8 cells and Ccn2-deficient chondrocytes at 30 min and 1 h after LIPUS treatment, respectively. CCN2 production was examined by Western blotting after 5 h of LIPUS treatment. Moreover, Ca2+ influx was measured by using a Fluo-4 probe. Results The gene expression of chondrocyte differentiation markers and CCN2 production were increased in cultured chondrocytes treated with LIPUS. In addition, Ca2+ influx and phosphorylation of p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase (ERK)1/2 were increased by LIPUS treatment, and the stability of TRPV4 and BKca channel mRNAs was decreased by siRNA against CCN2. Consistent with those findings, the LIPUS-induced the gene expressions of type II collagen (COL2a1) and Aggrecan (ACAN) observed in wild-type cells were not observed in the Ccn2-deficient chondrocytes. Conclusion These data indicate that chondrocyte differentiation represented by CCN2 production was mediated via MAPK pathways activated by LIPUS-stimulated Ca2+ influx, which in turn was supported by the induced CCN2 molecules in articular chondrocytes. © 2016

Clemenson G.D.,La Jolla Salk Institute | Lee S.W.,La Jolla Salk Institute | Deng W.,La Jolla Salk Institute | Barrera V.R.,UCLACA | And 2 more authors.
Hippocampus | Year: 2015

Adult animals continue to modify their behavior throughout life, a process that is highly influenced by past experiences. To shape behavior, specific mechanisms of neural plasticity to learn, remember, and recall information are required. One of the most robust examples of adult plasticity in the brain occurs in the dentate gyrus (DG) of the hippocampus, through the process of adult neurogenesis. Adult neurogenesis is strongly upregulated by external factors such as voluntary wheel running (RUN) and environmental enrichment (EE); however, the functional differences between these two factors remain unclear. Although both manipulations result in increased neurogenesis, RUN dramatically increases the proliferation of newborn cells and EE promotes their survival. We hypothesize that the method by which these newborn neurons are induced influences their functional role. Furthermore, we examine how EE-induced neurons may be primed to encode and recognize features of novel environments due to their previous enrichment experience. Here, we gave mice a challenging contextual fear-conditioning (FC) procedure to tease out the behavioral differences between RUN-induced neurogenesis and EE-induced neurogenesis. Despite the robust increases in neurogenesis seen in the RUN mice, we found that only EE mice were able to discriminate between similar contexts in this task, indicating that EE mice might use a different cognitive strategy when processing contextual information. Furthermore, we showed that this improvement was dependent on EE-induced neurogenesis, suggesting a fundamental functional difference between RUN-induced neurogenesis and EE-induced neurogenesis. © 2014 Wiley Periodicals, Inc.

Jiang Y.,CA Technologies | Wang H.,University of California at Davis | Daneshrad B.,UCLACA | Fette B.,CA Technologies
Proceedings - IEEE Military Communications Conference MILCOM | Year: 2014

This paper studies physical (PHY) and MAC layer design for multi-antenna based mobile ad hoc networks (MANET). The central piece of the PHY layer design is a distributed transmit-receive (Tx-Rx) beam forming algorithm named the minimum interference leakage (MIL) beam former. With this algorithm, each pair of Tx-Rx nodes aims at maximizing the throughput of their own link while minimizing the interference leakage to the unintended ones. Besides the beam forming algorithm are other PHY functions, such as link selection and adaptation, and closed-loop power control (CLPC). To enable such a PHY design, we propose a slotted ALOHA-like MAC frame structure, based on which the PHY functional blocks can work in synergy to dramatically improve the network spectral efficiency. The simulation results show that the proposed design has nearly 100x gain over the single antenna baseline system using TDMA with QPSK rate 1/2, measured by the network area spectral efficiency. © 2014 IEEE.

Katsavrias C.,National and Kapodistrian University of Athens | Katsavrias C.,Aristotle University of Thessaloniki | Daglis I.A.,National and Kapodistrian University of Athens | Li W.,UCLACA | And 4 more authors.
Annales Geophysicae | Year: 2015

We present electron phase space density (PSD) calculations as well as concurrent Pc5 and chorus wave activity observations during two intense geomagnetic storms caused by interplanetary coronal mass ejections (ICMEs) resulting in contradicting net effect. We show that, during the 17 March 2013 storm, the coincident observation of chorus and relativistic electron enhancements suggests that the prolonged chorus wave activity seems to be responsible for the enhancement of the electron population in the outer radiation belt even in the presence of pronounced outward diffusion. On the other hand, the significant depletion of electrons, during the 12 September 2014 storm, coincides with long-lasting outward diffusion driven by the continuous enhanced Pc5 activity since chorus wave activity was limited both in space and time. © 2015 Author(s).

Yingst R.A.,Planetary Science Institute | Mest S.C.,Planetary Science Institute | Berman D.C.,Planetary Science Institute | Garry W.B.,Planetary Science Institute | And 13 more authors.
Planetary and Space Science | Year: 2014

We report on a preliminary global geologic map of Vesta, based on data from the Dawn spacecraft's High-Altitude Mapping Orbit (HAMO) and informed by Low-Altitude Mapping Orbit (LAMO) data. This map is part of an iterative mapping effort; the geologic map has been refined with each improvement in resolution. Vesta has a heavily-cratered surface, with large craters evident in numerous locations. The south pole is dominated by an impact structure identified before Dawn's arrival. Two large impact structures have been resolved: the younger, larger Rheasilvia structure, and the older, more degraded Veneneia structure. The surface is also characterized by a system of deep, globe-girdling equatorial troughs and ridges, as well as an older system of troughs and ridges to the north. Troughs and ridges are also evident cutting across, and spiraling arcuately from, the Rheasilvia central mound. However, no volcanic features have been unequivocally identified. Vesta can be divided very broadly into three terrains: heavily-cratered terrain; ridge-and-trough terrain (equatorial and northern); and terrain associated with the Rheasilvia crater. Localized features include bright and dark material and ejecta (some defined specifically by color); lobate deposits; and mass-wasting materials. No obvious volcanic features are evident. Stratigraphy of Vesta's geologic units suggests a history in which formation of a primary crust was followed by the formation of impact craters, including Veneneia and the associated Saturnalia Fossae unit. Formation of Rheasilvia followed, along with associated structural deformation that shaped the Divalia Fossae ridge-and-trough unit at the equator. Subsequent impacts and mass wasting events subdued impact craters, rims and portions of ridge-and-trough sets, and formed slumps and landslides, especially within crater floors and along crater rims and scarps. Subsequent to the formation of Rheasilvia, discontinuous low-albedo deposits formed or were emplaced; these lie stratigraphically above the equatorial ridges that likely were formed by Rheasilvia. The last features to be formed were craters with bright rays and other surface mantling deposits. Executed progressively throughout data acquisition, the iterative mapping process provided the team with geologic proto-units in a timely manner. However, interpretation of the resulting map was hampered by the necessity to provide the team with a standard nomenclature and symbology early in the process. With regard to mapping and interpreting units, the mapping process was hindered by the lack of calibrated mineralogic information. Topography and shadow played an important role in discriminating features and terrains, especially in the early stages of data acquisition. © 2013 Elsevier Ltd. All rights reserved.

Liang J.,University of Calgary | Donovan E.,University of Calgary | Nishimura Y.,UCLACA | Yang B.,University of Calgary | And 5 more authors.
Journal of Geophysical Research A: Space Physics | Year: 2015

Pulsating auroras often appear in forms of geo-stable or slowly convecting "patches." These patches can maintain their rough shape and size over many sequences of luminosity pulsations, yet they slowly drift with ionospheric E × B convection. Because of these characteristics, there has long been a speculation that the pulsating auroral patch (PAP) is connected to flux tubes filled with enhanced cold plasma. In this study, we perform a survey on pulsating auroral events when the footprints of low-Earth-orbit satellites traversed the PAPs, with a focus on the low-energy particle signatures associated with the PAPs. As a result, we identified, in a majority (∼2/3) of events, the existence of a low-energy ion precipitation structure that is collocated with the PAP, with core energies ranging from several tens of eV up to a few hundred eV. This result supports the hypothesis that a PAP connects to flux tubes filled with enhanced cold plasma. We further propose that the plasma outflows from the ionosphere are the origin of such cold plasma flux tubes. We suggest that the PAP is formed by a combination of high-energy electrons of a magnetospheric origin, the low-energy plasma structure of an ionospheric origin, and certain ELF/VLF waves that are intensified and modulated in interactions with both the hot and cold plasma populations. ©2015. American Geophysical Union. All Rights Reserved.

Wang H.,UC DavisCA | Jiang Y.,CA Technologies | Daneshrad B.,UCLACA | Fette B.,UC DavisCA
Proceedings - IEEE Military Communications Conference MILCOM | Year: 2014

This paper presents a solution for improving the network spectral efficiency (NSE) of a MIMO ad hoc network by simultaneously increasing the number of concurrent links in the network while maximizing the spectral efficiency of each. Our approach combines multiple physical layer techniques and balances the trade-offs of them. Assuming only the channel state information to the intended receiver, a two-level iterative algorithm is designed and presented. The inner loop uses an algorithm, which we refer to as the 'greedy MCS packing'(GMP), generates the generalized (eigen-) beam forming, performs power allocation and chooses proper modulation and coding scheme (MCS). The GMP attempts to maximize the rate while packing them in as few eigen-channels as possible. The outer loop is used for frequency sub-band selection. It uses a heuristic algorithm to choose the number of 'spectral segments' used by each TX-RX pair to further reduce overall network interference. Simulation results show that our algorithm yields as much as 71% improvement over a related previous work, which also combines multiple MIMO techniques and considers finite MCS rate with imperfect channel information. We further investigate the improvements in network spectral efficiency (NSE) when our baseline GMP approach is augmented by nonlinear Successive Interference Cancellation (SIC) at the receiver. While the NSE gain brought by this SIC-enhanced receiver is quite limited, our simulation shows that more concurrent links can be supported compared with GMP scheme using an MMSE receiver. © 2014 IEEE.

Jiang Y.,UCLACA | Daneshrad B.,UCLACA | Pottie G.,UCLACA
Proceedings - IEEE Military Communications Conference MILCOM | Year: 2015

As the next generation mobile ad hoc network (MANET) evolves to allow for multiple simultaneous transmissions within one-hop for higher spectral efficiency, the interferences from the peer nodes will pose a challenge to the initial acquisition in the MANET. In this paper, we propose a maximum likelihood (ML) method of initial acquisition of the preamble sequences. Simulations show that this proposed method is robust against the interferences. We also propose to use a pair of Zadoff-Chu (Z-C) sequences as the preamble. By exploiting the unique structure of the Z-C sequences, we can estimate both timing and frequency offsets through two fast Fourier transforms (FFT). The estimation of the channel response and the interference covariance is also obtained as a by-product. Simulation results verified that the presented method is efficient in interference suppression and may allow for dozens of simultaneous transmissions. © 2015 IEEE.

Gahm J.K.,UCLACA | Wisniewski N.,UCLACA | Kindlmann G.,University of Chicago | Kung G.L.,UCLACA | And 3 more authors.
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012

Purpose: Various methods exist for interpolating diffusion tensor fields, but none of them linearly interpolate tensor shape attributes. Linear interpolation is expected not to introduce spurious changes in tensor shape. Methods: Herein we define a new linear invariant (LI) tensor interpolation method that linearly interpolates components of tensor shape (tensor invariants) and recapitulates the interpolated tensor from the linearly interpolated tensor invariants and the eigenvectors of a linearly interpolated tensor. The LI tensor interpolation method is compared to the Euclidean (EU), affine-invariant Riemannian (AI), log-Euclidean (LE) and geodesic-loxodrome (GL) interpolation methods using both a synthetic tensor field and three experimentally measured cardiac DT-MRI datasets. Results: EU, AI, and LE introduce significant microstructural bias, which can be avoided through the use of GL or LI. Conclusion: GL introduces the least microstructural bias, but LI tensor interpolation performs very similarly and at substantially reduced computational cost. © Springer-Verlag Berlin Heidelberg 2012.

Loading UCLACA collaborators
Loading UCLACA collaborators