Search for: cytology
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    Reducing access latency of MLC PCMs through line striping

    , Article Proceedings - International Symposium on Computer Architecture ; Article number 6853228 , 14-18 June , 2014 , p. 277-288 ; ISSN: 10636897 ; ISBN: 9781479943968 Hoseinzadeh, M ; Arjomand, M ; Sarbazi-Azad, H ; Sharif University of Technology
    Although phase change memory with multi-bit storage capability (known as MLC PCM) offers a good combination of high bit-density and non-volatility, its performance is severely impacted by the increased read/write latency. Regarding read operation, access latency increases almost linearly with respect to cell density (the number of bits stored in a cell). Since reads are latency critical, they can seriously impact system performance. This paper alleviates the problem of slow reads in the MLC PCM by exploiting a fundamental property of MLC devices: the Most-Significant Bit (MSB) of MLC cells can be read as fast as SLC cells, while reading the Least-Significant Bits (LSBs) is slower. We propose... 

    Mid-defense: Mitigating protocol-level attacks in TOR using indistinguishability obfuscation

    , Article 2014 11th International ISC Conference on Information Security and Cryptology, ISCISC 2014 ; 3- 4 September , 2014 , pp. 214-219 ; ISBN: 9781479953837 Soltani, M ; Najafi, S ; Jalili, R ; Sharif University of Technology
    TOR is one of the most famous anonymity networks. TOR works correctly when at least one honest relay exists along an established circuit. However, many attacks reveal anonymity of TOR communications by watermarking traffics, changing timings, counting cells per packets, and recently, introducing errors in cells. This paper focuses on protocol-level attacks which can de-anonymize users by changing a cell, and provides a solution for this attack by changing the way integrities of cells are checked. The proposed design allows all relays, not just the exit node, to check the integrity of cells, independently. In addition, this paper proposes a novel method, based on the concept of... 

    Continuum model of actin-myosin flow

    , Article 2013 20th Iranian Conference on Biomedical Engineering, ICBME 2013 ; December , 2013 , Pages 98-102 Nikmaneshi, M. R ; Firoozabadi, B ; Saidi, M. S ; Sharif University of Technology
    IEEE Computer Society  2013
    The front part of a cell is divided to two regions called lamellum and lamellipodium (lamellipodial). This part plays an essential role for cell migration. Indeed, there are many protein filaments called actin in lamellum and lamellipodium, which induce the cell motion with polymerization in the leading edge of the cell. The actin filaments adhere to the extracellular matrix (ECM) by means of focal adhesions and they have contact by myosin motor proteins. The myosin motor proteins cause actin retrograde and anterograde flow exerted contractile stress on them. The focal adhesions exert frictional stress on the actin filaments. In this work, we developed a two-dimensional continuum model of... 

    Self-organization of developing embryo using scale-invariant approach

    , Article Theoretical Biology and Medical Modelling ; Volume 8, Issue 1 , 2011 ; 17424682 (ISSN) Tiraihi, A ; Tiraihi, M ; Tiraihi, T ; Sharif University of Technology
    Background: Self-organization is a fundamental feature of living organisms at all hierarchical levels from molecule to organ. It has also been documented in developing embryos. Methods. In this study, a scale-invariant power law (SIPL) method has been used to study self-organization in developing embryos. The SIPL coefficient was calculated using a centro-axial skew symmetrical matrix (CSSM) generated by entering the components of the Cartesian coordinates; for each component, one CSSM was generated. A basic square matrix (BSM) was constructed and the determinant was calculated in order to estimate the SIPL coefficient. This was applied to developing C. elegans during early stages of... 

    Using intra-line level pairing for graceful degradation support in PCMs

    , Article Proceedings of IEEE Computer Society Annual Symposium on VLSI, ISVLSI, 8 July 2015 through 10 July 2015 ; Volume 07-10-July-2015 , 2015 , Pages 527-532 ; 21593469 (ISSN) ; 9781479987184 (ISBN) Asadinia, M ; Sarbazi Azad, H ; Sharif University of Technology
    IEEE Computer Society  2015
    In Phase-Change Memory (PCM), the number of writes a cell can take before wearing-out is limited and highly varied due to unbalanced write traffic and process variation. After the failure of weak cells and in presence of large number of failed lines, some techniques have been proposed to further prolong the lifetime of a PCM device by remapping failed lines to spares and salvage a PCM device with graceful degradation. Others rely on handling failures through inter-line pairing. Observations reveal that most of cells in a line are healthy when the line is marked as faulty by any of these proposals. To overcome this deficiency, we propose Intra-line Level Pairing(ILP), a technique that... 

    A 32kb 90nm 10T-cell sub-threshold SRAM with improved read and write SNM

    , Article 2013 21st Iranian Conference on Electrical Engineering ; May , 2013 ; 9781467356343 (ISBN) Hassanzadeh, S ; Zamani, M ; Hajsadeghi, K ; Sharif University of Technology
    The constraints of power saving have compelled SRAM designers to consider sub-threshold area as a viable choice. The biggest barrier of this progress is the stability of SRAM's cells and the correct operations. In this paper a 10T cell structure has been proposed with 90% read and 50% write SNM improvement in comparison to the conventional 6T cell. The hold SNM value is about the 6T cell SRAM. Also using differential read method in the proposed structure causes high read performance and using simpler sense amplifier. The symmetric configuration of this structure helps the SRAM has simpler layout and lower transistor mismatch. Using 90nm TSMC CMOS, 32kb 10T cell SRAM in sub-threshold area is... 

    Designing and modeling a centrifugal microfluidic device to separate target blood cells

    , Article Journal of Micromechanics and Microengineering ; Volume 26, Issue 3 , 2016 ; 09601317 (ISSN) Shamloo, A ; Selahi, Aa ; Madadelahi, M ; Sharif University of Technology
    Institute of Physics Publishing  2016
    The objective of this study is to design a novel and efficient portable lab-on-a-CD (LOCD) microfluidic device for separation of specific cells (target cells) using magnetic beads. In this study the results are shown for neutrophils as target cells. However, other kinds of target cells can be separated in a similar approach. The designed microfluidics can be utilized as a point of care system for neutrophil detection. This microfluidic system employs centrifugal and magnetic forces for separation. After model validation by the experimental data in the literature (that may be used as a design tool for developing centrifugo-magnetophoretic devices), two models are presented for separation of... 

    Overlapped cells separation algorithm based on morphological system using distance minimums in microscopic images

    , Article 22nd Iranian Conference on Biomedical Engineering, 25 November 2015 through 28 November 2015 ; 2015 , Pages 263-268 ; 9781467393515 (ISBN) Khodadadi, V ; Fatemizadeh, E ; Setarehdan, S. K ; Sharif University of Technology
    Institute of Electrical and Electronics Engineers Inc 
    It is important to distinguish overlapped cell for tracking and segmentation biological cells from images. In this research, a novel or comprehensive method is provided with morphological features of cell and minimum distance for overlapped cells separation (OCS). it's necessary to say that this algorithm is not based on type and number of Overlapped cells. In this presented method based on a distance chart. At first, every cell or rectangle of cell is separated of the original image. Also, multiplex cell is distinguished by using minimum perimeter polygon (MPP) method. Distance chart is achieved on the base of morphological procedure and Computing of cell boundary distance to Cell middle... 

    Dielectrophoretic cell sorting via sliding cells on 3D silicon microelectrodes

    , Article Proceedings of the IEEE International Conference on Micro Electro Mechanical Systems (MEMS), 22 January 2017 through 26 January 2017 ; 2017 , Pages 147-150 ; 10846999 (ISSN) ; 9781509050789 (ISBN) Xing, X ; Chan, M. L ; Roshan, K. A ; Yobas, L ; Sharif University of Technology
    This work presents an innovative design for a flow-through dielectrophoretic cell sorting based on silicon bulk microelectrodes featuring sidewall undercuts. The microelectrodes are configured into an interdigitated array with digits extending across the flow chamber at an oblique angle against the flow stream. Target cells under dielectrophoretic forces and hydrodynamic drag can slide along the digits to a dedicated outlet. The design has been showcased for continuous-flow sorting of viable and non-viable mammalian cells, achieving a throughput of 16,600 cells/min, an order of magnitude higher than those reported for existing continuous-flow cell sorting designs using thin-film or... 

    Joint cell muting and user scheduling in multicell networks with temporal fairness

    , Article Wireless Communications and Mobile Computing ; Volume 2018 , 2018 ; 15308669 (ISSN) Shahsavari, S ; Akar, N ; Khalaj, B. H ; Sharif University of Technology
    Hindawi Limited  2018
    A semicentralized joint cell muting and user scheduling scheme for interference coordination in a multicell network is proposed under two different temporal fairness criteria. In the proposed scheme, at a decision instant, each base station (BS) in the multicell network employs a cell-level scheduler to nominate one user for each of its inner and outer sections and their available transmission rates to a network-level scheduler which then computes the potential overall transmission rate for each muting pattern. Subsequently, the network-level scheduler selects one pattern to unmute, out of all the available patterns. This decision is shared with all cell-level schedulers which then forward... 

    A high density and low power cache based on novel SRAM cell

    , Article Journal of Computers ; Volume 4, Issue 7 , 2009 , Pages 567-575 ; 1796203X (ISSN) Azizi Mazreah, A ; Manzuri, M. T ; Mehrparvar, A ; Sharif University of Technology
    Based on the observation that dynamic occurrence of zeros in the cache access stream and cache-resident memory values of ordinary programs exhibit a strong bias towards zero, this paper presents a novel CMOS five-transistor SRAM cell (5T SRAM cell) for very high density and low power cache applications. This cell retains its data with leakage current and positive feedback without refresh cycle. Novel 5T SRAM cell uses one word-line and one bit-line and extra read-line control. The new cell size is 17% smaller than a conventional six-transistor SRAM cell using same design rules with no performance degradation. Simulation and analytical results show purposed cell has correct operation during... 

    A survey on PCM lifetime enhancement schemes

    , Article ACM Computing Surveys ; Volume 52, Issue 4 , 2019 ; 03600300 (ISSN) Rashidi, S ; Jalili, M ; Sarbazi Azad, H ; Sharif University of Technology
    Association for Computing Machinery  2019
    Phase Change Memory (PCM) is an emerging memory technology that has the capability to address the growing demand for memory capacity and bridge the gap between the main memory and the secondary storage. As a resistive memory, PCM is able to store data based on its resistance values. The wide resistance range of PCM makes it possible to store even multiple bits per cell (MLC) rather than a single bit per cell (SLC). Unfortunately, PCM cells suffer from short lifetime. That means PCM cells could tolerate a limited number of write operations, and afterward they tend to permanently stick at a constant value. Limited lifetime is an issue related to PCM memory; hence, in recent years, many studies... 

    Effect of input voltage frequency on the distribution of electrical stresses on the cell surface based on single-cell dielectrophoresis analysis

    , Article Scientific Reports ; Volume 10, Issue 1 , 2020 Dastani, K ; Moghimi Zand, M ; Kavand, H ; Javidi, R ; Hadi, A ; Valadkhani, Z ; Renaud, P ; Sharif University of Technology
    Nature Research  2020
    Electroporation is defined as cell membrane permeabilization under the application of electric fields. The mechanism of hydrophilic pore formation is not yet well understood. When cells are exposed to electric fields, electrical stresses act on their surfaces. These electrical stresses play a crucial role in cell membrane structural changes, which lead to cell permeabilization. These electrical stresses depend on the dielectric properties of the cell, buffer solution, and the applied electric field characteristics. In the current study, the effect of electric field frequency on the electrical stresses distribution on the cell surface and cell deformation is numerically and experimentally... 

    Thermal conductivity of the cell membrane in the presence of cholesterol and amyloid precursor protein

    , Article Physical Review E ; Volume 102, Issue 4 , 2020 Rafieiolhosseini, N ; Ejtehadi, M. R ; Sharif University of Technology
    American Physical Society  2020
    The cell membrane is responsible for the transportation of heat between inside and outside the cell. Whether the thermal properties of the cell membrane are affected by the cholesterol concentration or the membrane proteins has not been investigated so far. Although the experimental measurement of the membrane thermal conductivity was not available until very recently, computational methods have been widely used for this purpose. In this study, we carry out molecular dynamics simulations to investigate the relation between the concentration of cholesterol and the thermal conductivity of a model membrane. Our results suggest an increase in the membrane thermal conductivity upon increasing the... 

    High-throughput, label-free isolation of white blood cells from whole blood using parallel spiral microchannels with u-shaped cross-section

    , Article Biosensors ; Volume 11, Issue 11 , 2021 ; 20796374 (ISSN) Mehran, A ; Rostami, P ; Saidi, M. S ; Firoozabadi, B ; Kashaninejad, N ; Sharif University of Technology
    MDPI  2021
    Rapid isolation of white blood cells (WBCs) from whole blood is an essential part of any WBC examination platform. However, most conventional cell separation techniques are labor-intensive and low throughput, require large volumes of samples, need extensive cell manipulation, and have low purity. To address these challenges, we report the design and fabrication of a passive, label-free microfluidic device with a unique U-shaped cross-section to separate WBCs from whole blood using hydrodynamic forces that exist in a microchannel with curvilinear geometry. It is shown that the spiral microchannel with a U-shaped cross-section concentrates larger blood cells (e.g., WBCs) in the inner... 

    X-ray diffraction analysis and williamson-hall method in usdm model for estimating more accurate values of stress-strain of unit cell and super cells (2 × 2 × 2) of hydroxyapatite, confirmed by ultrasonic pulse-echo test

    , Article Materials ; Volume 14, Issue 11 , 2021 ; 19961944 (ISSN) Rabiei, M ; Palevicius, A ; Dashti, A ; Nasiri, S ; Monshi, A ; Doustmohammadi, A ; Vilkauskas, A ; Janusas, G ; Sharif University of Technology
    MDPI AG  2021
    Taking into account X-ray diffraction, one of the well-known methods for calculating the stress-strain of crystals is Williamson-Hall (W–H). The W-H method has three models, namely (1) Uniform deformation model (UDM); (2) Uniform stress deformation model (USDM); and (3) Uniform deformation energy density model (UDEDM). The USDM and UDEDM models are directly related to the modulus of elasticity (E). Young’s modulus is a key parameter in engineering design and materials development. Young’s modulus is considered in USDM and UDEDM models, but in all previous studies, researchers used the average values of Young’s modulus or they calculated Young’s modulus only for a sharp peak of an XRD pattern... 

    Relationship between young’s modulus and planar density of unit cell, super cells (2 × 2 × 2), symmetry cells of perovskite (catio3) lattice

    , Article Materials ; Volume 14, Issue 5 , 2021 , Pages 1-15 ; 19961944 (ISSN) Rabiei, M ; Palevicius, A ; Nasiri, S ; Dashti, A ; Vilkauskas, A ; Janusas, G ; Sharif University of Technology
    MDPI AG  2021
    Calcium titanate-CaTiO3 (perovskite) has been used in various industrial applications due to its dopant/doping mechanisms. Manipulation of defective grain boundaries in the structure of perovskite is essential to maximize mechanical properties and stability; therefore, the structure of perovskite has attracted attention, because without fully understanding the perovskite structure and diffracted planes, dopant/doping mechanisms cannot be understood. In this study, the areas and locations of atoms and diffracted planes were designed and investigated. In this research, the relationship between Young’s modulus and planar density of unit cell, super cells (2 × 2 × 2) and symmetry cells of nano... 

    Application of exact continuum size-dependent theory for stability and frequency analysis of a curved cantilevered microtubule by considering viscoelastic properties

    , Article Engineering with Computers ; Volume 37, Issue 4 , 2021 , Pages 3629-3648 ; 01770667 (ISSN) Shariati, A ; Habibi, M ; Tounsi, A ; Safarpour, H ; Safa, M ; Sharif University of Technology
    Springer Science and Business Media Deutschland GmbH  2021
    The stability analysis of cantilevered curved microtubules in axons regarding various size elements and using the generalized differential quadrature method for solving equations is reported. The impacts of covering MAP Tau proteins along with cytoplasm are taken into account as the elastic medium. Curved cylindrical nanoshell considering thick wall is used to model the microtubules. The factor of length scale (l/R = 0.2) used in modified couple stress theory would result in more accuracy when it comes to comparison with experiments, while alternative theories presented in this paper provide less precise outcomes. Due to the reported precise results, at the lower value of the time-dependent... 

    Biomimetic ultraflexible piezoresistive flow sensor based on graphene nanosheets and PVA hydrogel

    , Article Advanced Materials Technologies ; 2021 ; 2365709X (ISSN) Abolpour Moshizi, S ; Moradi, H ; Wu, S ; Han, Z. J ; Razmjou, A ; Asadnia, M ; Sharif University of Technology
    John Wiley and Sons Inc  2021
    Flow sensors play a critical role in monitoring flow parameters, including rate, velocity, direction, and rotation frequency. In this paper, inspired by biological hair cells in the human vestibular system, an innovative flow sensor is developed based on polyvinyl alcohol (PVA) hydrogel nanocomposites with a maze-like network of vertically grown graphene nanosheets (VGNs). The VGNs/PVA hydrogel absorbs a copious amount of water when immersed in water, making the sensor highly sensitive to tiny stimuli underwater. The sensor demonstrates a high sensitivity (5.755 mV (mm s−1)−1) and extremely low velocity detection (0.022 mm s−1). It also reveals outstanding performance in detecting... 

    Prolonging lifetime of PCM-based main memories through on-demand page pairing

    , Article ACM Transactions on Design Automation of Electronic Systems ; Vol. 20, issue. 2 , 1 February , 2015 ; ISSN: 10844309 Asadinia, M ; Arjomand, M ; Sarbazi-Azad, H ; Sharif University of Technology
    With current memory scalability challenges, Phase-Change Memory (PCM) is viewed as an attractive replacement to DRAM. The preliminary concern for PCM applicability is its limited write endurance that results in fast wear-out of memory cells. Worse, process variation in the deep-nanometer regime increases the variation in cell lifetime, resulting in an early and sudden reduction in main memory capacity due to the wear-out of a few cells. Recent studies have proposed redirection or correction schemes to alleviate this problem, but all suffer poor throughput or latency. In this article, we show that one of the inefficiency sources in current schemes, even when wear-leveling algorithms are used,...