123 research outputs found
PGPG: An Automatic Generator of Pipeline Design for Programmable GRAPE Systems
We have developed PGPG (Pipeline Generator for Programmable GRAPE), a
software which generates the low-level design of the pipeline processor and
communication software for FPGA-based computing engines (FBCEs). An FBCE
typically consists of one or multiple FPGA (Field-Programmable Gate Array)
chips and local memory. Here, the term "Field-Programmable" means that one can
rewrite the logic implemented to the chip after the hardware is completed, and
therefore a single FBCE can be used for calculation of various functions, for
example pipeline processors for gravity, SPH interaction, or image processing.
The main problem with FBCEs is that the user need to develop the detailed
hardware design for the processor to be implemented to FPGA chips. In addition,
she or he has to write the control logic for the processor, communication and
data conversion library on the host processor, and application program which
uses the developed processor. These require detailed knowledge of hardware
design, a hardware description language such as VHDL, the operating system and
the application, and amount of human work is huge. A relatively simple design
would require 1 person-year or more. The PGPG software generates all necessary
design descriptions, except for the application software itself, from a
high-level design description of the pipeline processor in the PGPG language.
The PGPG language is a simple language, specialized to the description of
pipeline processors. Thus, the design of pipeline processor in PGPG language is
much easier than the traditional design. For real applications such as the
pipeline for gravitational interaction, the pipeline processor generated by
PGPG achieved the performance similar to that of hand-written code. In this
paper we present a detailed description of PGPG version 1.0.Comment: 24 pages, 6 figures, accepted PASJ 2005 July 2
PROGRAPE-1: A Programmable, Multi-Purpose Computer for Many-Body Simulations
We have developed PROGRAPE-1 (PROgrammable GRAPE-1), a programmable
multi-purpose computer for many-body simulations. The main difference between
PROGRAPE-1 and "traditional" GRAPE systems is that the former uses FPGA (Field
Programmable Gate Array) chips as the processing elements, while the latter
rely on the hardwired pipeline processor specialized to gravitational
interactions. Since the logic implemented in FPGA chips can be reconfigured, we
can use PROGRAPE-1 to calculate not only gravitational interactions but also
other forms of interactions such as van der Waals force, hydrodynamical
interactions in SPH calculation and so on. PROGRAPE-1 comprises two Altera
EPF10K100 FPGA chips, each of which contains nominally 100,000 gates. To
evaluate the programmability and performance of PROGRAPE-1, we implemented a
pipeline for gravitational interaction similar to that of GRAPE-3. One pipeline
fitted into a single FPGA chip, which operated at 16 MHz clock. Thus, for
gravitational interaction, PROGRAPE-1 provided the speed of 0.96
Gflops-equivalent. PROGRAPE will prove to be useful for wide-range of
particle-based simulations in which the calculation cost of interactions other
than gravity is high, such as the evaluation of SPH interactions.Comment: 20 pages with 9 figures; submitted to PAS
Performance Tuning of N-Body Codes on Modern Microprocessors: I. Direct Integration with a Hermite Scheme on x86_64 Architecture
The main performance bottleneck of gravitational N-body codes is the force
calculation between two particles. We have succeeded in speeding up this
pair-wise force calculation by factors between two and ten, depending on the
code and the processor on which the code is run. These speedups were obtained
by writing highly fine-tuned code for x86_64 microprocessors. Any existing
N-body code, running on these chips, can easily incorporate our assembly code
programs.
In the current paper, we present an outline of our overall approach, which we
illustrate with one specific example: the use of a Hermite scheme for a direct
N^2 type integration on a single 2.0 GHz Athlon 64 processor, for which we
obtain an effective performance of 4.05 Gflops, for double precision accuracy.
In subsequent papers, we will discuss other variations, including the
combinations of N log N codes, single precision implementations, and
performance on other microprocessors.Comment: 32 pages, 2 figure
Effects of Arthroscopic Coracohumeral Ligament Release on Range of Motion for Patients with Frozen Shoulder
The tremendous potential of deep-sea mud as a source of rare-earth elements
金沢大学理工研究域地球社会基盤学系Potential risks of supply shortages for critical metals including rare-earth elements and yttrium (REY) have spurred great interest in commercial mining of deep-sea mineral resources. Deep-sea mud containing over 5,000 ppm total REY content was discovered in the western North Pacific Ocean near Minamitorishima Island, Japan, in 2013. This REY-rich mud has great potential as a rare-earth metal resource because of the enormous amount available and its advantageous mineralogical features. Here, we estimated the resource amount in REY-rich mud with Geographical Information System software and established a mineral processing procedure to greatly enhance its economic value. The resource amount was estimated to be 1.2 Mt of rare-earth oxide for the most promising area (105 km2 × 0-10 mbsf), which accounts for 62, 47, 32, and 56 years of annual global demand for Y, Eu, Tb, and Dy, respectively. Moreover, using a hydrocyclone separator enabled us to recover selectively biogenic calcium phosphate grains, which have high REY content (up to 22,000 ppm) and constitute the coarser domain in the grain-size distribution. The enormous resource amount and the effectiveness of the mineral processing are strong indicators that this new REY resource could be exploited in the near future. © 2018 The Author(s)
Fundamental optical processes in armchair carbon nanotubes
Single-wall carbon nanotubes provide ideal model one-dimensional (1-D) condensed matter systems in
which to address fundamental questions in many-body physics, while, at the same time, they are
leading candidates for building blocks in nanoscale optoelectronic circuits. Much attention has been
recently paid to their optical properties, arising from 1-D excitons and phonons, which have been
revealed via photoluminescence, Raman scattering, and ultrafast optical spectroscopy of semiconducting
carbon nanotubes. On the other hand, dynamical properties of metallic nanotubes have been poorly
explored, although they are expected to provide a novel setting for the study of electronヨhole pairs in
the presence of degenerate 1-D electrons. In particular, (n,n)-chirality, or armchair, metallic nanotubes
are truly gapless with massless carriers, ideally suited for dynamical studies of TomonagaヨLuttinger
liquids. Unfortunately, progress towards such studies has been slowed by the inherent problem of
nanotube synthesis whereby both semiconducting and metallic nanotubes are produced. Here, we use
post-synthesis separation methods based on density gradient ultracentrifugation and DNA-based ion-exchange chromatography to produce aqueous suspensions strongly enriched in armchair nanotubes.
Through resonant Raman spectroscopy of the radial breathing mode phonons, we provide macroscopic
and unambiguous evidence that density gradient ultracentrifugation can enrich ensemble samples in
armchair nanotubes. Furthermore, using conventional, optical absorption spectroscopy in the nearinfrared
and visible range, we show that interband absorption in armchair nanotubes is strongly
excitonic. Lastly, by examining the G-band mode in Raman spectra, we determine that observation of
the broad, lower frequency (G!) feature is a result of resonance with non-armchair “metallic”
nanotubes. These !ndings regarding the fundamental optical absorption and scattering processes in
metallic carbon nanotubes lay the foundation for further spectroscopic studies to probe many-body
physical phenomena in one dimension
A Kinetic Model of Dopamine- and Calcium-Dependent Striatal Synaptic Plasticity
Corticostriatal synapse plasticity of medium spiny neurons is regulated by glutamate input from the cortex and dopamine input from the substantia nigra. While cortical stimulation alone results in long-term depression (LTD), the combination with dopamine switches LTD to long-term potentiation (LTP), which is known as dopamine-dependent plasticity. LTP is also induced by cortical stimulation in magnesium-free solution, which leads to massive calcium influx through NMDA-type receptors and is regarded as calcium-dependent plasticity. Signaling cascades in the corticostriatal spines are currently under investigation. However, because of the existence of multiple excitatory and inhibitory pathways with loops, the mechanisms regulating the two types of plasticity remain poorly understood. A signaling pathway model of spines that express D1-type dopamine receptors was constructed to analyze the dynamic mechanisms of dopamine- and calcium-dependent plasticity. The model incorporated all major signaling molecules, including dopamine- and cyclic AMP-regulated phosphoprotein with a molecular weight of 32 kDa (DARPP32), as well as AMPA receptor trafficking in the post-synaptic membrane. Simulations with dopamine and calcium inputs reproduced dopamine- and calcium-dependent plasticity. Further in silico experiments revealed that the positive feedback loop consisted of protein kinase A (PKA), protein phosphatase 2A (PP2A), and the phosphorylation site at threonine 75 of DARPP-32 (Thr75) served as the major switch for inducing LTD and LTP. Calcium input modulated this loop through the PP2B (phosphatase 2B)-CK1 (casein kinase 1)-Cdk5 (cyclin-dependent kinase 5)-Thr75 pathway and PP2A, whereas calcium and dopamine input activated the loop via PKA activation by cyclic AMP (cAMP). The positive feedback loop displayed robust bi-stable responses following changes in the reaction parameters. Increased basal dopamine levels disrupted this dopamine-dependent plasticity. The present model elucidated the mechanisms involved in bidirectional regulation of corticostriatal synapses and will allow for further exploration into causes and therapies for dysfunctions such as drug addiction
Indian Monsoonal Variations During the Past 80 Kyr Recorded in NGHP-02 Hole 19B, Western Bay of Bengal: Implications From Chemical and Mineral Properties
金沢大学理工研究域地球社会基盤学系Detailed reconstruction of Indian summer monsoons is necessary to better understand the late Quaternary climate history of the Bay of Bengal and Indian peninsula. We established a chronostratigraphy for a sediment core from Hole 19B in the western Bay of Bengal, extending to approximately 80 kyr BP and examined major and trace element compositions and clay mineral components of the sediments. Higher δ 18 O values, lower TiO 2 contents, and weaker weathering in the sediment source area during marine isotope stages (MIS) 2 and 4 compared to MIS 1, 3, and 5 are explained by increased Indian summer monsoonal precipitation and river discharge around the western Bay of Bengal. Clay mineral and chemical components indicate a felsic sediment source, suggesting the Precambrian gneissic complex of the eastern Indian peninsula as the dominant sediment source at this site since 80 kyr. Trace element ratios (Cr/Th, Th/Sc, Th/Co, La/Cr, and Eu/Eu*) indicate increased sediment contributions from mafic rocks during MIS 2 and 4. We interpret these results as reflecting the changing influences of the eastern and western branches of the Indian summer monsoon and a greater decrease in rainfall in the eastern and northeastern parts of the Indian peninsula than in the western part during MIS 2 and 4. © 2018. American Geophysical Union. All Rights Reserved
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