1,289 research outputs found
Rancang Bangun API Part of Speech Tagger untuk Bahasa Indonesia Menggunakan Hidden Markov Model
Bahasa merupakan salah satu instrumen utama dalam interaksi
dan komunikasi antara manusia. Meskipun bahasa pada dasarnya bahasa
bertujuan untuk memudahkan, tidak bisa dipungkiri kalau perbedaan
bahasa merupakan salah satu kendala dalam komunikasi. Hal inilah yang
kemudian mendasari munculnya pemikiran untuk membuat perangkat
komputer yang tidak hanya sebagai alat, tapi sebagai sebuah entitas hidup
yang mampu berpikir dan berkomunikasi selayaknya manusia. Dan di
sinilah penelitian Natural Language Processing bermula.
Ketika pertama kali dikembangkan, komputer tidak dirancang
untuk bisa berpikir dan mampu berkomunikasi dengan manusia. Namun
seiring dengan perkembangan zaman, muncullah gagasan untuk membuat
komputer bisa memahami bahasa manusia. Karena dengan memahami
bahasa manusia, maka komputer akan bekerja dengan lebih efektif dan
efisien. Instruksi yang sebelumnya hanya dengan menggunakan bahasa
mesin, kini bisa diinstruksikan dengan menggunakan bahasa manusia.
Membuat komputer mampu memahami bahasa manusia bukanlah
hal yang sederhana. Pemrosesan bahasa alami merupakan sebuah proses
berkelanjutan dari banyak fase. Dan Part of speech tagging merupakan
salah satu proses awal dalam serangkaian proses yang ada dalam
pemrosesan bahasa alami.
Meskipun penelitian di bidang pemrosesan bahasa alami sudah
berlangsung sejak lama, sampai saat ini masih belum banyak ditemukan
sistem pemrosesan bahasa alami untuk bahasa Indonesia yang
komperhensif. Salah satu penyebabnya adalah karena tidak adanya modulmodul
yang bisa digunakan secara efektif dan efisien untuk
mengembangkan sistem pemrosesan bahasa alami untuk bahasa Indonesia.
Sehingga semua orang yang ingin melakukan penilitian di bidang
pemrosesan bahasa alami harus membuat modul-modul yang digunakan
dalam pemrosesan bahasa alami secara mandiri.
Guna meningkatkan efisiensi dan efektivitas dalam penelitian di
bidang pemrosesan bahasa alami, perlu dikembangkan modul part of
speech tagger yang bisa digunakan secara mudah. Sehingga pihak-pihak
yang ingin melakukan penelitian di bidang pemrosesan bahasa alami tidak
perlu membuat membuat modulnya secara mandiri.Untuk membuat modul
part of speech tagging, diperlukan teknik pemodelan dan perhitungan
secara probabilistik untuk menentukan jenis kata dari masing-masing
kalimat. Hidden Markov Model merupakan salah satu teknik pemodelan
dan perhitungan statistik probabalistik dengan tingkat akurasi yang tinggi.
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Language is one of the main instruments in the interaction
and communication between people. Although the language is
basically aiming to facilitate language, can not be denied that
differences in language is one of the obstacles in communication.
This is what underlies the emergence of the idea of making computer
devices that are not only as a tool, but as a living entity that is
capable of thinking and communicating properly human. And this is
where the research in Natural Language Processing began.
When first developed, computers are not designed to be able
to think and be able to communicate with humans. But along with the
times, there was the idea to make a computer can understand human
language. Because by understanding human language, then the
computer will work more effectively and efficiently. Instruction that
previously only by using machine language, can now be instructed
by human language.
Make computer to understand human language is not a
simple thing. Natural language processing is an ongoing process of
many phases. And part of speech tagging is one of the early process
in a series of processes that exist in natural language processing.
Although research in the field of natural language processing has
been going on for a long time, until now still not commonly found a
comprehensive natural language processing system for Indonesian language. One reason is the absence of modules that can be used
effectively and efficiently to develop a natural language processing
system for Indonesian. So that everyone who wants to do research in
the field of natural language processing must create modules that
are used in natural language processing independently.
In order to improve efficiency and effectiveness in research
in the field of natural language processing, need to be developed
part of speech tagger module that can be used easily. So that those
who want to do research in the field of natural language processing
does not need to make make the module by themselves. To make part
of speech tagging module, modeling engineering and calculation
probabilistic is necessary to determine what kind of part of speech of
each sentences. Hidden Markov Model is one modeling techniques
and statistical calculations probabalistik with a high degree of accuracy
Clinical assessment of a low-cost, hand-held, smartphone-attached intraoral imaging probe for ALA PDT monitoring and guidance
India has one of the highest rates of oral squamous cell carcinoma (OSCC) in the world, with an incidence of 15 per 100,000 and more than 70,000 deaths per year. The problem is exacerbated by lack of medical infrastructure and routine screening, especially in rural areas. This collaboration recently developed, and clinically validated, a low-cost, portable and easy-to-use platform for intraoral photodynamic therapy (PDT) specifically engineered for use in global health settings. Here, we explore the implementation of our low-cost PDT system in conjunction with a small, handheld smartphone-coupled, multichannel fluorescence and white-light oral cancer imaging probe, which was also developed for global health settings. Our study aimed to use this mobile intraoral imaging device for treatment guidance and monitoring PDT using 5-aminolevulinic acid (ALA)-induced protoporphyrin IX (PS; PpIX) fluorescence. A total of 12 patients with 14 lesions having moderately/well-differentiated micro-invasive OSCC lesions (<2 cm diameter, depth <5 mm) were systemically administered with three doses of 20mg/kg ALA (total 60mg/kg). Lesion site PpIX and auto fluorescence was analyzed before/after ALA administration, and again after light delivery (fractionated, total 100 J/cm^{2} of 630nm red LED light). Quantification of relative PpIX fluorescence enables lesion area segmentation to improve guidance of light delivery and reports extent of photobleaching. These results indicate the utility of this approach for image-guided PDT and treatment monitoring while also laying groundwork for an integrated approach, combining cancer screening and treatment with the same hardware
Competition between species can stabilize public-goods cooperation within a species
Competition between species is a major ecological force that can drive evolution. Here, we test the effect of this force on the evolution of cooperation within a species. We use sucrose metabolism of budding yeast, Saccharomyces cerevisiae, as a model cooperative system that is subject to social parasitism by cheater strategies. We find that when cocultured with a bacterial competitor, Escherichia coli, the frequency of cooperator phenotypes in yeast populations increases dramatically as compared with isolated yeast populations. Bacterial competition stabilizes cooperation within yeast by limiting the yeast population density and also by depleting the public goods produced by cooperating yeast cells. Both of these changes induced by bacterial competition increase the cooperator frequency because cooperator yeast cells have a small preferential access to the public goods they produce; this preferential access becomes more important when the public good is scarce. Our results indicate that a thorough understanding of species interactions is crucial for explaining the maintenance and evolution of cooperation in nature.United States. National Institutes of Health (GM085279‐02)National Science Foundation (U.S.) (PHY‐1055154)Alfred P. Sloan Foundation (BR2011‐066
Survey and scientific evaluation of medicinal plants used by the Pahan and Teli tribal communities of Natore district, Bangladesh
The Pahans and the Telis are two of the smallest indigenous communities in Bangladesh. The Pahans, numbering about 14,000 people are widely scattered in several northern districts of the country, while the Telis are such a small community that nothing has been reported on their numbers and lifestyle. Both tribes are on the verge of disappearance. One each of the Pahan and the Teli community was located after much search in two adjoining villages of Natore district, Bangladesh. Since the tribes were found to still depend on their traditional medicinal practitioners for treatment of ailments, it was the objective of the present study to document their traditional usage of medicinal plants and to evaluate such plants against modern research-based pharmacological activity studies on these plants. Interviews were conducted of the practitioners of the Pahan and Teli community of Natore district with the help of a semi-structured questionnaire and using the guided field-walk method. Plant specimens aspointed out by the practitioners were collected and pressed on the field and identification completed at the Bangladesh National Herbarium. The Pahan tribal practitioners used 13 plants distributed into 9 families for treatment of 14 different ailments. The Teli tribal practitioner used 15 plants divided into 14 families for treatment of 17 different ailments. Eight out of the thirteen plants used by the Pahan tribal practitioner (61.5%) had reported relevant pharmacological activities in the scientific literature, while six out of the fifteen plants used by the Teli tribal practitioners (40%) had such relevant pharmacological activities in accordance with their usage. The medicinal plants used by the Pahans and Telis warrant further scientific studies toward discovery of lead compounds and efficacious drugs and the documentation and protection of the traditional medical knowledge held by these tribes
Development of Photonic Crystal Fiber Based Gas/ Chemical Sensors
The development of highly-sensitive and miniaturized sensors that capable of
real-time analytes detection is highly desirable. Nowadays, toxic or colorless
gas detection, air pollution monitoring, harmful chemical, pressure, strain,
humidity, and temperature sensors based on photonic crystal fiber (PCF) are
increasing rapidly due to its compact structure, fast response and efficient
light controlling capabilities. The propagating light through the PCF can be
controlled by varying the structural parameters and core-cladding materials, as
a result, evanescent field can be enhanced significantly which is the main
component of the PCF based gas/chemical sensors. The aim of this chapter is to
(1) describe the principle operation of PCF based gas/ chemical sensors, (2)
discuss the important PCF properties for optical sensors, (3) extensively
discuss the different types of microstructured optical fiber based gas/
chemical sensors, (4) study the effects of different core-cladding shapes, and
fiber background materials on sensing performance, and (5) highlight the main
challenges of PCF based gas/ chemical sensors and possible solutions
Holographic Josephson Junctions and Berry holonomy from D-branes
We construct a holographic model for Josephson junctions with a defect system
of a Dp brane intersecting a D(p+2) brane. In addition to providing a
geometrical picture for the holographic dual, this leads us very naturally to
suggest the possibility of non-Abelian Josephson junctions characterized in
terms of the topological properties of the branes. The difference between the
locations of the endpoints of the Dp brane on either side of the defect
translates into the phase difference of the condensate in the Josephson
junction. We also add a magnetic flux on the D(p+2) brane and allow it evolve
adiabatically along a closed curve in the space of the magnetic flux, while
generating a non-trivial Berry holonomy.Comment: 20 pages, 2 figure
Topological Surface States Protected From Backscattering by Chiral Spin Texture
Topological insulators are a new class of insulators in which a bulk gap for
electronic excitations is generated by strong spin orbit coupling. These novel
materials are distinguished from ordinary insulators by the presence of gapless
metallic boundary states, akin to the chiral edge modes in quantum Hall
systems, but with unconventional spin textures. Recently, experiments and
theoretical efforts have provided strong evidence for both two- and
three-dimensional topological insulators and their novel edge and surface
states in semiconductor quantum well structures and several Bi-based compounds.
A key characteristic of these spin-textured boundary states is their
insensitivity to spin-independent scattering, which protects them from
backscattering and localization. These chiral states are potentially useful for
spin-based electronics, in which long spin coherence is critical, and also for
quantum computing applications, where topological protection can enable
fault-tolerant information processing. Here we use a scanning tunneling
microscope (STM) to visualize the gapless surface states of the
three-dimensional topological insulator BiSb and to examine their scattering
behavior from disorder caused by random alloying in this compound. Combining
STM and angle-resolved photoemission spectroscopy, we show that despite strong
atomic scale disorder, backscattering between states of opposite momentum and
opposite spin is absent. Our observation of spin-selective scattering
demonstrates that the chiral nature of these states protects the spin of the
carriers; they therefore have the potential to be used for coherent spin
transport in spintronic devices.Comment: to be appear in Nature on August 9, 200
Presence of RD149 Deletions in M. tuberculosis Central Asian Strain1 Isolates Affect Growth and TNFα Induction in THP-1 Monocytes
Central Asian Strain 1 (CAS1) is the prevalent Mycobacterium tuberculosis genogroup in South Asia. CAS1 strains carry deletions in RD149 and RD152 regions. Significance of these deletions is as yet unknown. We compared CAS1 strains with RD149 and concurrent RD149-RD152 deletions with CAS1 strains without deletions and with the laboratory reference strain, M. tuberculosis H37Rv for growth and for induction of TNFα, IL6, CCL2 and IL10 in THP-1 cells. Growth of CAS1 strains with deletions was slower in broth (RD149; p = 0.024 and RD149-RD152; p = 0.025) than that of strains without deletions. CAS1 strains with RD149 deletion strains further showed reduced intracellular growth (p = 0.013) in THP-1 cells as compared with strains without deletions, and also as compared with H37Rv (p = 0.007) and with CAS1 RD149-RD152 deletion strains (p = 0.029). All CAS1 strains induced higher levels of TNFα and IL10 secretion in THP-1 cells than H37Rv. Additionally, CAS1 strains with RD149 deletions induced more TNFα secretion than those without deletions (p = 0.013). CAS1 RD149 deletion strains from extrapulmonary sources showed more rapid growth and induced lower levels of TNFα and IL6 secretion in THP-1 cells than isolates from pulmonary sources. This data suggests that presence of RD149 reduces growth and increases the induction of TNFα in host cells by CAS1 strains. Differences observed for extrapulmonary strains may indicate an adaptation which increases potential for dissemination and tropism outside the lung. Overall, we hypothesise that RD149 deletions generate genetic diversity within strains and impact interactions of CAS1 strains with host cells with important clinical consequences
Photonic Analogue of Two-dimensional Topological Insulators and Helical One-Way Edge Transport in Bi-Anisotropic Metamaterials
Recent progress in understanding the topological properties of condensed
matter has led to the discovery of time-reversal invariant topological
insulators. Because of limitations imposed by nature, topologically non-trivial
electronic order seems to be uncommon except in small-band-gap semiconductors
with strong spin-orbit interactions. In this Article we show that artificial
electromagnetic structures, known as metamaterials, provide an attractive
platform for designing photonic analogues of topological insulators. We
demonstrate that a judicious choice of the metamaterial parameters can create
photonic phases that support a pair of helical edge states, and that these edge
states enable one-way photonic transport that is robust against disorder.Comment: 13 pages, 3 figure
Observation of Dirac plasmons in a topological insulator
Plasmons are the quantized collective oscillations of electrons in metals and
doped semiconductors. The plasmons of ordinary, massive electrons are since a
long time basic ingredients of research in plasmonics and in optical
metamaterials. Plasmons of massless Dirac electrons were instead recently
observed in a purely two-dimensional electron system (2DEG)like graphene, and
their properties are promising for new tunable plasmonic metamaterials in the
terahertz and the mid-infrared frequency range. Dirac quasi-particles are known
to exist also in the two-dimensional electron gas which forms at the surface of
topological insulators due to a strong spin-orbit interaction. Therefore,one
may look for their collective excitations by using infrared spectroscopy. Here
we first report evidence of plasmonic excitations in a topological insulator
(Bi2Se3), that was engineered in thin micro-ribbon arrays of different width W
and period 2W to select suitable values of the plasmon wavevector k. Their
lineshape was found to be extremely robust vs. temperature between 6 and 300 K,
as one may expect for the excitations of topological carriers. Moreover, by
changing W and measuring in the terahertz range the plasmonic frequency vP vs.
k we could show, without using any fitting parameter, that the dispersion curve
is in quantitative agreement with that predicted for Dirac plasmons.Comment: 11 pages, 3 figures, published in Nature Nanotechnology (2013
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