171 research outputs found

    Delocalization induced by low-frequency driving in disordered superlattices

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    We study the localization properties of disordered semiconductor superlattices driven by ac-fields. The localization length of the electrons in the superlattice increases when the frequency of the driving field is smaller than the miniband width. We show that there is an optimal value of the amplitude of the driving field for which the localization length of the system is maximal. This maximum localization length increases with the inverse of the driving frequency.Comment: 5 pages, 4 figure

    A Primitive Enzyme for a Primitive Cell: The Protease Required for Excystation of Giardia

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    AbstractProtozoan parasites of the genus Giardia are one of the earliest lineages of eukaryotic cells. To initiate infection, trophozoites emerge from a cyst in the host. Excystation is blocked by specific cysteine protease inhibitors. Using a biotinylated inhibitor, the target protease was identified and its corresponding gene cloned. The protease was localized to vesicles that release their contents just prior to excystation. The Giardia protease is the earliest known branch of the cathepsin B family. Its phylogeny confirms that the cathepsin B lineage evolved in primitive eukaryotic cells, prior to the divergence of plant and animal kingdoms, and underscores the diversity of cellular functions that this enzyme family facilitates

    Mid-Atlantic States Raccoon Rabies Outbreak

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    In the mid-1950s, an outbreak of raccoon rabies was recognized in South Florida and marked the beginning of epizootic/enzootic rabies in raccoons in this country. It spread at a rate of about 25 miles per year and currently includes eastern Alabama and most of Georgia and South Carolina. Up until the recent mid-Atlantic outbreak, the southern focus accounted for about 85 to 90% of the approximately 400 confirmed rabid raccoons reported in the United States each year

    Bibliografía de dorsales oceánicas

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    New record species of the Genus Microcyclops Claus,1893 (Crustacea:Copepoda:Cyclopoida) in the Holy Karbala Province / Iraq

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           تناول البحث  تسجيل  نوع  جديد  1863)  Microcyclops varicans (Sars      يعود  للجنس  1893 ، Microcyclops Claus  ، جمعت النماذج من محافظة كربلاء/قضاء الهندية بتاريخ 12-8-2015.يعد هذا النوع تسجلا ًجديداً للمجموعة العراقية  لرتبة Cyclopoida .  شخص النوع ووصف بالاستناد  الى صفات  المظهر الخارجي للجسم واللواحق والتي تميزه عن باقي الانواع العائدة للجنس Microcyclops . الجسم صغير ورفيع  ذو لون ابيض حليبي القطعة المزدوجة التناسلية متطاولة مع بروزات جانبية منتفخة من الامام, القطعة المخرجية مزودة بشويكات على طول الحافة الخلفية ظهرياً وبطنياً .الافرع الذنبية ملساء متساوية بالطول .  اللويمس  قصير  12 قطعة. السطح الخلفي  لللامس مزود بصفين من الاشواك المنحنية  بالقرب من منتصف الحافة الخارجية  . القطعة القاعدية للقدم الفكي Maxilliped  مزودة بصف من الشويكات .  القدم الداخلي والخارجي  للواحق القدمية  P1-P4  ذو قطعتين.   القطعة ما بين الحرقفتين   Intercoxa للP4  اصغر بقليل من باقي اللواحق P1-P3  . القطعة الثانية للقدم الداخلي End2 لل P3      مزودة  بشوكتان متساويتان بالطول قاعدة اللاحقة القدمية  الخامسة متصلة بالقطعة الجسمية الخامسة  مزودة بشوكة  قصيرة وهلب .   The present study introduce new record species Microcyclops varicans, (Sars ,1863). The samples of the study were collected from Al-hindiyah region in Holy Karbala governorate at 12.8.2015. The external morphological characters were used to recognize and describe the species under study and compare them with the related species of the genus Microcyclops , such characters are : body is small , thin , milky white , Anal segment with spinuls along the dorsal and ventral sides of its posterior surface ; Antenna supplied by two rows of curved spinuls near its middle external surface, both exopod and endopod are 2-segment ; intercoxa of the fourth pedigerous (P4) is slightly smaller than those of the first and third pedigerous ; base of the fifth pedigerous (P5) is connected with the fifth somite and with one short spine and one seta

    Prevalência de parasitas intestinais em população no sul do Teerã, Irã

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    The aim of this study was to describe epidemiologic characteristics of intestinal parasites in a population in south of Tehran, Iran. A retrospective cross-sectional study of patients with suspicious intestinal parasitic infections referred to the Zakaria Razi Laboratory in Shahre-Ray, southern Tehran, Iran, was conducted from April 21, 2004 to October 20, 2005. All stool samples were examined and socio-demographic informations were retrieved. Of 4,371 referred patients, 466 (239 males and 227 females) were laboratory diagnosed with intestinal parasites, with a period prevalence of 10.7%. Blastocystis hominis (B. hominis) and Giardia lamblia (G. lamblia) were the most frequent intestinal parasites. More than half of patients aged ³ 18 years had a low level of educational attainment (e.g. illiterate, primary school, high school) (170/331, 54.1%). Further, majority of patients were homemakers (42.3%, 140/331) or workers (28.1%, 93/331) employed in various business settings such as food industry and construction. Findings of this study showed that intestinal parasitic infections are still a major public health challenge in Iran that needs to be addressed. We believe that public education, improving sanitation conditions of underdeveloped areas/communities, community involvement, and supporting evidence-based practice/programs are the major keys to success in preventing the spread of intestinal parasitic infections in Iran.O própósito deste estudo foi descrever as características epidemiológicas dos parasitas intestinais em população do sul de Teerã, Irã. Um estudo retrospectivo seccional cruzado de pacientes com suspeita de infecções parasitárias intestinais enviados ao Laboratório Zakaria Razi em Shahre-Ray, sul do Teerã, Irã foi conduzido de 21 de abril de 2004 a 20 de outubro de 2005. Todas as amostras de fezes foram examinadas e as informações sócio-demográficas recuperadas. De 4371 pacientes enviados, 466 (239 homens e 227 mulheres) foram diagnosticados laboratorialmente como portadores de parasitas intestinais com prevalência no período de 10,7%. Blastocystis hominis (B. hominis) e Giardia lamblia (G. lamblia) foram os parasitas intestinais mais frequentes. Mais da metade dos pacientes ³ 18 anos tinham baixo nível educacional (por exemplo: analfabetos, escola primária, 2º grau completo) (170/331, 54,1%). Mais ainda, a maioria dos pacientes eram empregados domésticos (42,3%, 140/331) ou trabalhadores (28,1%, 93/331) empregados em diversos tipos de serviços, tais como a indústria de alimentos e construção. Achados deste estudo mostraram que as infecções parasitárias intestinais são ainda um desafio importante em saúde pública no Irã que necessita ser resolvido. Acreditamos que a educação pública, a melhoria das condições sanitárias em áreas pouco desenvolvidas/comunidades, envolvimento da comunidade, e programas práticos baseados nas evidências, são as principais chaves do sucesso na prevenção da disseminação das infecções parasitárias no Irã

    Lebanese Plants and Plant-Derived Compounds Against Colon Cancer

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    Colorectal cancer (CRC) is a major health concern and demands long-term efforts in developing strategies for screening and prevention. CRC has become a preventable disease as a consequence of a better understanding of colorectal carcinogenesis. However, current therapy is unsatisfactory and necessitates the exploration of other approaches for the prevention and treatment of cancer. Plant based products have been recognized as preventive with regard to the development of colon cancer. Therefore, the potential chemopreventive use and mechanism of action of Lebanese natural product were evaluated. Towards this aim the antitumor activity of Onopordum cynarocephalum and Centaurea ainetensis has been studied using in vitro and in vivo models. In vitro, both crude extracts were non cytotoxic to normal intestinal cells and inhibited the proliferation of colon cancer cells in a dose-dependent manner. In vivo, both crude extracts reduced the number of tumors by an average of 65% at weeks 20 (adenomas stage) and 30 (adenocarcinomas stage). The activity of the C. ainetensis extract was attributed to Salograviolide A, a guaianolide-type sesquiterpene lactone, which was isolated and identified through bio-guided fractionation. The mechanism of action of thymoquinone (TQ), the active component of Nigella sativa, was established in colon cancer cells using in vitro models. By the use of N-acetyl cysteine, a radical scavenger, the direct involvement of reactive oxygen species in TQ-induced apoptotic cells was established. The analytical detection of TQ from spiked serum and its protein binding were evaluated. The average recovery of TQ from spiked serum subjected to several extraction procedures was 2.5% proving the inability of conventional methods to analyze TQ from serum. This has been explained by the extensive binding (>98%) of TQ to serum and major serum components such as bovine serum albumin (BSA) and alpha-1-acid glycoprotein (AGP). Using mass spectrometry analysis, TQ was confirmed to bind covalently to the free cysteine in position 34 and 147 of the amino acid sequence of BSA and AGP, respectively. The results of this work put at the disposal for future development new plants with anti-cancer activities and enhance the understanding of the pharmaceutical properties of TQ, a prerequisite for its future clinical development.Paksusuolen syöpä on merkittävä terveyttä uhkaava sairaus ja vaatii pitkäjänteisiä ponnisteluita kehitettäessä lähestymistapoja taudin toteamiseksi ja hoitamiseksi. Paksusuolen syövän hoito on parantunut ja paksusuolen syövän kehittymiseen vaikuttavat tekijät tunnetaan paremmin kuin aikaisemmin. Kuitenkin nykyiset hoitokäytännöt eivät ole täysin tyydyttäviä ja tekevät välttämättömäksi, että tutkitaan muita tapoja ennalta ehkäistä ja hoitaa syöpää. On havaittu kasviperäisten tuotteiden estävän paksusuolen syövän kehittymistä. Tämän johdosta tässä tutkimuksessa libanonilaisten luonnontuotteiden syöpää estävää vaikutusta ja vaikutusmekanismia tutkittiin. Tutkittiin Onopordum cynarocephalum ja Centaurea ainetensis kasvien vaikutuksia paksusuolen syöpään käyttämällä in vitro and in vivo solu- ja eläinkoe malleja. In vitro, solukokeissa molemmat raakauutteet eivät olleet sytotoksisia suolistosoluille ja estivät paksusuolen syöpäsolujen lisääntymistä annosvasteisesti. In vivo, eläinkokeissa molemmat raakauutteet vähensivät kasvaimien määrää keskimäärin 65%:lla 20 viikkoa hoidon aloittamisesta (adenooma vaihe) and 30 viikkoa hoidon aloittamisesta (adenokarsinooma vaihe). C. ainetensis-uutteen aktiivisuus voitiin liittää Salograviolidi A:han, guaianolidi-tyyppinen seskviterpeenilaktoniin, mikä eristettiin ja tunnistettiin aktiivisuuden ohjaaman eristyksen avulla. Nigella sativa-kasvin vaikuttavan aineen tymokinonin (TQ) vaikutusmekanismia tutkittiin käyttämällä paksusuolen syöpäsolumalleja in vitro. Käyttämälllä N-asetyylikysteiiniä, radikaalin sieppaajaa, reaktiivisen happimolekyylien suora osallistuminen TQ-indusoiduissa apoptoottisissa soluissa voitiin osoittaa. TQ:n mittaamista seerumista ja TQ:n sitoutumista proteiineihin tutkittiin. Kun TQ oli lisätty seerumiin sen keskimääräinen saanto useiden uuttojen jälkeen oli vain 2.5%, mikä osoitti tavanomaisten menetelmien heikkouden analysoitaessa TQ:ta seerumista. Tämä selittyi TQ:n voimakkaalla sitoutumisella (>98%) seerumiin ja seerumin pääkomponentteihin kuten naudan seerumin albumiini (BSA) ja hapan glykoproteiini (alpha-1-acid glycoprotein, AGP). Käyttämällä massaspektrometri-analytiikkaa TQ:n voitiin osoittaa sitoutuvan kovalenttisesti vapaaseen kysteiiniin aminohappoissa 34 (BSA) ja 147 (AGP). Tämän työn tulokset mahdollistavat tulevaisuudessa uusien kasviperäisten syöpälääkkeiden kehittämisen ja edesauttavat TQ:n farmaseuttisten ominaisuuksien ymmärtämistä kehitettäessä sitä tulevaisuudessa lääkkeeksi kliiniseen käyttöön
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