695 resultados para Flyvbjerg, Bent
Resumo:
The electron transmission and bound state properties of a quantum wire with a sharp bend at arbitrary angle are studied, extending results on the right angle sharp bend (the L¿shaped wire). These new results are compared to those of a similar structure, the circular bend wire. The possibility of using a bent wire to perform transistor action is also discussed.
Resumo:
Here we discuss two consecutive MERLIN observations of the X-ray binary LS I +61° 303 . The first observation shows a double-sided jet extending up to about 200 AU on both sides of a central source. The jet shows a bent S-shaped structure similar to the one displayed by the well-known precessing jet of SS 433 . The precession suggested in the first MERLIN image becomes evident in the second one, showing a one-sided bent jet significantly rotated with respect to the jet of the day before. We conclude that the derived precession of the relativistic (beta=0.6) jet explains puzzling previous VLBI results. Moreover, the fact that the precession is fast could be the explanation of the never understood short term (days) variability of the associated gamma-ray source 2CG 135+01 / 3EG J0241+6103
Resumo:
This study aims to synthesize and characterize organoclays developed from an Argentinian montmorillonite (Bent) using hexadecyltrimethylammonium bromide (HDTMA-Br) as the intercalation agent. Subsequently, an adsorption mechanism is proposed. The obtained organoclays were more hydrophobic than the starting clay. Surfactant molecules were adsorbed initially through cation exchange in sites placed in the interlayer space of the clay. Adsorption in such sites continued until the interlayer space was saturated. Depending on the surfactant loading introduced during the intercalation process, different organizations of surfactant in the interlayer were obtained. Further adsorption of surfactant occurred in the mesopores generated by tactoids in the "house of cards" organization. This process kept surfactant molecules relatively free and out of the interlayer space.
Resumo:
Integrins are heterodimeric cell adhesion receptors involved in cell-cell and cell-extracellular matrix (ECM) interactions. They transmit bidirectional signals across the cell membrane. This results in a wide range of biological events from cell differentiation to apoptosis. alpha2beta1 integrin is an abundant collagen receptor expressed on the surface of several cell types. In addition to ECM ligands, alpha2beta1 integrins are bound by echovirus 1 (EV1) which uses alpha2beta1 as a receptor to initiate its life cycle in the infected cell. The aim of this thesis project was to provide further insight into the mechanisms of alpha2beta1 integrin ligand recognition and receptor activation. Collagen fibrils are the principal tensile elements of the ECM. Yet, the interaction of alpha2beta1 integrin with the fibrillar form of collagen I has received relatively little attention. This research focused on the ability of alpha2beta1 integrin to act as a receptor for type I collagen fibrils. Also the molecular requirements of the EV1 interaction with alpha2beta1 were studied. Conventionally, ligand binding has been suggested to require integrin activation and the binding may further trigger integrin signalling. Another main objective of this study was to elucidate both the inside-out and outside-in signalling mechanisms of alpha2beta1 integrin in adherent cells. The results indicated that alpha2beta1 integrin is the principal integrin-type collagen receptor for type I collagen fibrils, and alpha2beta1 may participate in the regulation of pericellular collagen fibrillogenesis. Furthermore, alpha2beta1 integrin inside-out activation appeared to be synergistically regulated by integrin clustering and conformational activation. The triggering of alpha2beta1 integrin outside-in signalling, however, was shown to require both conformational changes and clustering. In contrast to ECM ligands, EV1 appeared to take advantage of the bent, inactive form of alpha2beta1 integrin in initiating its life cycle in the cell. This research together with other recent studies, has shed light on the molecular mechanisms of integrin activation. It is becoming evident that large ligands are able to bind to the bent form of integrin, which has been previously considered to be physiologically inactive. Consequently, our understanding of the conformational modulation of integrins upon activation is changing.
Resumo:
Tässä diplomityössä on tutkittu särmäyksen eri muuttujien vaikutusta kustannusrakenteeseen. Tutkimusmenetelminä on käytetty kirjallisuusselvitystä sekä särmäysaikojen mittausta tuotannossa. Diplomityön tavoitteena oli saada aikaan kustannusperusteinen hinnoittelumalli, jonka avulla särmäyksen hinnoittelu on yksinkertaista ja nopeaa. Särmäysaikoja mitattiin erikokoisille ja -muotoisille kappaleille. Levyn paksuus mitattavilla kappaleilla oli alle 1mm. Muut mitat vaihtelivat alle 200 mm:stä yli 2000 mm:iin. Käytetyt materiaalit olivat sähkö- ja kuumasinkitty teräs. Mitattavia aikoja olivat aika, joka kuluu yhden särmän taivutukseen, aika, joka kuluu yhden kappaleen valmistamiseen sekä ohjelmointiin ja asetuksiin kuluva aika. Särmäysaikoihin vaikuttavat kymmenet eri muuttujat liittyen särmäyspuristimiin, särmättäviin kappaleisiin ja työkaluihin, jne. Osa muuttujista vaikuttaa hyvin vähän kokonaisaikaan, joten kaikkia muuttujia ei lähdetty mittaamaan erikseen. Lisäksi käytössä ollut mittausvälineistö ei ollut riittävän tarkka kaikkien muuttujien mittaamiseen. Aikaansaatu hinnoittelumalli huomioi eri muuttujat ajassa, joka kuluu kappaleiden valmistamiseen, jolloin kaikki muuttujat tulee huomioitua lopullisessa hinnassa.
Resumo:
Metastases are the major cause of cancer deaths. Tumor cell dissemination from the primary tumor utilizes dysregulated cellular adhesion and upregulated proteolytic degradation of the extracellular matrix for progeny formation in distant organs. Integrins are transmembrane adhesive receptors mediating cellcell and cellmatrix interactions that are crucial for regulating cell migration, invasion, proliferation, and survival. Consequently, increased integrin activity is associated with augmented migration and invasion capacity in several cancer types. Heterodimeric integrins consist of an alpha - and beta-subunit that are held together in a bent conformation when the receptor is inactive, but extension and separation of subdomains is observed during receptor activation. Either inside-out or outside-in activation of receptors is possible through the intracellular molecule binding to an integrin cytoplasmic domain or extracellular ligand association with an integrin ectodomain, respectively. Several regulatory binding partners have been characterized for integrin cytoplasmic beta-domains, but the regulators interacting with the cytoplasmic alpha-domains have remained elusive. In this study, we performed yeast two-hybrid screens to identify novel binding partners for the cytoplasmic integrin alpha-domains. Further examination of two plausible candidates revealed a significant coregulatory role of an integrin alpha-subunit for cellular signaling processes. T-cell protein tyrosine phosphatase (TCPTP) showed a specific interaction with the cytoplasmic tail of integrin alpha1. This association stimulated TCPTP phosphatase activity, leading to negative regulation of epidermal growth factor receptor (EGFR) signaling and diminished anchorage-independent growth. Another candidate, mammary-derived growth inhibitor (MDGI), exhibited binding to several different integrin cytoplasmic alpha-tails through a conserved GFFKR sequence. MDGI overexpression in breast cancer cells altered EGFR trafficking and caused a remarkable accumulation of EGFR in the cytoplasm. We further demonstrated in vivo that MDGI expression induced a novel form of anti-EGFR therapy resistance. Moreover, MDGI binding to α-tails retained integrin in an inactive conformation attenuating integrin-mediated adhesion, migration, and invasion. In agreement with these results, sustained MDGI expression in breast cancer patients correlated with an increased 10-year distant disease-free survival. Taken together, the integrin signaling network is far from a complete view and future work will doubtless broaden our understanding further.
Resumo:
Tämän työn tavoitteena oli kehittää esikäsittelymenetelmä, jolla voidaan reaaliaikaisesti vähentää hydrolysaatin ligniinipitoisuutta ja näin vähentää fluoresenssia hemiselluloosan analysoimisessa. Työn kirjallisuusosassa käsitellään hemiselluloosien rakennetta sekä niiden erottamista puusta, sekä käydään läpi hemiselluloosien käyttömahdollisuuksia ja niiden reaaliaikaiseen analysointiin soveltuvia tekniikoita. Kokeellisessa osassa tutkittiin ultrasuodatusta sekä adsorptiohartsikäsittelyä hydrolysaatin esikäsittelynä ennen Raman-analyysiä. Esikäsittelyn tavoitteena oli vähentää Raman-analyysia häiritsevää ligniinistä johtuvaa fluoresenssia. Suodatukset tehtiin Amicon-suodatuslaitteistolla käyttäen viittä eri suodatuskalvoa. Hartsikäsittelyissä käytettiin Amberliten XAD16 ja XAD7HP adsorbtiohartseja. Hartsisuhteina käytettiin 1/80, 1/40, 1/19 ja 1/13. Käytetyt ultrauodatuskalvot osoittautuivat suodatusnäytteistä tehtyjen HPLC-analyysien perusteella cut-off-luvultaan liian pieniksi, sillä hemiselluloosien ja ligniinin erotus ei onnistunut, vaan molemmat väkevöityivät konsentraattiin. Hartsikäsittelyillä saatiin ligniiniä poistettua aiheuttamatta hemiselluloosahäviöitä. Parhaimmillaan ligniinin poistumista kuvaava UV-absorbanssi pieneni hartsilla XAD16 37 % ja hartsilla XAD7 25 %. Vaikka ligniinipitoisuus aleni, näytteet fluoresoivat edelleen voimakkaasti Raman-mittauksessa. Tulosten perusteella näyttäisi siltä, että hartsikäsittelyä optimoimalla analyysiä häiritsevää fluoresenssia olisi edelleen mahdollista vähentää.
Resumo:
Kirja-arvio
Resumo:
The aim of this study was to compare different staining methods for the evaluation of sperm morphology by light microscopy and also to describe the morphometry of the entire sperm in collared peccaries (Pecari tajacu). Semen from 10 males was obtained by electroejaculation and evaluated for sperm motility, vigor, and concentration. Semen smears were prepared through three different staining methods: Bengal rose, brome-phenol blue, and eosin-nigrosin. Smears were evaluated under light microscopy and sperm morphologic alterations were determined in percentage. In addition, sperm morphometric analysis was conducted by light microscopy coupled to image analyzer software. The smears stained with Bengal Rose provide the best results for the visualization of the sperm tail, midpiece, and head. The use of eosin-nigrosin stain did not allow an adequate impregnation, and some sperm presented a few contrasts with the background. A higher incidence of bent coiled tails was verified in the use of brome-phenol blue staining (P<0.05). Through morphometric evaluation, it was observed that the tail occupies the greatest proportion (89%) of the sperm which presents a discretely elongated head. According to the results, the use of the Bengal Rose stain is recommended for the morphologic evaluation of the collared peccary sperm.
Resumo:
The Women's Literary Club of St. Catharines was founded in 1892 by a local author, Emma Harvey (Mrs. J.G.) Currie (1829-1913) and held its last official meeting on February 19, 1994. The Club developed, flourished and eventually waned. After more than one hundred successful years, the last members deposited the Club's archives at Brock University for the benefit of researchers, scholars and the larger community. The ‘object of the Club’ was established as “the promotion of literary pursuits.” The Club was a non-profit social organization composed of predominantly white, upper middle class women from the St. Catharines and surrounding areas. Club meetings were traditionally held fortnightly from March to December each year. The last meeting of the year was a celebration of their Club anniversary. The early meetings of the Club include papers presented and music performed by Club members. The literary pursuits that would dominate the agendas for the entire life of the Club reflected an interest in selected authors, national and local history, classical history, musical performances and current cultural and newsworthy events. For example in 1893 a typical meeting agendas would contain papers on Henry Wadsworth Longfellow, Hawaii, Brook Farm, Miss Louisa May Alcott and “Education of Women 100 years Ago.” Within the first year of the Club’s existence, detailed minute books became the norm and an annual agenda or program developed. The WLC collection contains a near complete set of meeting minutes from 1892 until 1995 and a comprehensive collection of yearly programs from 1983-1967 which members took great care to publish each year. Mrs. Currie brought together a group of women with a shared interest in literature and history, who wanted to pursue that interest in a formal and structured manner. She was well educated and influenced at an early age by her tutor and mentor William Kirby, local historian, writer and newspaper editor from Niagara-on-the-Lake. While Currie’s private education influenced her love of literature and history, the Club movement of the 1890’s offered a more public forum for her to share knowledge and learning with other women. Mrs. Currie was the wife of St. Catharines lawyer, James G. Currie, who also served as a Member of Parliament for the county of Lincoln. Mrs. W.H. McClive, who was also married to a St. Catharines lawyer, worked closely with Currie and they began research into the possibility of a literary Club in St. Catharines. Currie corresponded with a variety of literary Clubs across North America before she and Mrs.McClive tagged onto the momentum of the Club movement and published “A Clarion call for Women of St. Catharines To Form a Literary Club” in the local paper The St. Catharines Evening Journal. in 1892 and asked like Clubs to publish the news of their new Club. The early years of the WLC set the foundation of how the Club meetings and events would unfold for the next 80 plus years. Photos and minutes from the first ten years reveal an excitement and interest in organized Club outings. One particular event, an annual pilgrimage to the homestead of Laura Secord, became a yearly celebration for the Club. Club President, Mrs. Currie’s own personal work on Laura Secord amplified the Club’s interest in the ‘heroine of 1812’ and she allocated the profits from her publication on Secord in order to create a commemorative plaque/monument in the name of Laura Secord. The Club celebrated this event with a regular pilgrimage to this site. The connection felt by Club members and this memorial would continue until the Club’s last meetings. The majority of members in the early years were of the upper middle classes in the growing city of St. Catharines. Many of the charter members were the wives of merchants, business men, lawyers, doctors, even a hatter. Furthermore, the position of president was most often held by a woman with a comprehensive list of interests. This is particularly the case in Isabel Brighty McComb (1876-1941). Brighty who became a member in 1903, became Club president in 1932 and stayed in her post until her death in 1941. Similar to Mrs. Currie, Brighty was a local historian and published 2 booklets on local history. Her obituary indicates her position in the community as an author and involved community member committed to lifetime memberships in the Imperial Order of Daughters of Empire, I.O.D.E., the National Organization of Women, N.O.W. and the United Empire Loyalist Society, as well as the WLC. She was a locally known ‘teacher of elocution’ and a devoted researcher of Upper Canadian history. In a Club scrapbook dedicated to her, the biographical sketch illustrates the professionalism surrounding Brighty. There is very little personal history mentioned and the focus is on her literary works, her published essay, booklets and poetry. This professional focus, evident in both her obituary and the scrapbook, illustrate the diversity of these women, especially in their roles outside of the home. The WLC collection contains a vast array of essay, lectures clippings and scrapbooks from past meetings. Organized predominantly by topic or author, the folders and scrapbooks offer a substantial amount of research opportunity in the literary history of Canada. The dates, scope of topics and authors covered offer historians an exciting opportunity to examine the consumption of particular literary trends, artists and topics within the context of a midsized industrial city in English Canada. This is especially important because the agenda adhered to by the Club was bent on promoting, discussing and reviewing predominantly Canadian material. By connecting when and what these women were studying, scholars many gain a better understanding of the broader consumption and appreciation of literary and social trends of Canadian women outside of publishing and institutional records. Furthermore, because the agendas were set by and for these women, outside of the constructs of an institutionalized canon or agenda, they offer a fresh and on the ground examination of literary consumption over an extensive length of time.
Resumo:
The Active Isolated Stretching (AIS) technique proposes that by contracting a muscle (agonist) the opposite muscle (antagonist) will relax through reciprocal inhibition and lengthen without increasing muscle tension (Mattes, 2000). The clinical effectiveness of AIS has been reported but its mechanism of action has not been investigated at the tissue level. Proposed mechanisms for increased range of motion (ROM) include mechanical or neural changes, or an increased stretch tolerance. The purpose of the study was to investigate changes in mechanical properties, i.e. stiffness, of skeletal muscle in response to acute and long-term AIS stretching for the hamstring muscle group. Recreationally active university-aged students (female n=8, male n=2) classified as having tight hamstrings, by a knee extension test, volunteered for the study. All stretch procedures were performed on the right leg, with the left leg serving as a control. Each subject was assessed twice: at an initial session and after completing a 6-week AIS hamstring stretch training program. For both test sessions active knee extension (ROM) to a position of "light irritation", passive resisted torque and stiffness were determined before and after completion of the AIS technique (2x10 reps). Data were collected using a Biodex System 3 Pro (Biodex Medical Systems, NY, USA) isokinetic dynamometer. Surface electromyography (EMG) was used to monitor vastus lateralis (VL) and hamstring muscle activity during the stretching movements. Between test sessions, 2x10 reps of the AIS bent knee hamstring stretch were performed daily for 6-weeks.
Resumo:
An unidentified young Black gentleman poses beside a chair in this small tintype photograph. Both the name of the photographer and the date the photo was taken are unknown. The upper and lower left-hand corners have been cut and the tintype is slightly discolored and bent. This tintype was among the family memorabilia in the possession of Iris Sloman Bell, of St. Catharines, Ontario. The Bell - Sloman families are descended from former slaves from the United States."Tintypes were the invention of Prof. Hamilton Smith of Ohio. They begin as thin sheets of iron, covered with a layer of black paint. This serves as the base for the same iodized collodion coating and silver nitrate bath used in the ambrotype process. First made in 1856, millions were produced well into the twentieth century. When tintypes were finished in the same sorts of mats and cases used for ambrotypes, it can be almost impossible to distinguish which process was used without removing the image to examine the substrate." Source: American Museum of Photography http://www.photographymuseum.com/primer.html
Resumo:
This undated small black and white tintype, slightly scratched, discolored and bent with age, shows a group of Black men posing for an unknown photographer. There is handwritten signature scratched into the reverse which appears to read "B.J." and "Owen" (see digital image of reverse). The original also has a hand-drawn "X" over the face of the seated man in the middle. This tintype was in the possession of Iris Sloman Bell, of St. Catharines, Ontario. The Sloman - Bell family descendants include former American slaves who settled in Canada."Tintypes were the invention of Prof. Hamilton Smith of Ohio. They begin as thin sheets of iron, covered with a layer of black paint. This serves as the base for the same iodized collodion coating and silver nitrate bath used in the ambrotype process. First made in 1856, millions were produced well into the twentieth century. When tintypes were finished in the same sorts of mats and cases used for ambrotypes, it can be almost impossible to distinguish which process was used without removing the image to examine the substrate." Source: American Museum of Photography http://www.photographymuseum.com/primer.html
Resumo:
The Fenians were a group intent on securing Irish independence from England. The movement had its origins in Ireland in1857, under the leadership of James Stephens, with the assistance of John O'Mahony, an American who had raised funds for the cause. The American branch of this movement was especially successful, having raised $500 000 and enlisting about 10 000 American Civil War veterans. The group split into two separate factions, one desiring an invasion of Canada and the other preferring an uprising in Ireland. It soon became apparent that an uprising in Ireland was not imminent, and a decision was made to invade Canada. In April, 1866, a raid was launched against New Brunswick. It proved unsuccessful, and another raid was attempted on June 1, 1866, this time in Ridgeway, near Fort Erie, Ontario. The Canadian militiamen were defeated, but the Fenians subsequently withdrew. A third incident occurred on June 7, this time at Missisquoi Bay in Quebec, when the Fenians crossed the border, remained there for 2 days, and withdrew. A failed uprising in Ireland in 1867 signaled the demise of the movement. The Fenian threat helped to promote a sense of union among Canadians and provided an incentive for Confederation.
Resumo:
The Fenians were a group intent on securing Irish independence from England. The movement had its origins in Ireland in1857, under the leadership of James Stephens, with the assistance of John O'Mahony, an American who had raised funds for the cause. The American branch of this movement was especially successful, having raised $500 000 and enlisting about 10 000 American Civil War veterans. The group split into two separate factions, one desiring an invasion of Canada and the other preferring an uprising in Ireland. It soon became apparent that an uprising in Ireland was not imminent, and a decision was made to invade Canada. In April, 1866, a raid was launched against New Brunswick. It proved unsuccessful, and another raid was attempted on June 1, 1866, this time in Ridgeway, near Fort Erie, Ontario. The Canadian militiamen were defeated, but the Fenians subsequently withdrew. A third incident occurred on June 7, this time at Missisquoi Bay in Quebec, when the Fenians crossed the border, remained there for 2 days, and withdrew. A failed uprising in Ireland in 1867 signaled the demise of the movement. The Fenian threat helped to promote a sense of union among Canadians and provided an incentive for Confederation.