Cystine peptides Antiparallel β-sheet conformation of the cyclic biscystine peptide [Boc-Cys-Ala-Cys-NHCH3]2

The crystal structure analysis of the cyclic biscystine peptide [Boc-Cys1-Ala2-Cys3-NHCH3]2 with two disulfide bridges confirms the antiparallel ?-sheet conformation for the molecule as proposed for the conformation in solution. The molecule has exact twofold rotation symmetry. The 22-membered ring contains two transannular NH ? OC hydrogen bonds and two additional NH ? OC bonds are formed at both ends of the molecule between the terminal (CH3)3COCO and NHCH3 groups. The antiparallel peptide strands are distorted from a regularly pleated sheet, caused mainly by the L-Ala residue in which ?=� 155° and ?= 162°. In the disulfide bridge C? (1)-C? (1)-S(1)-(3')-C?(3')-C?(3'), S�S = 2.030 Å, angles C? SS = 107° and 105°, and the torsional angles are �49, �104, +99, �81, �61°, respectively. The biscystine peptide crystallizes in space group C2 with a = 14.555(2) Ã…, b = 10.854(2) Ã…, c = 16.512(2)Ã…, and ?= 101.34(1) with one-half formula unit of C30H52N8O10S4· 2(CH3)2SO per asymmetric unit. Least-squares refinement of 1375 reflections observed with |F| > 3?(F) yielded an R factor of 7.2%.

Tytöt, pojat ja sukupuolinen häirintä

In this research I ask what is interpreted as sex-based harassment by 15-16-year old girls and boys. By sex-based harassment I refer to one-sided, unwanted attention that is based on gender and that makes the target feel embarrassed, frightened, hurt or angry. My focus is not on the most overt cases of harassment but rather on everyday encounters. While young people differentiate between harassing and non-harassing attention, at the same time they define, assign value to and construct differences and power relations on the basis of gender, age and ethnicity, for example. My main data consists of essays (N 104, 54 girls, 54 boys) and thematic interviews (N 14; 20 girls, 3 boys) of ninth graders of a secondary school in Helsinki. In the essays and interviews, students construe the border between pleasant and unpleasant, tolerable and intolerable attention as clear in principle, but, they suggest that in practice this border is ambivalent, negotiable and contextual. The interpretations of incidents are justified by referring to features of the target, the scene or the perpetrator. Targets of harassment are most often construed as being girls who are characterized as thin-skinned, but at the same time they are expected to be understanding toward any sex-based attention they may get, particularly when it is not physical. On the other hand, girls are regarded as equal and even active participants in incidents of harassment. Such statements include considerations of how girls either reject or invite particular kinds of attention by their actions and outward appearance. Forms of harassment, ways of understanding it as well as overcoming it vary according to spatial context. By situating incidents in different spaces and places, young people contrast their experiences with ordinary and predictable non-harassment that takes place e.g. in discos and unusual and unexpected harassment that takes place e.g. in the city streets in the daytime. The behaviour of boys harassing a girls is naturalized by appealing to young masculinity and the childishness but also strong sexual drive which is seen as characteristic of teenage boys. On the other hand, sex-based harassment is racialized and pathologized in ways that separate the phenomenon from young, Finnish, normal masculinity. Both the material experiences of the young people and the definitions of the parties involved in harassing incidents are gendered. Girls encounter and deal with sexualized commenting and unwanted approaches much more often and in a more intensive way than boys. Furthermore, there is a vast cultural repertoire of acceptable accounts that can be mobilised in order to excuse male harassers, to critically evaluate the appearance or action of the female targets and to divide the responsibility between the female target and the male perpetrator.

Unfolding studies on soybean agglutinin and concanavalin a tetramers: A comparative account

The unfolding pathway of two very similar tetrameric legume lectins soybean agglutinin (SBA) and Concanavalin A ( ConA) were determined using GdnCl-induced denaturation. Both proteins displayed a reversible two-state unfolding mechanism. The analysis of isothermal denaturation data provided values for conformational stability of the two proteins. It was found that the DeltaG of unfolding of SBA was much higher than ConA at all the temperatures at which the experiments were done. ConA had a T-g 18 degreesC less than SBA. The higher conformational stability of SBA in comparison to ConA is largely due to substantial differences in their degrees of subunit interactions. Ionic interactions at the interface of the two proteins especially at the noncanonical interface seem to play a significant role in the observed stability differences between these two proteins. Furthermore, SBA is a glycoprotein with a GlcNac(2)Man(9) chain attached to Asn-75 of each subunit. The sugar chain in SBA lies at the noncanonical interface of the protein, and it is found to interact with the amino acid residues in the adjacent noncanonical interface. These interactions further stabilize SBA with respect to ConA, which is not glycosylated.

N-(7-Nitrobenz-2-oxa-1,3-diazol-4-yI)colcemid, a probe for different classes of colchincine-binding site on tubulin

The nature of binding of 7-nitrobenz-2-oxa-1,3-diazol-4-yl-colcemid (NBD-colcemid), an environment-sensitive fluorescent analogue of colchicine, to tubulin was tested. This article reports the first fluorometric study where two types of binding site of colchincine analogue on tubulin were detected. Binding of NBD-colcemid to one of these sites equilibrates slsowly. NBD-colcemid competes with colchicine for this site. Binding of NBD-colcemid to this site also causes inhibition of tubulin self-assembly. In contrast, NBD-colcemid binding to the other site is characterised by rapid equilibration and lack of competition with colchicine. Nevertheless, binding to this site is highly specific for the cholchicine nucleus, as alkyl-NBD analogues have no significant binding activity. Fast-reaction-kinetic studies gave 1.76 × 105 M–1 s–1 for the association and 0.79 s–1 for the dissociation rate constants for the binding of NBD-colcemid to the fast site of tubulin. The association rate constants for the two phases of the slow site are 0.016 × 10–4 M–1 s–1 and 3.5 × 10–4 M–1 respectively. These two sites may be related to the two sites of colchicine reported earlier, with binding characteristics altered by the increased hydrophobic nature of NBD-colcemid.

Tammen alueellisen levinneisyyden rajoitteet : Tapaustutkimus Länsi-Turunmaalla

Elinympäristön vaikutusta eliölajien esiintymiseen voidaan tutkia habitaattimallinnuksen keinoin. Havainnot lajin esiintymisestä ja puuttumisesta eri kohdissa maisemaa suhteutetaan tilastollisen mallin avulla ympäristötekijöihin, jolloin saadaan kuva lajin elinympäristövaatimuksista. Tällöin oletetaan, että laji esiintyy kaikkialla siellä, missä sen elinympäristövaatimukset täyttyvät. Metapopulaatioteorian valossa näin ei kuitenkaan aina ole: maisemassa voi olla runsaasti lajille soveltuvia mutta asuttamattomia kasvupaikkoja, koska uusien yksilöiden leviäminen ja vanhojen häviäminen eivät välttämättä ole yksittäisten kasvupaikkojen tasolla tasapainossa. Siten myös lajin leviämiskyky vaikuttaa siihen, millaiseksi sen levinneisyyskuvio maisematasolla muodostuu. Tässä työssä keskityn tammen (Quercus robur) alueellisen levinneisyyden mallintamiseen. Tammen suhteellinen harvinaisuus Suomessa sekä sen rooli luonnon monimuotoisuuden merkittävänä tukipilarina tekevät siitä mielenkiintoisen kohdelajin ekologiselle tutkimukselle. Tutkimuskohteekseni valitsin Wattkastin saaren, n. 5 km2:n alueen Länsi-Turunmaalta. Wattkastissa on tutkittu kahdeksan vuoden ajan tammella elävien hyönteisyhteisöjen rakennetta ja kannanvaihteluita, ja saaressa kasvaa yli 1800 luonnonvaraista tammea, joiden tarkat sijainnit tiedetään. Tässä ympäristössä tutkin, rajoittaako tammen alueellista levinneisyyttä ensisijaisesti sopivien elinympäristöjen tilajakauma vai pikemminkin sen leviämiskyky. Yhdistin tammen esiintymiskuviota kuvaavaan habitaattimalliin kokeellisen aineiston, jonka avulla arvioin tammen paikallisen esiintymiskuvion ja tammelle soveltuvien elinympäristöjen tilajakauman vastaavuutta. Kokeellisen aineiston muodostivat 104 Wattkastiin vuonna 2004 istutettua pikkutammea, joiden selviytymisen ja kasvupaikkaolot kartoitin syksyllä 2009. Tutkin yleistetyillä lineaarisilla malleilla puiden menestymiseen siis selviytymiseen ja kuntoon vaikuttavia tekijöitä. Etsin potentiaalisia selittäjiä tammen menestymiselle kasvupaikan ympäristötekijöistä sekä istutetun puun sijainnista suhteessa luontaisiin tammikasvustoihin. Lisäksi tutkin habitaattimallin avulla, selittävätkö ympäristötekijät tammen nykyisen esiintymiskuvion Wattkastissa. Havaitsin, että istutetut puut olivat selviytyneet keskimäärin hyvin ja ettei niiden menestyminen riippunut sijainnista suhteessa luontaisiin tammikasvustoihin. Habitaattimallin selitysaste oli vain 19 %, eli kasvupaikkatekijät selittivät heikosti tammen nykyisen esiintymiskuvion Wattkastissa. Tulosten perusteella tammen paikallinen esiintymiskuvio ei vastaa sille soveltuvien elinympäristöjen jakaumaa maisemassa, joten tammen levinneisyyttä Wattkastissa rajoittaa ilmeisesti sen leviämiskyky. Tulokseni viittaavat siihen, ettei tammen elinympäristön laadussa ole suuria vaihteluita Wattkastin sisällä, koska sopivia kasvupaikkoja on tarjolla tammen nykyesiintymiseen nähden runsaasti. Tämä on tammihyönteistutkimusten kannalta kiinnostava tulos, koska se tarkoittaa, että aiemmat havainnot isäntäpuun sijainnin ja hyönteisten kannanvaihteluiden välisestä yhteydestä edustavat todellisia, tilaan sidottuja populaatioprosesseja eivätkä isäntäpuun välittämiä eroja elinympäristön laadussa. Lisäksi tutkimukseni osoittaa, että yhdistämällä habitaattimallinnukseen kokeellinen lähestymistapa saadaan realistisempi kuva lajin levinneisyyttä rajoittavista tekijöistä kuin tutkimalla pelkästään ympäristötekijöiden vaikutusta lajin esiintymiseen. Jos lajin rajoittunut leviämiskyky on vaikuttanut sen esiintymiskuvion syntyyn, pelkästään ympäristötekijöihin perustuva levinneisyysmalli liioittelee levinneisyyttä. Kokeellisen tutkimuksen avulla on tällaisessa tapauksessa mahdollista paljastaa myös leviämiskyvyn rooli esiintymiskuvion taustalla.

Combination of Tevatron Searches for the Standard Model Higgs Boson in the W+W- Decay Mode

We combine searches by the CDF and D0 collaborations for a Higgs boson decaying to W+W-. The data correspond to an integrated total luminosity of 4.8 (CDF) and 5.4 (D0) fb-1 of p-pbar collisions at sqrt{s}=1.96 TeV at the Fermilab Tevatron collider. No excess is observed above background expectation, and resulting limits on Higgs boson production exclude a standard-model Higgs boson in the mass range 162-166 GeV at the 95% C.L.

Inclusive Search for Standard Model Higgs Boson Production in the WW Decay Channel using the CDF II Detector

We present a search for standard model (SM) Higgs boson production using ppbar collision data at sqrt(s) = 1.96 TeV, collected with the CDF II detector and corresponding to an integrated luminosity of 4.8 fb-1. We search for Higgs bosons produced in all processes with a significant production rate and decaying to two W bosons. We find no evidence for SM Higgs boson production and place upper limits at the 95% confidence level on the SM production cross section (sigma(H)) for values of the Higgs boson mass (m_H) in the range from 110 to 200 GeV. These limits are the most stringent for m_H > 130 GeV and are 1.29 above the predicted value of sigma(H) for mH = 165 GeV.

First Measurement of the b-Jet Cross Section in Events with a W Boson in pp̅ Collisions at √s=1.96 TeV

The cross section for jets from b quarks produced with a W boson has been measured in ppbar collision data from 1.9/fb of integrated luminosity recorded by the CDF II detector at the Tevatron. The W+b-jets process poses a significant background in measurements of top quark production and prominent searches for the Higgs boson. We measure a b-jet cross section of 2.74 +- 0.27(stat.) +- 0.42(syst.) pb in association with a single flavor of leptonic W boson decay over a limited kinematic phase space. This measured result cannot be accommodated in several available theoretical predictions.

Measurement of the WW+WZ Production Cross Section Using the lepton+jets Final State at CDF II

We report two complementary measurements of the WW+WZ cross section in the final state consisting of an electron or muon, missing transverse energy, and jets, performed using p\bar{p} collision data at sqrt{s} = 1.96 TeV collected by the CDF II detector. The first method uses the dijet invariant mass distribution while the second more sensitive method uses matrix-element calculations. The result from the second method has a signal significance of 5.4 sigma and is the first observation of WW+WZ production using this signature. Combining the results gives sigma_{WW+WZ} = 16.0 +/- 3.3 pb, in agreement with the standard model prediction.

Measurement of the Λb0 Lifetime in Λb0→Λc+π- Decays in pp̅ Collisions at √s=1.96 TeV

We report a measurement of the lifetime of the Lambda_b baryon in decays to the Lambda_C+ pi- final state in a sample corresponding to 1.1 fb^-1 collected in p-pbar collisions at sqrt(s) = 1.96 TeV by the CDF II detector at the Tevatron collider. Using a sample of about 3000 fully reconstructed Lambda_b events we measure tau(Lambda_b) = 1.401 +- 0.046 (stat) +- 0.035 (syst) ps (corresponding to c.tau(Lambda_b) = 420.1 +- 13.7 (stat) +- 10.6 (syst) um, where c is the speed of light). The ratio of this result and the world average B^0 lifetime yields tau(Lambda_b)/tau(B^0) = 0.918 +- 0.038 (stat and syst), in good agreement with recent theoretical predictions.

Search for Pair Production of Supersymmetric Top Quarks in Dilepton Events from pp̅ Collisions at √s=1.96 TeV

We present the results of a search for pair production of the supersymmetric partner of the top quark (the stop quark $\tilde{t}_{1}$) decaying to a $b$-quark and a chargino $\chargino$ with a subsequent $\chargino$ decay into a neutralino $\neutralino$, lepton $\ell$, and neutrino $\nu$. Using a data sample corresponding to 2.7 fb$^{-1}$ of integrated luminosity of $p\bar{p}$ collisions at $\sqrt{s} = 1.96$ TeV collected by the CDF II detector, we reconstruct the mass of candidate stop events and fit the observed mass spectrum to a combination of standard model processes and stop quark signal. We find no evidence for $\pairstop$ production and set 95% C.L. limits on the masses of the stop quark and the neutralino for several values of the chargino mass and the branching ratio ${\cal B}(\chargino\to\neutralino\ell^{\pm}\nu)$.

Search for Technicolor Particles Produced in Association with a W Boson at CDF

We present a search for the technicolor particles $\rho_{T}$ and $\pi_{T}$ in the process $p\bar{p} \to \rho_{T} \to W\pi_{T}$ at a center of mass energy of $\sqrt{s}=1.96 \mathrm{TeV}$. The search uses a data sample corresponding to approximately $1.9 \mathrm{fb}^{-1}$ of integrated luminosity accumulated by the CDF II detector at the Fermilab Tevatron. The event signature we consider is $W\to \ell\nu$ and $\pi_{T} \to b\bar{b}, b\bar{c}$ or $b\bar{u}$ depending on the $\pi_{T}$ charge. We select events with a single high-$p_T$ electron or muon, large missing transverse energy, and two jets. Jets corresponding to bottom quarks are identified with multiple $b$-tagging algorithms. The observed number of events and the invariant mass distributions are consistent with the standard model background expectations, and we exclude a region at 95% confidence level in the $\rho_T$-$\pi_T$ mass plane. As a result, a large fraction of the region $m(\rho_T) = 180$ - $250 \mathrm{GeV}/c^2$ and $m(\pi_T) = 95$ - $145 \mathrm{GeV}/c^2$ is excluded.

Search for Supersymmetry with Gauge-Mediated Breaking in Diphoton Events with Missing Transverse Energy at CDF II

We present the results of a search for supersymmetry with gauge-mediated breaking and $\NONE\to\gamma\Gravitino$ in the $\gamma\gamma$+missing transverse energy final state. In 2.6$\pm$0.2 \invfb of $p{\bar p}$ collisions at $\sqrt{s}$$=$1.96 TeV recorded by the CDF II detector we observe no candidate events, consistent with a standard model background expectation of 1.4$\pm$0.4 events. We set limits on the cross section at the 95% C.L. and place the world's best limit of 149\gevc on the \none mass at $\tau_{\tilde{\chi}_1^0}$$

Search for New Bottomlike Quark Pair Decays QQ̅ →(tW∓)(t̅ W±) in Same-Charge Dilepton Events

We report the most restrictive direct limits on masses of fourth-generation down-type quarks b′, and quarklike composite fermions (B or T5/3), decaying promptly to tW∓. We search for a significant excess of events with two same-charge leptons (e, μ), several hadronic jets, and missing transverse energy. An analysis of data from pp̅ collisions with an integrated luminosity of 2.7  fb-1 collected with the CDF II detector at Fermilab yields no evidence for such a signal, setting mass limits mb′, mB>338  GeV/c2 and mT5/3>365  GeV/c2 at 95% confidence level.

Search for WW and WZ Resonances Decaying to Electron, Missing ET, and Two Jets in pp̅ Collisions at √s=1.96 TeV.

Using data from 2.9  fb-1 of integrated luminosity collected with the CDF II detector at the Tevatron, we search for resonances decaying into a pair of on-shell gauge bosons, WW or WZ, where one W decays into an electron and a neutrino, and the other boson decays into two jets. We observed no statistically significant excess above the expected standard model background, and we set cross section limits at 95% confidence level on G* (Randall-Sundrum graviton), Z′, and W′ bosons. By comparing these limits to theoretical cross sections, mass exclusion regions for the three particles are derived. The mass exclusion regions for Z′ and W′ are further evaluated as a function of their gauge coupling strength.