29,681 research outputs found
On a Result of Smith and Subbarao Concerning a Divisor Problem
No full textAbstractLet d(n;l,k) denote the number of divisors of the positive integer n which are congruent to I modulo k. The objective of the present paper is to prove that (for some exponent θ<⅓)holds uniformly in l, k and x satisfying 1≤l≤k≤x. This improves a recent result due to R. A. Smith and M. V. Subbarao [3].</jats:p
Crystallographic studies on the role of the C-terminal segment of human angiogenin in defining enzymatic potency
No full textHuman angiogenin (Ang) is an RNase in the pancreatic RNase superfamily that induces angiogenesis. Its catalytic activity is comparatively weak, but nonetheless critical for biological activity. The crystal structure of Ang has shown that enzymatic potency is attenuated in part by the obstructive positioning of Gln117 within the B1 pyrimidine binding pocket, and that the C-terminal segment of residues 117-123 must reorient for Ang to bind and cleave RNA. The native closed conformation appears to be stabilized by Gln117-Thr44 and Asp116-Ser118 hydrogen bonds, as well as hydrophobic packing of Ile119 and Phe120. Consistent with this view, Q117G, D116H, and I119A/F120A variants are 4-30-fold more active than Ang. Here we have determined crystal structures for these variants to examine the structural basis for the activity increases. In all three cases, the C-terminal segment remains obstructive, demonstrating that none of the residues that has been replaced is essential for maintaining the closed conformation. The Q117G structure shows no changes other than the loss of the side chain of residue 117, whereas those of D116H and I119A/F120A reveal C-terminal perturbations beyond the replacement site, suggesting that the native closed conformation has been destabilized. Thus, the interactions of Gln117 seem to be less important than those of residues 116, 119, and 120 for stabilization. In D116H, His116 does not replicate either of the hydrogen bonds of Asp116 with Ser118 and instead forms a water-mediated interaction with catalytic residue His114; residues 117-121 deviate significantly from their positions in Ang. In I119A/F120A, the segment of residues 117-123 has become highly mobile and all of the interactions thought to position Gln117 have been weakened or lost; the space occupied by Phe120 in Ang is partially filled by Arg101, which has moved several angstroms. A crystal structure was also determined for the deletion mutant des(121-123), which has 10-fold reduced activity toward large substrates. The structure is consistent with the earlier proposal that residues 121-123 form part of a peripheral substrate binding subsite, but also raises the possibility that changes in the position of another residue, Lys82, might be responsible for the decreased activity of this variant
Measurement of the ratio of branching fractions B(B0→K∗0γ )/B(B0s→φγ ) and the directCP asymmetry inB 0→K∗0γ
No full textThe ratio of branching fractions of the radiative B decays B0→K⁎0γ and B0s→ϕγ has been measured using an integrated luminosity of 1.0 fb−1 of pp collision data collected by the LHCb experiment at a centre-of-mass energy of s√=7TeV. The value obtained is
B(B0→K⁎0γ)B(B0s→ϕγ)=1.23±0.06(stat.)±0.04(syst.)±0.10(fs/fd),
where the first uncertainty is statistical, the second is the experimental systematic uncertainty and the third is associated with the ratio of fragmentation fractions fs/fd. Using the world average value for B(B0→K⁎0γ), the branching fraction B(B0s→ϕγ) is measured to be (3.5±0.4)×10−5.
The direct CP asymmetry in B0→K⁎0γ decays has also been measured with the same data and found to be
ACP(B0→K⁎0γ)=(0.8±1.7(stat.)±0.9(syst.))%.
Both measurements are the most precise to date and are in agreement with the previous experimental results and theoretical expectations
Genetic diversity and population biology of a global collection of phytopathogenic Verticillium dahliae
No full textEstablishment of the contemporary Slovenian author
No full textKoncept avtorja se je skozi čas spreminjal. V antiki je avtor veljal za avtoriteto, vzor in genija, v (post)strukturalizmu, ko je osrednje mesto zavzel tekst, so razglašali avtorjevo smrt, v današnjem času hiperprodukcije literature pa je ponovno obujen, njegova vloga pa korenito predrugačena: avtor s tem, ko sodeluje v promociji, književnemu delu omogoča preživetje. Avtor, ki se ne želi tržiti, na književnem trgu posledično obstane le s težavoče želi, da njegovo delo ni spregledano, mora biti viden in se zavestno uveljavljati. Prav proces uveljavljanja raziskujem tudi v svoji magistrski nalogi. Podrobneje me zanima, katere entitete omogočajo avtorjevo uveljavljanje in do kakšne mere se kot posameznik lahko zoperstavlja tržni logiki. Ker odločilno vlogo v tem procesu igrajo mediji in založbe, sem opravila intervjuje s petimi slovenskimi medijskimi uredništvi (in raziskala, na kak način izbirajo avtorje, o katerih poročajo, kako skrbijo za uravnovešenost, na kak način prestavljajo avtorje ipd.) ter s šestimi založbami (zanimalo me je, kako pristopajo k promociji, kakšni avtorji so zanje zanimivi, kako sodelujejo z mediji ipd.). Kot pomemben faktor v procesu uveljavljanja oboji omenjajo literarne nagrade, predvsem nagrado kresnik, ki jo podeljuje časnik Delo – vlogi slednje se posvečam v zadnjem poglavju. V sklepu izpostavljam dobre prakse, ki v slovenskem prostoru prispevajo k uveljavljanju še neuveljavljenih avtorjev, in podajam predloge izboljšav, do katerih bi lahko prišlo v medijih in založništvu.The concept of the author has changed over time. In antiquity, the author was considered an authority, a role model and a geniusin (post-)structuralism, when the text took centre stage, the death of the author was proclaimedin today\u27s age of the hyperproduction of literature, the author has been revived, and his/her role radically reshaped: the author, by taking part in the promotion, enables the literary work to survive. The author who does not want to market himself/herself will consequently find it difficult to stay on the literary marketif he/she wants his/her work not to be overlooked, he/she must be visible and consciously assert himself/herself. In my master’s thesis, this process of assertion has been explored. In more detail, I am interested in which entities enable the author to assert himself/herself and to what extent can he/she as an individual challenge the logic of the market. Since the media and publishing houses play a decisive role in this process, I interviewed five Slovenian media editorial offices (to find out how they choose the authors they cover, how they ensure balance, how they shift authors, etc.) and six publishing houses (to find out how they approach promotion, which authors are interesting to them, how they cooperate with the media, etc.). Both mention literary prizes as an important factor in the process of promotion, especially the kresnik prize awarded by the Delo newspaper – the role of the latter is discussed in the last chapter. In the conclusion, good practices that contribute to the promotion of non-established authors in Slovenia are highlighted and suggestions for improvements that could be made in the media and publishing are listed
Branching fraction and CP asymmetry of the decays B+→K0Sπ+ and B+→K0SK+
No full textAn analysis of B+ → K0
Sπ+ and B+ → K0
S K+ decays is performed with the LHCb experiment. The pp
collision data used correspond to integrated luminosities of 1 fb−1 and 2 fb−1 collected at centre-ofmass
energies of
√
s = 7 TeV and
√
s = 8 TeV, respectively. The ratio of branching fractions and the
direct CP asymmetries are measured to be B(B+ → K0
S K+
)/B(B+ → K0
Sπ+
) = 0.064 ± 0.009 (stat.) ±
0.004 (syst.), ACP(B+ → K0
Sπ+
) = −0.022 ± 0.025 (stat.) ± 0.010 (syst.) and ACP(B+ → K0
S K+
) =
−0.21 ± 0.14 (stat.) ± 0.01 (syst.). The data sample taken at
√
s = 7 TeV is used to search for
B+
c
→ K0
S K+ decays and results in the upper limit ( fc · B(B+
c
→ K0
S K+
))/( fu · B(B+ → K0
Sπ+
)) <
5.8 × 10−2 at 90% confidence level, where fc and fu denote the hadronisation fractions of a ¯b
quark
into a B+
c or a B+ meson, respectively
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
K-theory for group C*-algebras
No full textThese notes are based on a lecture course given by the first author in the Sedano Winter School on K-theory held in Sedano, Spain, on January 22-27th of 2007. They aim at introducing K-theory of C*-algebras, equivariant K-homology and KK-theory in the context of the Baum-Connes conjectur
The book of author about walking
No full textAutorská kniha na téma chůze předává mou osobní výpověď skrze texty a ilustrace. Představuje čtenáři pohled na chůzi jako prostředek k meditaci a k uvědomění. Vede ho k žití v přítomnosti a k všímavosti k sobě i okolí, především ke krásám přírody a jejím proměnám.ObhájenoThe book of author about walking contains my personal statement through texts and illustrations. It presents walking as a way of meditation and mindfulness. It leads to live in the present and to be attentive to ourselves and our surroundings, especially to the beauties of nature and its changes
Metacarbonatite or marble? — the case of the carbonate, pyroxenite, calcite–apatite rock complex at Borra, Eastern Ghats, India
No full textCarbonatites are often of economic importance, which raises the problem of distinguishing carbonatites from limestones when either are metamorphosed to high-grade marbles. They can be of similar appearance, particularly those from the Proterozoic and Archaean of the Indian Subcontinent. This study also contributes to solving the problem of determining the frequency of alkaline and carbonatitic magmatism during the early history of the Earth.The mineral assemblage of apatite–magnetite–phlogopite–calcite is common to marbles of both carbonatite and limestone origin. If pyrochlore is present that identifies the rock as carbonatite; if anorthite, fassaite, scapolite or spinel then it was formerly a limestone. If these minerals are absent, then trace element analysis can supply the critical Sr and REE data, which are both normally high in carbonatitic rocks and low in former limestones. These distinguishing factors are applied to the metamorphic carbonate, pyroxenite, calcite–apatite rock complex at Borra, Eastern Ghats, India, which has been variously interpreted as formerly a carbonatite and as a limestone. The evidence shows that the Borra rocks are meta-sedimentary.<br/
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