41,366 research outputs found
Null Subjects in Northeast English
No full textThis paper presents data and analysis relating to null subjects in spoken colloquial English.
While English is not a „pro-drop? language (i.e. subjects must usually be overt), a corpus of
speech collected on Tyneside and Wearside in 2007 shows that null subjects are permitted in
finite clauses in certain contexts. This paper analyses these examples and follow-up
questionnaires, and compares the data with the other types of null subject described in the
literature (pro-drop, topic-drop, early null subjects, aphasics? null subjects and „diary-drop?),
ultimately concluding that the colloquial English phenomenon is most closely related to diary-
drop
Null controllability for parabolic operators with interior degeneracy and one-sided control
No full textFor alpha is an element of (0, 2) we study the null controllability of the parabolic operator Pu = u(t) - (vertical bar x vertical bar(alpha)ux)(x) (-1 < x < 1), which degenerates at the interior point x = 0 for locally distributed controls acting only on one side of the origin (that is, on some interval (a, b) with 0 < a < b < 1). Our main results guarantee that P is null controllable if and only if it is weakly degenerate, that is, alpha is an element of (0, 1). (So, in order to steer the system to zero, one needs controls to act on both sides of the point of degeneracy in the strongly degenerate case alpha is an element of [1, 2).) Our approach is based on spectral analysis and the moment method. We also provide numerical evidence to illustrate our theoretical results
Study of the decay mechanism for B+ -> p(p)over-barK(+) and B+ -> p(p)over-bar pi(+)
No full textWe study the characteristics of the low mass p (p) over bar enhancements near threshold in the three-body decays B+ -> p (p) over barK(+) and B+ -> p (p) over bar pi(+). We observe that the proton polar angle distributions in the p (p) over bar helicity frame in the two decays have the opposite polarity, and measure the forward-backward asymmetries as a function of the p mass for the p (p) over barK(+) mode. We also search for the intermediate two-body decays, B+ -> (p) over bar Delta(++) and B+ -> p (Delta) over bar (0), and set upper limits on their branching fractions. These results are obtained from a 414 fb(-1) data sample that contains 449 x 10(6) B (B) over bar events collected near the Gamma(4S) resonance with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. (c) 2007 Elsevier B.V. All rights reserved.IPE
The appearance, motion, and disappearance of three-dimensional magnetic null points
No full textN.A.M. acknowledges support from NASA grants NNX11AB61G, NNX12AB25G, and NNX15AF43G; NASA contract NNM07AB07C; and NSF SHINE grants AGS-1156076 and AGS-1358342 to SAO. C.E.P. acknowledges support from the St Andrews 2013 STFC Consolidated grant.While theoretical models and simulations of magnetic reconnection often assume symmetry such that the magnetic null point when present is co-located with a flow stagnation point, the introduction of asymmetry typically leads to non-ideal flows across the null point. To understand this behavior, we present exact expressions for the motion of three-dimensional linear null points. The most general expression shows that linear null points move in the direction along which the magnetic field and its time derivative are antiparallel. Null point motion in resistive magnetohydrodynamics results from advection by the bulk plasma flow and resistive diffusion of the magnetic field, which allows non-ideal flows across topological boundaries. Null point motion is described intrinsically by parameters evaluated locally; however, global dynamics help set the local conditions at the null point. During a bifurcation of a degenerate null point into a null-null pair or the reverse, the instantaneous velocity of separation or convergence of the null-null pair will typically be infinite along the null space of the Jacobian matrix of the magnetic field, but with finite components in the directions orthogonal to the null space. Not all bifurcating null-null pairs are connected by a separator. Furthermore, except under special circumstances, there will not exist a straight line separator connecting a bifurcating null-null pair. The motion of separators cannot be described using solely local parameters because the identification of a particular field line as a separator may change as a result of non-ideal behavior elsewhere along the field line.Peer reviewe
Measurement of the branching fraction
No full textThe B
0
s
→ J/ψK
0
S
branching fraction is measured in a data sample corresponding to 0.41 fb−1
of integrated luminosity collected with the LHCb detector at the LHC. This channel is sensitive to
the penguin contributions affecting the sin 2β measurement from B
0
→ J/ψK
0
S
. The time-integrated
branching fraction is measured to be B(B
0
s
→ J/ψK
0
S
) = (1.83±0.28)×10−5
. This is the most precise
measurement to date
Incidenza di tumori nella popolazione dell’area Seveso a 20 anni dall’incidente
No full textIntroduzione. Il 10 luglio 1976 a seguito di un incidente in un impianto per la produzione di triclorofenolo si verificò il rilascio di diossina (2,3,7,8-tetraclorodibenzo-p-diossina, TCDD) e la contaminazione di una vasta area a nord di Milano. Sulla base delle misurazioni di TCDD nel suolo l’area venne divisa in tre zone a diversi livelli di contaminazione: A (molto elevato), B (elevato) e R (basso). Successive indagini confermarono la presenza di elevate concentrazioni di TCDD nel sangue degli abitanti, mediamente in buon accordo con la zona. Per valutare gli effetti a lungo termine della TCDD sono tuttora in corso diversi studi epidemiologici. Il principale risultato degli studi di incidenza di tumori (1977-1991) e mortalità (1976-2001) consiste in un eccesso di tumori del sistema linfatico ed ematopoietico nelle zone più contaminate A e B. Vengono presentati i risultati dell’aggiornamento dello studio di incidenza di tumori a tutto il 1996.
Metodi. La coorte degli esposti ha due componenti: coorte fissa, con oltre 37.000 soggetti (zona A: 723; zona B: 4.821; zona R: 31.643) residenti nell’area nel periodo dell’incidente e quindi interessati da una elevata esposizione, sia diretta, per esposizione alla nube tossica, sia indiretta, per via del consumo di alimenti prodotti in loco); coorte dinamica, presumibilmente meno esposta, con circa 8.000 persone immigrate o nate nell’area successivamente, fino al 1986 (zona A: 81; zona B: 1.120; zona R: 6.980). Come popolazione di riferimento è stata scelta la coorte dei soggetti residenti (181.574) o entrati/nati successivamente (51.166) nell’area circostante non contaminata. In totale la popolazione seguita consiste di 278.108 soggetti residenti negli 11 comuni dell’area. Per l’accertamento dei casi di tumore maligno è stato effettuato un incrocio tra l’anagrafe Seveso e i dati anonimi delle schede di dimissione ospedaliera (SDO) relative ai ricoveri con diagnosi di dimissione di tumore, utilizzando le chiavi sesso, residenza, data di nascita. Sono quindi stati estratti dalle cartelle cliniche e inseriti in archivio elettronico i dati clinici utili alla definizione delle seguenti variabili: data di incidenza; natura, sede ed eventuale morfologia delle neoplasie, codificate in modo automatico secondo le classificazioni internazionali delle malattie. E’ stato utilizzato il programma Stata 9 per il calcolo degli anni-persona e, tramite regressione di Poisson, dei rapporti fra tassi (Rate Ratios, RR) e i relativi intervalli di confidenza al 95% (IC95%), per le tre zone inquinate rispetto al riferimento, aggiustati/stratificati per sesso, periodo, età, tempo dalla esposizione.
Risultati. La raccolta e definizione dei dati è in via di completamento. La proporzione di casi con verifica cito-istologica è risultata del 77%, la quota dei casi identificati solo tramite certificato di morte (Death Certificate Only, DCO) dell’11%. Analisi preliminari per i soggetti residenti all’incidente di età fino a 74 anni hanno evidenziato una incidenza di tumori maligni totali non superiore a quella osservata nella zona di riferimento. I tumori del sistema linfatico ed ematopoietico sono risultati in eccesso in zona A (4 casi; RR=1,4; IC95%: 0,5-3,7) e in zona B (30 casi; RR=1,6; IC95%: 1,1-2,3). In zona B è stato registrato anche un aumento di tumori del retto (17 casi, RR=1,8; IC95%: 1,1-3,0) e delle vie biliari (RR=2,2; IC95%: 1,0-5,2). Casi di sarcoma (viscerali e non) sono stati osservati in zona B (3 casi, RR=0,8; IC95%: 0,3-2,6) e zona R (24 casi, RR=1,0; IC95%: 0,6-2,5).
Conclusioni. Nel complesso i risultati dell’analisi di incidenza di tumori a 20 anni dall’incidente confermano, in accordo con lo studio di mortalità, un eccesso per neoplasie del sistema linfatico ed ematopoietico nelle due zone a più elevata contaminazione
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
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
A 2 h periodic variation in the low-mass X-ray binary Ser X-1
No full textSpectroscopy of the low-mass X-ray binary Ser X-1 using the Gran Telescopio Canarias have revealed a ?2 h periodic variability that is present in the three strongest emission lines. We tentatively interpret this variability as due to orbital motion, making it the first indication of the orbital period of Ser X-1. Together with the fact that the emission lines are remarkably narrow, but still resolved, we show that a main-sequence K dwarf together with a canonical 1.4 M? neutron star gives a good description of the system. In this scenario, the most likely place for the emission lines to arise is the accretion disc, instead of a localized region in the binary (such as the irradiated surface or the stream-impact point), and their narrowness is due instead to the low inclination (?10°) of Ser X-1
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