The first measurement of lepton-jet momentum imbalance and azimuthal correlation in lepton-proton scattering at high momentum transfer is presented. These data, taken with the H1 detector at HERA, ...are corrected for detector effects using an unbinned machine learning algorithm (multifold), which considers eight observables simultaneously in this first application. The unfolded cross sections are compared with calculations performed within the context of collinear or transverse-momentum-dependent factorization in quantum chromodynamics as well as Monte Carlo event generators.
Résumé Introduction Avec l’augmentation du nombre d’internes en formation, la neurochirurgie française est en pleine mutation démographique. L’objectif de cette étude était de dresser un état des ...lieux des conditions de travail et des perspectives des jeunes neurochirurgiens français. Méthode Une enquête informatisée a été adressée à une liste d’internes et jeunes seniors (219 adresses mail obtenue lors de réunions d’enseignement). Le questionnaire comportait des questions sur les perspectives de carrière, la quantité de travail, le salaire, l’ambiance, la qualité de vie, l’encadrement et le travail universitaire. Résultats Au total, 78 réponses ont été obtenues entre janvier et mars 2014. Cinquante-six pour cent des jeunes seniors ont eu des difficultés à obtenir un post-internat mais en sont satisfaits à 78 %. Les seniors étaient plus nombreux à envisager une carrière libérale que les internes. Les jeunes neurochirurgiens semblaient inquiets vis-à-vis de leurs postes futurs et 33 % des sujets avaient un plan de carrière différent de leurs aspirations initiales. Le temps de travail hebdomadaire moyen de 76,8 h était jugé excessif. Le repos de sécurité était absent ou incomplet dans 91 % des cas. Par ailleurs, 81 % des sujets trouvaient leur salaire insuffisant. L’ambiance de travail était globalement bien perçue (3,7/5), de même que la qualité de vie (3,2/5). L’encadrement théorique était jugé insatisfaisant (2,43/5) de même que le temps de travail universitaire de 1,58 demi-journées mensuelle. En revanche, l’encadrement pratique était très bien perçu (3,63/5). Conclusion Ce travail apporte des éléments d’orientation pour les réformes futures, il devra être réitéré pour en évaluer l’efficacité.
The chemical composition and structure of humic substances were established based on spectroscopic studies (EDXS, SRATR FTIR, and
13
C NMR). Humic acids were isolated from different matrices such as ...soils, compost, lignite, and commercial lignohumate. The btained results showed the highest content of aromatic groups in lignite and humic acids of Chernozem. The aromaticity degree (a) calculated from
13
C NMR spectroscopy data decreased in the following order: lignite > Chernozems > lignohumate > Luvisols > compost > Cambisols. Infrared spectroscopy detected bands indicative of aliphatic groups (C–H at 2925 cm
−1
); aromatic groups (C=C at 1620 cm
−1
); phenolic groups (at 1404–1419 cm
−1
); and carboxyl and carbonyl groups (at 1225–1223 cm
−1
) in all studied humic acid samples. The main differences were found in the fingerprint region of 1700–1000 cm
−1
. The reactivity of humic acids given by the O/R ratio showed that the highest amount of n-alkyl groups were in the lignohumate samples. EDX spectroscopy indicated elements occurring in situ. Soil humic acids contained Fe, Cu, Zn, Ti, Ca, K, S, P, Si, and Br.
Streaming rendering, e.g., rendering in the cloud and streaming via a mobile connection, suffers from increased latency and unreliable connections. High quality framerate upsampling can hide these ...issues, especially when capturing shading into an atlas and transmitting it alongside geometric information. The captured shading information must consider triangle footprints and temporal stability to ensure efficient video encoding. Previous approaches only consider either temporal stability or sample distributions, but none focuses on both. With SnakeBinning, we present an efficient triangle packing approach that adjusts sample distributions and caters for temporal coherence. Using a multi‐dimensional binning approach, we enforce tight packing among triangles while creating optimal sample distributions. Our binning is built on top of hardware supported real‐time rendering where bins are mapped to individual pixels in a virtual framebuffer. Fragment shader interlock and atomic operations enforce global ordering of triangles within each bin, and thus temporal coherence according to the primitive order is achieved. Resampling the bin distribution guarantees high occupancy among all bins and a dense atlas packing. Shading samples are directly captured into the atlas using a rasterization pass, adjusting samples for perspective effects and creating a tight packing. Comparison to previous atlas packing approaches shows that our approach is faster than previous work and achieves the best sample distributions while maintaining temporal coherence. In this way, SnakeBinning achieves the highest rendering quality under equal atlas memory requirements. At the same time, its temporal coherence ensures that we require equal or less bandwidth than previous state‐of‐the‐art. As SnakeBinning outperforms previous approach in all relevant aspects, it is the preferred choice for texture‐based streaming rendering.
Tessellated Shading Streaming Hladky, J.; Seidel, H. P.; Steinberger, M.
Computer graphics forum,
July 2019, 2019-07-00, 20190701, Letnik:
38, Številka:
4
Journal Article
Recenzirano
Presenting high‐fidelity 3D content on compact portable devices with low computational power is challenging. Smartphones, tablets and head‐mounted displays (HMDs) suffer from thermal and battery‐life ...constraints and thus cannot match the render quality of desktop PCs and laptops. Streaming rendering enables to show high‐quality content but can suffer from potentially high latency. We propose an approach to efficiently capture shading samples in object space and packing them into a texture. Streaming this texture to the client, we support temporal frame up‐sampling with high fidelity, low latency and high mobility. We introduce two novel sample distribution strategies and a novel triangle representation in the shading atlas space. Since such a system requires dynamic parallelism, we propose an implementation exploiting the power of hardware‐accelerated tessellation stages. Our approach allows fast de‐coding and rendering of extrapolated views on a client device by using hardware‐accelerated interpolation between shading samples and a set of potentially visible geometry. A comparison to existing shading methods shows that our sample distributions allow better client shading quality than previous atlas streaming approaches and outperforms image‐based methods in all relevant aspects.
Charged particle multiplicity distributions in positron-proton deep inelastic scattering at a centre-of-mass energy
s
=
319
GeV are measured. The data are collected with the H1 detector at HERA ...corresponding to an integrated luminosity of 136 pb
-
1
. Charged particle multiplicities are measured as a function of photon virtuality
Q
2
, inelasticity
y
and pseudorapidity
η
in the laboratory and the hadronic centre-of-mass frames. Predictions from different Monte Carlo models are compared to the data. The first and second moments of the multiplicity distributions are determined and the KNO scaling behaviour is investigated. The multiplicity distributions as a function of
Q
2
and the Bjorken variable
x
bj
are converted to the hadron entropy
S
hadron
, and predictions from a quantum entanglement model are tested.
The strong coupling constant
α
s
is determined from inclusive jet and dijet cross sections in neutral-current deep-inelastic
ep
scattering (DIS) measured at HERA by the H1 collaboration using ...next-to-next-to-leading order (NNLO) QCD predictions. The dependence of the NNLO predictions and of the resulting value of
α
s
(
m
Z
)
at the
Z
-boson mass
m
Z
are studied as a function of the choice of the renormalisation and factorisation scales. Using inclusive jet and dijet data together, the strong coupling constant is determined to be
α
s
(
m
Z
)
=
0.1157
(
20
)
exp
(
29
)
th
. Complementary,
α
s
(
m
Z
)
is determined together with parton distribution functions of the proton (PDFs) from jet and inclusive DIS data measured by the H1 experiment. The value
α
s
(
m
Z
)
=
0.1142
(
28
)
tot
obtained is consistent with the determination from jet data alone. The impact of the jet data on the PDFs is studied. The running of the strong coupling is tested at different values of the renormalisation scale and the results are found to be in agreement with expectations.
The H1 Collaboration at HERA reports the first measurement of groomed event shape observables in deep inelastic electron-proton scattering (DIS) at
s
=
319
GeV, using data recorded between the years ...2003 and 2007 with an integrated luminosity of 351
pb
-
1
. Event shapes provide incisive probes of perturbative and non-perturbative QCD. Grooming techniques have been used for jet measurements in hadronic collisions; this paper presents the first application of grooming to DIS data. The analysis is carried out in the Breit frame, utilizing the novel Centauro jet clustering algorithm that is designed for DIS event topologies. Events are required to have squared momentum-transfer
Q
2
>
150
GeV
2
and inelasticity
0.2
<
y
<
0.7
. We report measurements of the production cross section of groomed event 1-jettiness and groomed invariant mass for several choices of grooming parameter. Monte Carlo model calculations and analytic calculations based on Soft Collinear Effective Theory are compared to the measurements.
The H1 Collaboration reports the first measurement of the 1-jettiness event shape observable
τ
1
b
in neutral-current deep-inelastic electron-proton scattering (DIS). The observable
τ
1
b
is ...equivalent to a thrust observable defined in the Breit frame. The data sample was collected at the HERA
ep
collider in the years 2003–2007 with center-of-mass energy of
s
=
319
GeV
, corresponding to an integrated luminosity of 351.1
pb
-
1
. Triple differential cross sections are provided as a function of
τ
1
b
, event virtuality
Q
2
, and inelasticity
y
, in the kinematic region
Q
2
>
150
GeV
2
. Single differential cross sections are provided as a function of
τ
1
b
in a limited kinematic range. Double differential cross sections are measured, in contrast, integrated over
τ
1
b
and represent the inclusive neutral-current DIS cross section measured as a function of
Q
2
and
y
. The data are compared to a variety of predictions and include long-standing and more recent Monte Carlo event generators, predictions in fixed-order perturbative QCD where calculations up to
O
(
α
s
3
)
are available for
τ
1
b
or inclusive DIS, and resummed predictions at next-to-leading logarithmic accuracy matched to fixed order predictions at
O
(
α
s
2
)
. These comparisons reveal sensitivity of the 1-jettiness observable to QCD parton shower and resummation effects, as well as the modeling of hadronization and fragmentation. Within their range of validity, the fixed-order predictions provide a good description of the data. Monte Carlo event generators are predictive over the full measured range and hence their underlying models and parameters can be constrained by comparing to the presented data.
The Breit frame provides a natural frame to analyze lepton–proton scattering events. In this reference frame, the parton model hard interactions between a quark and an exchanged boson defines the ...coordinate system such that the struck quark is back-scattered along the virtual photon momentum direction. In Quantum Chromodynamics (QCD), higher order perturbative or non-perturbative effects can change this picture drastically. As Bjorken-
x
decreases below one half, a rather peculiar event signature is predicted with increasing probability, where no radiation is present in one of the two Breit-frame hemispheres and all emissions are to be found in the other hemisphere. At higher orders in
α
s
or in the presence of soft QCD effects, predictions of the rate of these events are far from trivial, and that motivates measurements with real data. We report on the first observation of the empty current hemisphere events in electron–proton collisions at the HERA collider using data recorded with the H1 detector at a center-of-mass energy of 319 GeV. The fraction of inclusive neutral-current DIS events with an empty hemisphere is found to be
0.0112
±
3.9
%
stat
±
4.5
%
syst
±
1.6
%
mod
in the selected kinematic region of
150
<
Q
2
<
1500
GeV
2
and inelasticity
0.14
<
y
<
0.7
. The data sample corresponds to an integrated luminosity of 351.1 pb
-
1
, sufficient to enable differential cross section measurements of these events. The results show an enhanced discriminating power at lower Bjorken-
x
among different Monte Carlo event generator predictions.
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