Electrophysiological measures can help understand brain function both in healthy individuals and in the context of a disease. Given the amount of information that can be extracted from these measures ...and their frequent use, it is essential to know more about their inherent reliability.
To understand the reliability of electrophysiology measures in healthy individuals. We hypothesized that measures of threshold and latency would be the most reliable and least susceptible to methodological differences between study sites.
Somatosensory evoked potentials from 112 control participants; long-latency reflexes, transcranial magnetic stimulation with resting and active motor thresholds, motor evoked potential latencies, input/output curves, and short-latency sensory afferent inhibition and facilitation from 84 controls were collected at 3 visits over 24 months at 4 Track-On HD study sites. Reliability was assessed using intra-class correlation coefficients for absolute agreement, and the effects of reliability on statistical power are demonstrated for different sample sizes and study designs.
Measures quantifying latencies, thresholds, and evoked responses at high stimulator intensities had the highest reliability, and required the smallest sample sizes to adequately power a study. Very few between-site differences were detected.
Reliability and susceptibility to between-site differences should be evaluated for electrophysiological measures before including them in study designs. Levels of reliability vary substantially across electrophysiological measures, though there are few between-site differences. To address this, reliability should be used in conjunction with theoretical calculations to inform sample size and ensure studies are adequately powered to detect true change in measures of interest.
•Levels of reliability varied substantially between electrophysiological measures.•Latencies, thresholds, and SEPs at high intensities had the highest reliability.•Measures of amplitude rather than area were more reliable.•Few between-site differences suggest usefulness of measures in multi-centre trials.•Reliability and hypothetical statistical power calculations can inform study design.
Particle identification techniques are fundamental tools in nuclear physics experiments. Discriminating particles or nuclei produced in nuclear interactions allows to better understand the underlying ...physics mechanisms. The energy interval of these reactions is very broad, from sub-eV up to TeV. For this reason, many different identification approaches have been developed, often combining two or more observables. This paper reviews several of these techniques with emphasis on the expertise gained within the current nuclear physics scientific program of the Italian Istituto Nazionale di Fisica Nucleare (INFN).
The production rates and the transverse momentum distribution of strange hadrons at mid-rapidity (
y
<
0.5
) are measured in proton-proton collisions at
s
= 13 TeV as a function of the charged ...particle multiplicity, using the ALICE detector at the LHC. The production rates of
K
S
0
,
Λ
,
Ξ
, and
Ω
increase with the multiplicity faster than what is reported for inclusive charged particles. The increase is found to be more pronounced for hadrons with a larger strangeness content. Possible auto-correlations between the charged particles and the strange hadrons are evaluated by measuring the event-activity with charged particle multiplicity estimators covering different pseudorapidity regions. When comparing to lower energy results, the yields of strange hadrons are found to depend only on the mid-rapidity charged particle multiplicity. Several features of the data are reproduced qualitatively by general purpose QCD Monte Carlo models that take into account the effect of densely-packed QCD strings in high multiplicity collisions. However, none of the tested models reproduce the data quantitatively. This work corroborates and extends the ALICE findings on strangeness production in proton-proton collisions at 7 TeV.
This paper presents the measurements of
π
±
,
K
±
,
p
and
p
¯
transverse momentum (
p
T
) spectra as a function of charged-particle multiplicity density in proton–proton (pp) collisions at
s
=
13
TeV
...with the ALICE detector at the LHC. Such study allows us to isolate the center-of-mass energy dependence of light-flavour particle production. The measurements reported here cover a
p
T
range from 0.1 to 20
GeV
/
c
and are done in the rapidity interval
|
y
|
<
0.5
. The
p
T
-differential particle ratios exhibit an evolution with multiplicity, similar to that observed in pp collisions at
s
=
7
TeV
, which is qualitatively described by some of the hydrodynamical and pQCD-inspired models discussed in this paper. Furthermore, the
p
T
-integrated hadron-to-pion yield ratios measured in pp collisions at two different center-of-mass energies are consistent when compared at similar multiplicities. This also extends to strange and multi-strange hadrons, suggesting that, at LHC energies, particle hadrochemistry scales with particle multiplicity the same way under different collision energies and colliding systems.
A
bstract
The inclusive J/
ψ
elliptic (
v
2
) and triangular (
v
3
) flow coefficients measured at forward rapidity (2
.
5
< y <
4) and the
v
2
measured at midrapidity (|
y
|
<
0
.
9) in Pb-Pb ...collisions at
s
NN
= 5
.
02 TeV using the ALICE detector at the LHC are reported. The entire Pb-Pb data sample collected during Run 2 is employed, amounting to an integrated luminosity of 750
μ
b
−
1
at forward rapidity and 93
μ
b
−
1
at midrapidity. The results are obtained using the scalar product method and are reported as a function of transverse momentum
p
T
and collision centrality. At midrapidity, the J/
ψ v
2
is in agreement with the forward rapidity measurement. The centrality averaged results indicate a positive J/
ψ v
3
with a significance of more than 5
σ
at forward rapidity in the
p
T
range 2
< p
T
<
5 GeV/
c
. The forward rapidity
v
2
,
v
3
, and
v
3
/v
2
results at low and intermediate
p
T
(
p
T
≲ 8 GeV/
c
) exhibit a mass hierarchy when compared to pions and D mesons, while converging into a species-independent curve at higher
p
T
. At low and intermediate
p
T
, the results could be interpreted in terms of a later thermalization of charm quarks compared to light quarks, while at high
p
T
, path-length dependent effects seem to dominate. The J/
ψ v
2
measurements are further compared to a microscopic transport model calculation. Using a simplified extension of the quark scaling approach involving both light and charm quark flow components, it is shown that the D-meson
v
n
measurements can be described based on those for charged pions and J/
ψ
flow.
A
bstract
Anisotropic flow coefficients,
v
n
, non-linear flow mode coefficients,
χ
n,mk
, and correlations among different symmetry planes,
ρ
n,mk
are measured in Pb-Pb collisions at
s
NN
= 5
.
02 ...TeV. Results obtained with multi-particle correlations are reported for the transverse momentum interval 0
.
2
< p
T
<
5
.
0 GeV/
c
within the pseudorapidity interval 0
.
4
<
|
η
|
<
0
.
8 as a function of collision centrality. The
v
n
coefficients and
χ
n,mk
and
ρ
n,mk
are presented up to the ninth and seventh harmonic order, respectively. Calculations suggest that the correlations measured in different symmetry planes and the non-linear flow mode coefficients are dependent on the shear and bulk viscosity to entropy ratios of the medium created in heavy-ion collisions. The comparison between these measurements and those at lower energies and calculations from hydrodynamic models places strong constraints on the initial conditions and transport properties of the system.
A
bstract
The jet angularities are a class of jet substructure observables which characterize the angular and momentum distribution of particles within jets. These observables are sensitive to ...momentum scales ranging from perturbative hard scatterings to nonperturbative fragmentation into final-state hadrons. We report measurements of several groomed and ungroomed jet angularities in pp collisions at
s
= 5
.
02 TeV with the ALICE detector. Jets are reconstructed using charged particle tracks at midrapidity (
|η| <
0
.
9). The anti-
k
T
algorithm is used with jet resolution parameters
R
= 0
.
2 and
R
= 0
.
4 for several transverse momentum
p
T
ch
jet
intervals in the 20–100 GeV/
c
range. Using the jet grooming algorithm Soft Drop, the sensitivity to softer, wide-angle processes, as well as the underlying event, can be reduced in a way which is well-controlled in theoretical calculations. We report the ungroomed jet angularities,
λ
α
, and groomed jet angularities,
λ
α
,g
, to investigate the interplay between perturbative and nonperturbative effects at low jet momenta. Various angular exponent parameters
α
= 1, 1.5, 2, and 3 are used to systematically vary the sensitivity of the observable to collinear and soft radiation. Results are compared to analytical predictions at next-to-leading-logarithmic accuracy, which provide a generally good description of the data in the perturbative regime but exhibit discrepancies in the nonperturbative regime. Moreover, these measurements serve as a baseline for future ones in heavy-ion collisions by providing new insight into the interplay between perturbative and nonperturbative effects in the angular and momentum substructure of jets. They supply crucial guidance on the selection of jet resolution parameter, jet transverse momentum, and angular scaling variable for jet quenching studies.
the influence of pulse width, pulse waveform and current direction on transcranial magnetic stimulation (TMS) outcomes is of critical importance. However, their effects have only been investigated ...indirectly with motor-evoked potentials (MEP). By combining TMS and EEG it is possible to examine how these factors affect evoked activity from the cortex and compare that with the effects on MEP.
we used a new controllable TMS device (cTMS) to vary systematically pulse width, pulse waveform and current direction and explore their effects on global and local TMS-evoked EEG response.
In 19 healthy volunteers we measured (1) resting motor threshold (RMT) as an estimate of corticospinal excitability; (2) global mean field power (GMFP) as an estimate of global cortical excitability; and (3) local mean field power (LMFP) as an estimate of local cortical excitability.
RMT was lower with monophasic posterior-to-anterior (PA) pulses that have a longer pulse width (p < 0.001). After adjusting for the individual motor threshold of each pulse type we found that (a) GMFP was higher with monophasic pulses (p < 0.001); (b) LMFP was higher with longer pulse width (p = 0.015); (c) early TEP polarity was modulated depending on the current direction (p = 0.01).
Despite normalizing stimulus intensity to RMT, we found that local and global responses to TMS vary depending on pulse parameters. Since EEG responses can vary independently of the MEP, titrating parameters of TMS in relation to MEP threshold is not a useful way of ensuring that a constant set of neurons is activated within a cortical area.
•We explored the cortical effects of TMS pulse width, waveform and current direction.•We used for the first time a novel controllable TMS device in combination with EEG.•Local and global responses to TMS vary according to pulse width and waveform.•Early TEP polarity was modulated depending on the current direction.•Pulse parameters influence “what” is stimulated and “where” TMS is effective.
A
bstract
The production of J
/ψ
is measured at midrapidity (
|y| <
0
.
9) in proton-proton collisions at
s
= 5
.
02 and 13 TeV, through the dielectron decay channel, using the ALICE detector at the ...Large Hadron Collider. The data sets used for the analyses correspond to integrated luminosities of
L
int
= 19.4
±
0.4 nb
−
1
and
L
int
= 32.2
±
0.5 nb
−
1
at
s
= 5
.
02 and 13 TeV, respectively. The fraction of non-prompt J
/ψ
mesons, i.e. those originating from the decay of beauty hadrons, is measured down to a transverse momentum
p
T
= 2 GeV
/c
(1 GeV
/c
) at
s
= 5
.
02 TeV (13 TeV). The
p
T
and rapidity (
y
) differential cross sections, as well as the corresponding values integrated over
p
T
and
y
, are carried out separately for prompt and non-prompt J
/ψ
mesons. The results are compared with measurements from other experiments and theoretical calculations based on quantum chromodynamics (QCD). The shapes of the
p
T
and
y
distributions of beauty quarks predicted by state-of-the-art perturbative QCD models are used to extrapolate an estimate of the
b
b
¯
pair cross section at midrapidity and in the total phase space. The total
b
b
¯
cross sections are found to be
σ
b
b
¯
= 541
±
45 (stat
.
)
±
69
syst
.
−
12
+
10
(extr
.
)
μ
b and
σ
b
b
¯
= 218
±
37 (stat
.
)
±
31
syst
.
−
9.1
+
8.2
(extr
.
)
μ
b at
s
= 13 and 5.02 TeV, respectively. The value obtained from the combination of ALICE and LHCb measurements in pp collisions at
s
= 13 TeV is also provided.
This article reports on the inclusive production cross section of several quarkonium states,
J
/
ψ
,
ψ
(
2
S
)
,
Υ
(
1
S
)
,
Υ
(
2
S
)
, and
Υ
(
3
S
)
, measured with the ALICE detector at the LHC, ...in pp collisions at
s
=
5.02
TeV. The analysis is performed in the dimuon decay channel at forward rapidity (
2.5
<
y
<
4
). The integrated cross sections and transverse-momentum (
p
T
) and rapidity (
y
) differential cross sections for
J
/
ψ
,
ψ
(
2
S
)
,
Υ
(
1
S
)
, and the
ψ
(
2
S
)
-to-
J
/
ψ
cross section ratios are presented. The integrated cross sections, assuming unpolarized quarkonia, are:
σ
J
/
ψ
(
p
T
<
20
GeV/c) = 5.88 ± 0.03 ± 0.34
μ
b,
σ
ψ
(
2
S
)
(
p
T
<
12
GeV/c) = 0.87 ± 0.06 ± 0.10
μ
b,
σ
Υ
(
1
S
)
(
p
T
<
15
GeV/c) = 45.5 ± 3.9 ± 3.5 nb,
σ
Υ
(
2
S
)
(
p
T
<
15
GeV/c) = 22.4 ± 3.2 ± 2.7 nb, and
σ
Υ
(
3
S
)
(
p
T
<
15
GeV/c) = 4.9 ± 2.2 ± 1.0 nb, where the first (second) uncertainty is the statistical (systematic) one. For the first time, the cross sections of the three
Υ
states, as well as the
ψ
(
2
S
)
one as a function of
p
T
and
y
, are measured at
s
=
5.02
TeV at forward rapidity. These measurements also significantly extend the
J
/
ψ
p
T
reach and supersede previously published results. A comparison with ALICE measurements in pp collisions at
s
=
2.76
, 7, 8, and 13 TeV is presented and the energy dependence of quarkonium production cross sections is discussed. Finally, the results are compared with the predictions from several production models.
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