2,055 research outputs found
Hadron Spectroscopy with COMPASS at CERN
The aim of the COMPASS hadron programme is to study the light-quark hadron
spectrum, and in particular, to search for evidence of hybrids and glueballs.
COMPASS is a fixed-target experiment at the CERN SPS and features a two-stage
spectrometer with high momentum resolution, large acceptance, particle
identification and calorimetry. A short pilot run in 2004 resulted in the
observation of a spin-exotic state with consistent with the
debated . In addition, Coulomb production at low momentum transfer
data provide a test of Chiral Perturbation Theory. During 2008 and 2009, a
world leading data set was collected with hadron beam which is currently being
analysed. The large statistics allows for a thorough decomposition of the data
into partial waves. The COMPASS hadron data span over a broad range of channels
and shed light on several different aspects of QCD.Comment: 4 pages, 5 figure
Convergent Validity of a Consumer-Grade Accelerometer with a Research-Grade Pedometer in a Physical Education Setting
The cost of activity monitors has substantially reduced in recent years, making them more feasible for use in physical education programs. This study examined the convergent validity of the consumer-grade Movband activity monitor with the research-grade NL-2000 pedometer. The NL-2000 was chosen as the criterion unit because it is unaffected by BMI, pedometer tilt, or waist circumference, and has been recommended for use in research [1]. One hundred and eleven elementary school aged children (53 boys, 58 girls; 9.2 ± 0.7 yr.) from three physical education classes wore an NL-2000 on their right hip and a Movband on each wrist during a 30 minute class in which participants walked or ran on a hiking trail. A repeated measures ANOVA of mean steps indicated a significant difference (p< .001) between the NL-2000 (2411.74 ± 514.87) and the Movband worn on either wrist (left= 1554.33 ± 340.81, right= 1532.26 ± 329.76). Pearson product-moment correlations indicated that NL-2000 steps and Moves were significantly and positively correlated (p< .001; left= .79, right= .85). The correlation coefficient between left and right wrists was .87. In general, the Movband can provide reasonable estimates of physical activity for physical education teachers
Haemoglobin and size dependent constraints on swimbladder inflation in fish larvae
In developmental studies of fish species (especially physostomians) it could be demonstrated,
that the lack of haemoglobin during larval and juvenile stages is a relatively common phenomenon.
Generally it is linked with body translucency. In representatives of the families Galaxiidae,
Osmeridae and Clupeidae, partly reared, partly observed immediately after being caught in the wild, it
turned out, that this condition coincides with a considerable delay in swimbladder inflation. To determine
the moment of its first inflation, larvae placed in a hermetic chamber were observed under a
dissecting microscope. While lowering the pressure, the expanding swimbladder showed whether or
not its content is really gaseous. The reason postulated to be responsible for the delayed inflation is
that larvae lacking haemoglobin do not have the possibility of oxygen transport to their buoyancy
organ by means of the blood. Apart of this, capillarity force calculations and body force estimations
show that with decreasing size the constraints linked with surface tension increase overproportionally.
While in larger sized larvae like trout we could demonstrate inflation by swallowing air, in species with
small larvae this was not the case. Below a certain size, even in physostomians, the ductus pneumaticus
is no alternative to the blood pathway for swimbladder inflation
Pressure Effect and Specific Heat of RBa2Cu3Ox at Distinct Charge Carrier Concentrations: Possible Influence of Stripes
In YBa2Cu3Ox, distinct features are found in the pressure dependence of the
transition temperature, dTc/dp, and in DeltaCp*Tc, where DeltaCp is the jump in
the specific heat at Tc: dTc/dp becomes zero when DeltaCp*Tc is maximal,
whereas dTc/dp has a peak at lower oxygen contents where DeltaCp*Tc vanishes.
Substituting Nd for Y and doping with Ca leads to a shift of these specific
oxygen contents, since oxygen order and hole doping by Ca influences the hole
content nh in the CuO2 planes. Calculating nh from the parabolic Tc(nh)
behavior, the features coalesce for all samples at nh=0.11 and nh=0.175,
irrespective of substitution and doping. Hence, this behavior seems to reflect
an intrinsic property of the CuO2 planes. Analyzing our results we obtain
different mechanisms in three doping regions: Tc changes in the optimally doped
and overdoped region are mainly caused by charge transfer. In the slightly
underdoped region an increasing contribution to dTc/dp is obtained when well
ordered CuO chain fragments serve as pinning centers for stripes. This behavior
is supported by our results on Zn doped NdBa2Cu3Ox and is responsible for the
well known dTc/dp peak observed in YBa2Cu3Ox at x=6.7. Going to a hole content
below nh=0.11 our results point to a crossover from an underdoped
superconductor to a doped antiferromagnet, changing completely the physics of
these materials.Comment: 6 pages, 5 figures Proccedings of the 'Stripes 2000' Conference, Rome
(2000
Importance of In-Plane Anisotropy in the Quasi Two-Dimensional Antiferromagnet BaNiVO
The phase diagram of the quasi two-dimensional antiferromagnet
BaNiVO is studied by specific heat, thermal expansion,
magnetostriction, and magnetization for magnetic fields applied perpendicular
to . At T, a crossover to a high-field state,
where increases linearly, arises from a competition of intrinsic and
field-induced in-plane anisotropies. The pressure dependences of and
are interpreted using the picture of a pressure-induced in-plane
anisotropy. Even at zero field and ambient pressure, in-plane anisotropy cannot
be neglected, which implies deviations from pure
Berezinskii-Kosterlitz-Thouless behavior.Comment: 4 pages, 4 figure
Magnetic and structural quantum phase transitions in CeCu6-xAux are independent
The heavy-fermion compound CeCuAu has become a model system for
unconventional magnetic quantum criticality. For small Au concentrations , the compound undergoes a structural transition from
orthorhombic to monoclinic crystal symmetry at a temperature with
for . Antiferromagnetic order sets in
close to . To shed light on the interplay between quantum
critical magnetic and structural fluctuations we performed neutron-scattering
and thermodynamic measurements on samples with . The
resulting phase diagram shows that the antiferromagnetic and monoclinic phase
coexist in a tiny Au concentration range between and . The
application of hydrostatic and chemical pressure allows to clearly separate the
transitions from each other and to explore a possible effect of the structural
transition on the magnetic quantum critical behavior. Our measurements
demonstrate that at low temperatures the unconventional quantum criticality
exclusively arises from magnetic fluctuations and is not affected by the
monoclinic distortion.Comment: 5 pages, 3 figure
On Excess Compensation Earned by Underwriters in Firm Commitment Initial Public Offerings of Common Stock: An Empirical Analysis
This paper examines compensation for the underwriting activity in firm commitment initial public offerings (IPOs) of common stock in the U.S. When compensation for origination, management and marketing efforts are excluded from total underwriter compensation, we find that the portion of the total compensation assigned for the underwriting activity itself exceeds theoretical compensation only for issues that sell out very quickly. We interpret this finding as empirical evidence supporting the incentive for underwriters to underprice IPOs. Finally, we find excess compensation to underwriters is positively related to the riskiness of the IPO and negatively related to the degree of competition among investment bankers and the size of the IPO
Magnetic properties of single-crystalline CeCuGa3
The magnetic behavior of single-crystalline CeCuGa3 has been investigated.
The compound forms in a tetragonal BaAl4-type structure consisting of
rare-earth planes separated by Cu-Ga layers. If the Cu-Ga site disorder is
reduced, CeCuGa3 adopts the related, likewise tetragonal BaNiSn3-type
structure, in which the Ce ion are surrounded by different Cu and Ga layers and
the inversion symmetry is lost. In the literature conflicting reports about the
magnetic order of CeCuGa3 have been published. Single crystals with the
centrosymmetric structure variant exhibit ferromagnetic order below approx. 4 K
with a strong planar anisotropy. The magnetic behavior above the transition
temperature can be well understood by the crystal-field splitting of the 4f
Hund's rule ground-state multiplet of the Ce ions
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