Centre of Mass

Over the last decade, electron transport through quantum dots has attracted considerable attention from the scientific and engineering community. The electronic motion through these structures is strongly modified by single-electron charging and energy level quantization 1,2 . Recently, much effort has been directed toward extending these studies to chemical nanostructures, such as molecules 3-8 , nanocrystals 9-13 , and nanotubes 14-17 . Here we report for the first time the fabrication of single-molecule transistors based on individual C 60 molecules. Transport measurements of single-C 60 transistors provide evidence for coupling between the center-of-mass motion of C 60 and single-electron hopping 18 , a novel conduction mechanism that has not been observed in previous quantum-dot studies. This coupling manifests itself as quantized nano-mechanical oscillations of C 60 against the gold surface. The frequency of this oscillation is determined to be around 1.2 THz, in excellent agreement with a simple theoretical estimate based on van der Waals and electrostatic interactions between C 60 and gold electrodes.

The production of c and b quarks in γγ collisions is studied with the L3 detector at LEP with 410 pb −1 of data, collected at centre-of-mass energies from 189 GeV to 202 GeV. Hadronic final states containing c and b quarks are identified by detecting electrons or muons from their semileptonic decays. The cross sections σ(e + e − → e + e − ccX) and σ(e + e − → e + e − bbX) are measured and compared to nextto-leading order perturbative QCD calculations. The cross section of b production is measured in γγ collisions for the first time. It is in excess of the QCD prediction by a factor of three.

Body segment inertial parameters (BSIPs) are important data in biomechanics. They are usually estimated from predictive equations reported in the literature. However, most of the predictive equations are ambiguously applicable in the conventional 3D segment coordinate systems (SCSs). Also, the predictive equations reported in the literature all include two assumptions: the centre of mass and the proximal and distal endpoints

The cross section for the production of Z boson pairs is measured using the data collected by the L3 detector at LEP in 1999 in e + e − collisions at centre-of-mass energies ranging from 192 GeV up to 202 GeV. Events in all the visible final states are selected, measuring the cross section of this process. The special case of final states containing b quarks is also investigated. All results are in agreement with the Standard Model predictions.

Walking and running, the two basic gaits used by man, are very complex movements. They can, however, be described using two simple models: an inverted pendulum and a spring. Muscles must contract at each step to move the body segments in the proper sequence but the work done is, in part, relieved by the interplay of mechanical energies, potential and kinetic in walking, and elastic in running. This explains why there is an optimal speed of walking (minimal metabolic cost of about 2 J.kg–1·m–1 at about 1.11 m.s–1) and why the cost of running is constant and independent of speed (about 4 J.kg–1.m–1). Historically, the mechanical work of locomotion has been divided into external and internal work. The former is the work done to raise and accelerate the body centre of mass (m) within the environment, the latter is the work done to accelerate the body segments with respect to the centre of m. The total work has been calculated, somewhat arbitrarily, as the sum of the two. While the changes of potential and kinetic energies can be accurately measured, the contribution of the elastic energy cannot easily be assessed, nor can the true work performed by the muscles. Many factors can affect the work of locomotion - the gradient of the terrain, body size (height and body m), and gravity. The partitioning of positive and negative work and their different efficiencies explain why the most economical gradient is about –10% (1.1 J.kg–1.m–1 at 1.3 m.s–1 for walking, and 3.1 J.kg–1.m–1 at between 3 and 4 m·s–1 for running). The mechanics of walking of children, pigmies and dwarfs, in particular the recovery of energy at each step, is not different from that of taller (normal sized) individuals when the speed is expressed in dynamically equivalent terms (Froude number). An extra load, external or internal (obesity) affects internal and external work according to the distribution of the added m. Different gravitational environments determine the optimal speed of walking and the speed of transition from walking to running: at more than 1 g it is easier to walk than to run, and it is the opposite at less than 1 g. Passive aids, such as skis or skates, allow an increase in the speed of progression, but the mechanics of the locomotion cannot be simply described using the models for walking and running because step frequency, the proportion of step duration during which the foot is in contact with the ground, the position of the limbs, the force exerted on the ground and the time of its application are all different.

The energy dependence of the relative production rate of three-jet events is studied in hadronic e+e -annihilation events at centre of mass energies between 22 and 46.7 GeV. Three-jet events are defined by a jet finding algorithm which is closely related to the definition of resolvable jets used in O (ot~) perturbative QCD calculations, where the relative production rate of three-jet events is roughly proportional to the size of the strong coupling strength. The production rates of three-jet events in the data decrease significantly with increasing centre of mass energy. The experimental rates, which are independent of fragmentation model calculations, can be directly compared to theoretically calculated jet production rates and are in good agreement with the QCD expectations of a running coupling strength. The hypothesis of an energy independent coupling constant can be excluded with a significance of four standard deviations.

The four jet topology is analysed in the ALEPH data taken between November1995 and October 1997, at centre-of-mass energies ranging from 130 to 184 GeV. While an unexpected accumulation of events with a dijet mass sum around 105 GeV/c 2 had been observed during the rst run in 1995 at 130/136 GeV, corresponding to an integrated luminosity o f 5.7 pb 1 , no signicant dierences between data and standard model prediction is seen, either in the high energy runs (81.1 pb 1 taken at centre-of-mass energies from 161 to 184 GeV) or in the 7.1 pb 1 recorded during a new short run at 130/136 GeV in 1997. We h a v e found no other explanation for the earlier reported \four jet anomaly" than a statistical uctuation.

This study investigated the influence of fear of falling or postural threat on the control of posture and movement during a voluntary rise to toes task for 12 healthy young adults. Postural threat was modified through alterations to the surface height at which individuals stood (low or high platform) and changes in step restriction (away from or at the edge of the platform) creating four levels of postural threat: LOW AWAY, LOW EDGE, HIGH AWAY and HIGH EDGE. To rise to the toes, an initial postural adjustment must destabilise the body so that it can be moved forward and elevated to a new position of support over the toes. Centre of pressure and centre of mass profiles, as well as tibialis anterior (TA), soleus (SO) and gastrocnemius (GA) muscle activity patterns were used to describe this behaviour. The results showed that the performance of the rise to toes task was significantly modified when positioned at the edge of the high platform. In this situation, the central nervous system reduced the magnitude and rate of the postural adjustments and subsequent voluntary movement. Although the duration of the movement was lengthened for this most threatening condition, the sequencing and relative timing of TA, SO and GA muscle activity was preserved. These changes in rise to toes behaviour were accompanied by evidence of increased physiological arousal and participant reports of decreased confidence, increased anxiety and decreased stability. Evidence of fear of falling effects on anticipatory postural control is clinically relevant as it may explain deficits in this control observed in individuals with balance disorders. For example, individuals with Parkinson’s disease or cerebellar dysfunction demonstrate impaired performance on the rise to toes task as reflected in alterations of both the timing and magnitude of their anticipatory postural adjustments. Our findings suggest alterations in the magnitude of postural adjustments may be magnified by fear of falling while changes in the timing of postural adjustments may reflect underlying pathology.

The first measurement of the charged-particle multiplicity density at midrapidity in Pb-Pb collisions at a center-of-mass energy per nucleon pair ffiffiffiffiffiffiffiffi s NN p ¼ 2:76 TeV is presented. For an event sample corresponding to the most central 5% of the hadronic cross section, the pseudorapidity density of primary charged particles at midrapidity is 1584 AE 4ðstatÞ AE 76ðsystÞ, which corresponds to 8:3 AE 0:4ðsystÞ per participating nucleon pair. This represents an increase of about a factor 1.9 relative to pp collisions at similar collision energies, and about a factor 2.2 to central Au-Au collisions at ffiffiffiffiffiffiffiffi s NN p ¼ 0:2 TeV. This measurement provides the first experimental constraint for models of nucleus-nucleus collisions at LHC energies.

Jet production in deep inelastic scattering for 120 < Q2 < 3600 GeV' has been studied using data from an integrated luminosity of 3.2 pbb' collected with the ZEUS detector at HERA. Jets are identified with the JADE algorithm. A cut on the angular distribution of parton emission in the y*-parton centre-of-mass system minimises the experimental and theoretical uncertainties in the determination of the jet rates. The jet rates, when compared to 0( (Y,=) perturbative QCD calculations, allow a precise determination of czs (Q) in three Q*-intervals. The values are consistent with a running of crys(Q), as expected from QCD. Extrapolating to Q = 1'14~0 yields a,( Mzo) = 0.117 f. 0.005 (stat) ?igi (syst,,,) f 0.007 (sys&,).

A resonance search has been made in the K 0 S p and K 0 Sp invariant-mass spectrum measured with the ZEUS detector at HERA using an integrated luminosity of 121 pb −1 . The search was performed in the central rapidity region of inclusive deep inelastic scattering at an ep centre-of-mass energy of 300-318 GeV for exchanged photon virtuality, Q 2 , above 1 GeV 2 . Recent results from fixed-target experiments give evidence for a narrow baryon resonance decaying to K + n and K 0 S p, interpreted as a pentaquark. The results presented here support the existence of such state, with a mass of 1521.5±1.5(stat.) +2.8 −1.7 (syst.) MeV and a Gaussian width consistent with the experimental resolution of 2 MeV. The signal is visible at high Q 2 and, for Q 2 > 20 GeV 2 , contains 221 ± 48 events. The probability of a similar signal anywhere in the range 1500-1560 MeV arising from fluctuations of the background is below 6 × 10 −5 .

A laboratory study was conducted to examine gait changes associated with aging and the effect of these changes on initiation of slips and frequency of falls utilizing newly defined biomechanical parameters of slips and falls. Twenty-eight participants from two age groups (young and old) walked around a circular track at a comfortable pace wearing a safety harness. A slippery floor surface was placed on the walking track over the force plate at random time intervals without the participants' awareness. Synchronized kinetic and kinematic measurements were obtained on both slippery and non-slippery walking surfaces. The results indicated that older participants' horizontal heel contact velocity was significantly faster, step length was significantly shorter, and transitional acceleration of the whole body centre-of-mass (COM) was significantly slower than younger participants. Older participants' initial friction demand, as measured by required coefficient of friction (RCOF), was not significantly different than their younger counterparts. Additionally, older participants slipped longer and faster, and fell more often than younger participants. A comparison of horizontal heel contact velocity for participants who fell with participants who did not fall indicated that, in general, fallers' horizontal heel contact velocity was faster than non-fallers. However, a comparison of RCOF for participants who fell with participants who did not fall suggested that RCOF was not a totally deterministic factor influencing actual fall events. These findings suggest that gait changes associated with aging (especially higher horizontal heel contact velocity and slower transition of the whole body COM) affect initiation of slip-induced falls.

Motivated by the experimental accessibility of rare B decays in the ongoing and planned experiments, we propose to undertake a model-independent analysis of the inclusive decay rates and distributions in the processes B → X s γ and B → X s ℓ + ℓ − (B = B ± or B 0 d ). We show how measurements of the decay rates and distributions in these processes would allow us to extract the magnitude and sign of the dominant Wilson coefficients of the magnetic moment operator m bsL σ µν b R F µν and the four-fermion operators (s L γ µ b L )(lγ µ ℓ) and (s L γ µ b L )(lγ µ γ 5 ℓ). Non-standard-model effects could thus manifest themselves at low energy in rare B decays through the Wilson coefficient having values distinctly different from their standard-model counterparts. We illustrate this possibility using the examples of the twodoublet Higgs models and the minimal supersymmetric models. The dilepton invariant mass spectrum and the forward-backward asymmetry of ℓ + in the centre-of-mass system of the dilepton pair in the decay B → X s ℓ + ℓ − are also worked out for the standard model and some representative solutions for the other two models.

We report a measurement of the ratios of Wilson coefficients A 9 /A 7 and A 10 /A 7 in B → K * ℓ + ℓ − . The result is obtained from a data sample containing 386 million BB pairs that was collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric energy e + e − collider.

The production of the prompt charm mesons D 0 , D + , D * + , and their antiparticles, was measured with the ALICE detector in Pb-Pb collisions at the LHC, at a centre-of-mass energy √ s NN = 2.76 TeV per nucleon-nucleon collision. The p t -differential production yields in the range 2 < p t < 16 GeV/c at central rapidity, |y| < 0.5, were used to calculate the nuclear modification factor R AA with respect to a proton-proton reference obtained from the cross section measured at √ s = 7 TeV and scaled to √ s = 2.76 TeV. For the three meson species, R AA shows a suppression by a factor 3-4, for transverse momenta larger than 5 GeV/c in the 20% most central collisions. The suppression is reduced for peripheral collisions. * See Appendix A for the list of collaboration members Suppression of high p t D mesons in Pb-Pb collisions at √ s NN = 2.76 TeV 3 Suppression of high p t D mesons in Pb-Pb collisions at √ s NN = 2.76 TeV Suppression of high p t D mesons in Pb-Pb collisions at √ s NN = 2.76 TeV 7 central collisions), aimed at reducing the large combinatorial background.

In a search for the Standard Model Higgs boson, carried out on 212.5 pb −1 of data collected by the L3 detector at the highest LEP centre-of-mass energies, including 116.5 pb −1 above √ s = 206 GeV, an excess of candidates for the process e + e − → Z * → HZ is found for Higgs masses near 114.5 GeV. We present an analysis of our data and the characteristics of our strongest candidates.

Measurements of b hadron production ratios in proton-proton collisions at a center-of-mass energy of 7 TeV with an integrated luminosity of 3 pb À1 are presented. We study the ratios of strange B meson to light B meson production f s =ðf u þ f d Þ and à 0 b baryon to light B meson production f à b =ðf u þ f d Þ as a function of the charmed hadron-muon pair transverse momentum p T and the b hadron pseudorapidity , for p T between 0 and 14 GeV and between 2 and 5. We find that f s =ðf u þ f d Þ is consistent with being independent of p T and , and we determine f s =ðf u þ f d Þ ¼ 0:134 AE 0:004 þ0:011 À0:010 , where the first error is statistical and the second systematic. The corresponding ratio f à b =ðf u þ f d Þ is found to be dependent upon the transverse momentum of the charmed hadron-muon pair, f à b =ðf u þf d Þ¼ð0:404AE0:017ðstatÞAE 0:027ðsystÞAE0:105ðBrÞÞ½1Àð0:031AE0:004ðstatÞAE0:003ðsystÞÞÂp T ðGeVÞ, where Br reflects an absolute scale uncertainty due to the poorly known branching fraction Bðà þ c ! pK À þ Þ. We extract the ratio of strange B meson to light neutral B meson production f s =f d by averaging the result reported here with two previous measurements derived from the relative abundances of " B 0 s ! D þ s À to " B 0 ! D þ K À and " B 0 ! D þ À . We obtain f s =f d ¼ 0:267 þ0:021 À0:020 .

We report on the wettability properties of silicon surfaces, simultaneously structured on the micrometre-scale and the nanometre-scale by femtosecond (fs) laser irradiation to render silicon hydrophobic. By varying the laser fluence, it was possible to control the wetting properties of a silicon surface through a systematic and reproducible variation of the surface roughness. In particular, the silicon-water contact angle could be increased from 66 • to more than 130 • . Such behaviour is described by incomplete liquid penetration within the silicon features, still leaving partially trapped air inside. We also show how controllable design and tailoring of the surface microstructures by wettability gradients can drive the motion of the drop's centre of mass towards a desired direction (even upwards).

Measurements of cross sections of inelastic and diffractive processes in proton-proton collisions at LHC energies were carried out with the ALICE detector. The fractions of diffractive processes in inelastic collisions were determined from a study of gaps in charged particle pseudorapidity distributions: for single diffraction (diffractive mass M X < 200 GeV/c 2 ) σ SD /σ INEL = 0.21 ± 0.03, 0.20 +0.07 −0.08 , and 0.20 +0.04 −0.07 , respectively at centre-of-mass energies

A search for the lightest neutral CP-even and neutral CP-odd Higgs bosons of the Minimal Supersymmetric Standard Model is performed using 216.6 pb −1 of data collected with the L3 detector at LEP at centre-of-mass energies between 203 and 209 GeV. No indication of a signal is found. Including our results from lower centre-of-mass energies, lower limits on the Higgs boson masses are set as a function of tanβ for several scenarios. For tanβ greater than 0.7 they are m h > 84.5 GeV and m A > 86.3 GeV at 95% confidence level.

Multiplicity distributions of charged particles for inelastic, non single-diffractive events in proton-antiproton collisions at a centre of mass energy of 540 GeV are presented for various pseudorapidity (Δη) intervals. The widths of the multiplicity distributions, scaled to their ...

This report summarizes a study of the physics potential of the CLIC e+e- linear collider operating at centre-of-mass energies from 1 TeV to 5 TeV with luminosity of the order of 10^35 cm^-2 s^-1. First, the CLIC collider complex is surveyed, with emphasis on aspects related to its physics capabilities, particularly the luminosity and energy, and also possible polarization, \gamma\gamma and e-e- collisions. The next CLIC Test facility, CTF3, and its R&D programme are also reviewed. We then discuss aspects of experimentation at CLIC, including backgrounds and experimental conditions, and present a conceptual detector design used in the physics analyses, most of which use the nominal CLIC centre-of-mass energy of 3 TeV. CLIC contributions to Higgs physics could include completing the profile of a light Higgs boson by measuring rare decays and reconstructing the Higgs potential, or discovering one or more heavy Higgs bosons, or probing CP violation in the Higgs sector. Turning to physics beyond the Standard Model, CLIC might be able to complete the supersymmetric spectrum and make more precise measurements of sparticles detected previously at the LHC or a lower-energy linear e+e- collider: \gamma\gamma collisions and polarization would be particularly useful for these tasks. CLIC would also have unique capabilities for probing other possible extensions of the Standard Model, such as theories with extra dimensions or new vector resonances, new contact interactions and models with strong WW scattering at high energies. In all the scenarios we have studied, CLIC would provide significant fundamental physics information beyond that available from the LHC and a lower-energy linear e+e- collider, as a result of its unique combination of high energy and experimental precision.

Decays of b hadrons into final states containing a D 0 meson and a muon are used to measure the bb production cross-section in proton-proton collisions at a centre-of-mass energy of 7 TeV at the LHC. In the pseudorapidity interval 2 < η < 6 and integrated over all transverse momenta we find that the average cross-section to produce b-flavoured or b-flavoured hadrons is (75.3±5.4±13.0) µb.

Cross sections for elastic and proton-dissociative photoproduction of J/ψ mesons are measured with the H1 detector in positron-proton collisions at HERA. The data were collected at ep centre-of-mass energies √ s ≈ 318 GeV and √ s ≈ 225 GeV, corresponding to integrated luminosities of L = 130 pb −1 and L = 10.8 pb −1 , respectively. The cross sections are measured as a function of the photon-proton centre-of-mass energy in the range 25 < W γp < 110 GeV. Differential cross sections dσ/dt, where t is the squared fourmomentum transfer at the proton vertex, are measured in the range |t| < 1.2 GeV 2 for the elastic process and |t| < 8 GeV 2 for proton dissociation. The results are compared to other measurements. The W γp and t-dependences are parametrised using phenomenological fits.

Events with a large rapidity gap and total transverse energy greater than 5 GeV have been observed in quasi-real photoproduction at HERA with the ZEUS detector. The distribution of these events as a function of the γp centre of mass energy is consistent with diffractive scattering. For total transverse energies above 12 GeV, the hadronic final states show predominantly a two-jet structure with each jet having a transverse energy greater than 4 GeV. For the two-jet events, little energy flow is found outside the jets. This observation is consistent with the hard scattering of a quasi-real photon with a colourless object in the proton.

The performance of the GROMOS96 parameter set 45A3 developed for aliphatic alkanes is tested on a bilayer of dipalmitoylphosphatidylcholine (DPPC) in water in the liquid-crystalline L(alpha) phase. Variants of the force-field parameter set as well as different sets of simulation conditions or simulation parameter sets are evaluated. In the case of the force-field parameters, the van der Waals constants for the non-bonded interaction of the ester carbonyl carbon and the partial charges and charge group definition of the phosphatidylcholine head group are examined. On the methodological side, different cut-off distances for the non-bonded interactions, use of a reaction-field force due to long-range electrostatic interactions, the frequency of removal of the centre of mass motion and the strength of the coupling of the pressure of the system to the pressure bath are tested. The area per lipid, as a measure of structure, the order parameters of the chain carbons, as a measure of membra...

Within-subject reproducibility of visual brain activation using multislice echo planar functional magnetic resonance imaging (fMRI) was tested. Ten healthy subjects underwent fMRI with visual stimulation on three occasions: two studies in one scanning session (without repositioning); and a third study 1 h to 2 weeks later. Following a three-dimensional matching procedure, activation was measured and compared between sessions on a voxel-by-voxel basis. Data were filtered to full-width-at-half-maximum of 4.0 ؋ 4.0 ؋ 5.0 mm and a conservative Bonferroni-corrected significance threshold was applied to correlation maps. For reproducibility, change in centre of mass of the activated volume, a ratio of the number of pixels and a ratio of the number of overlapping pixels was calculated. Further, reproducibility was tested varying significance thresholds and at different filter widths. Average changes in centre of mass of the activated volume were 2.63 and 3.96 mm between Studies 1 and 2 and 1 and 3, respectively. The reproducibility of the number of activated voxels was 90% and 88% . The ratio of overlapping pixels was 74% between Studies 1 and 2 and 64% between Studies 1 and 3. Varying the significance threshold showed that at a certain range, the overlap reached a maximum, and increasing the filter widths increased reproducibility. It is concluded that fMRI with visual stimulation can be used to measure brain activity with reasonably good reproducibility on a routine clinical system equipped with echo planar imaging. Difficulties remain in separating the contribution of motion, repositioning errors, and true physiological changes.

DELPHI data collected at centre-of-mass energies up to 208 GeV have been analysed to search for charginos, neutralinos and sfermions in the framework of the Minimal Supersymmetric Standard Model (MSSM) with R-parity conservation. No evidence for a signal was found in any of the channels. The results of each search were used to derive upper limits on production cross-sections and masses. In addition, the combined result of all searches excludes regions in the parameter space of the constrained MSSM, leading to limits on the mass of the Lightest Supersymmetric Particle and other supersymmetric particles. All limits are given at 95% confidence level.

The total photoproduction cross section is determined from a measurement of electroproduction with the ZEUS detector at HERA. The Q2 values of the virtual photons are in the range 10 -7< Q2<2×10 -2 GeV 2. The γp total cross section in the γp centre of mass energy range 186-233 GeV is 154 ± 16 (stat.) ± 32 (syst.) μb.

The hadronic final states observed with the ALEPH detector at LEP in \rme^+\rme^- annihilation are analysed using 730 pb-1 of data collected between 91 and 209 GeV in the framework of QCD. In particular event-shape variables and inclusive charged particle ...

The Large Hadron Collider (LHC) project was approved by the CERN Council in December 1994. The machine will provide proton-proton collisions with a centre of mass energy of 14 TeV and an unprecedented luminosity of 10 34 cm -2 s -1 . In order to achieve the design energy within the constraint of the 27 km circumference LEP tunnel, the magnet system must operate in superfluid helium below 2 K, with a dipole field of 8.4 Tesla. In addition, space limitations in the tunnel as well as cost considerations dictate a two-in-one magnet design, where the two rings are incorporated into the same cryostat. The machine will also provide heavy (Pb) ion collisions with a luminosity of 10 27 cm -2 s -1 using the existing CERN ion facility. Space will be kept above the LHC for the eventual reinstallation of components of the LEP machine to provide future e-p collisions if the physics case justifies it.

A measurement of inclusive charged particle distributions in deep inelasticep scattering forγ*p centre-of-mass energies 75WQ 22 from the ZEUS detector at HERA is presented. The differential charged particle rates in theγ*p centre-of-mass system as a function of the scaled longitudinal momentum,x F, and of the transverse momentum,p* t and 〈p* t 2〉, as a function ofx F, W andQ 2 are given. Separate distributions are shown for events with (LRG) and without (NRG) a rapidity gap with respect to the proton direction. The data are compared with results from experiments at lower beam energies, with the naive quark parton model and with parton models including perturbative QCD corrections. The comparison shows the importance of the higher order QCD processes. Significant differences of the inclusive charged particle rates between NRG and LRG events at the sameW are observed. The value of 〈p* t 2〉 for LRG events with a hadronic massM x, which excludes the forward produced baryonic system, is similar to the 〈p* t 2〉 value observed in fixed target experiments atW≈M x.

We h a v e studied hadronic events produced at LEP at centre-of-mass energies of 130 and 136 GeV. Distributions of event shape observables, jet rates, momentum spectra and multiplicities are presented and compared to the predictions of several Monte Carlo models and analytic QCD calculations. From ts of event shape and jet rate distributions to O( 2 s )+NLLA QCD calculations, we determine s (133 GeV)= 0:110 0:005(stat:) 0:009(syst:). W e measure the mean charged particle multiplicity hn ch i = 2 3 : 40 0:45(stat:) 0:47(syst:) and the position 0 of the peak in the p = ln(1=x p ) distribution 0 = 3 : 94 0:05(stat:) 0:11(syst:).

The production and semi-leptonic decay of heavy quarks have been studied in the photoproduction process e + p → e + + dijet + e − + X with the ZEUS detector at HERA using an integrated luminosity of 38.5 pb −1 . Events with photon-proton centre-of-mass energies, W γp , between 134 and 269 GeV and a photon virtuality, Q 2 , less than 1 GeV 2 were selected requiring at least two jets of transverse energy E jet1(2) T

Searches for the Standard Model Higgs boson have been performed in the data collected by the DELPHI experiment at LEP in the year 2000 at centre-ofmass energies between 200 and 209 GeV corresponding to a total integrated luminosity of 224 pb −1 . No evidence for a Higgs signal is observed in the kinematically accessible mass range, and a 95% CL lower mass limit of 114.3 GeV/c 2 is set, to be compared with an expected median limit of 113.5 GeV/c 2 for these data.