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We study the beam-energy and system-size dependence of \phi meson production (using the hadronic decay mode \phi -- K+K-) by comparing the new results from Cu+Cu collisions and previously reported Au+Au collisions at \sqrt{s_NN} = 62.4 and 200 GeV measured in the STAR experiment at RHIC. Data presented are from mid-rapidity (|y|<0.5) for 0.4 < pT < 5 GeV/c. At a given beam energy, the transverse momentum distributions for \phi mesons are observed to be similar in yield and shape for Cu+Cu and Au+Au colliding systems with similar average numbers of participating nucleons. The \phi meson yields in nucleus-nucleus collisions, normalised by the average number of participating nucleons, are found to be enhanced relative to those from p+p collisions with a different trend compared to strange baryons. The enhancement for \phi mesons is observed to be higher at \sqrt{s_NN} = 200 GeV compared to 62.4 GeV. These observations for the produced \phi(s\bar{s}) mesons clearly suggest that, at these collision energies, the source of enhancement of strange hadrons is related to the formation of a dense partonic medium in high energy nucleus-nucleus collisions and cannot be alone due to canonical suppression of their production in smaller systems.
The STAR Collaboration at the Relativistic Heavy Ion Collider presents measurements of 𝐽/𝜓→𝑒+𝑒− at midrapidity and high transverse momentum (𝑝𝑇>5 GeV/𝑐) in 𝑝+𝑝 and central Cu+Cu collisions at √𝑠𝑁𝑁=200 GeV. The inclusive 𝐽/𝜓 production cross section for Cu+Cu collisions is found to be consistent at high 𝑝𝑇 with the binary collision-scaled cross section for 𝑝+𝑝 collisions. At a confidence level of 97%, this is in contrast to a suppression of 𝐽/𝜓 production observed at lower 𝑝𝑇. Azimuthal correlations of 𝐽/𝜓 with charged hadrons in 𝑝+𝑝 collisions provide an estimate of the contribution of 𝐵-hadron decays to 𝐽/𝜓 production of 13%±5%.
Cloud microphysical processes involving the ice phase in tropospheric clouds are among the major uncertainties in cloud formation, weather and General Circulation Models (GCMs). The simultaneous detection of aerosol particles, liquid droplets, and ice crystals, especially in the small cloud-particle size range below 50 µm, remains challenging in mixed phase, often unstable ice-water phase environments. The Cloud Aerosol Spectrometer with Polarisation (CASPOL) is an airborne instrument that has the ability to detect such small cloud particles and measure their effects on the backscatter polarisation state. Here we operate the versatile Cosmics-Leaving- OUtdoor-Droplets (CLOUD) chamber facility at the European Organisation for Nuclear Research (CERN) to produce controlled mixed phase and other clouds by adiabatic expansions in an ultraclean environment, and use the CASPOL to discriminate between different aerosols, water and ice particles. In this paper, optical property measurements of mixed phase clouds and viscous Secondary Organic Aerosol (SOA) are presented. We report observations of significant liquid – viscous SOA particle polarisation transitions under dry conditions using CASPOL. Cluster analysis techniques were subsequently used to classify different types of particles according to their polarisation ratios during phase transition. A classification map is presented for water droplets, organic aerosol (e.g., SOA and oxalic acid), crystalline substances such as ammonium sulphate, and volcanic ash. Finally, we discuss the benefits and limitations of this classi- fication approach for atmospherically relevant concentration and mixtures with respect to the CLOUD 8–9 campaigns and its potential contribution to Tropical Troposphere Layer (TTL) analysis.
Cloud microphysical processes involving the ice phase in tropospheric clouds are among the major uncertainties in cloud formation, weather, and general circulation models. The detection of aerosol particles, liquid droplets, and ice crystals, especially in the small cloud particle-size range below 50 μm, remains challenging in mixed phase, often unstable environments. The Cloud Aerosol Spectrometer with Polarization (CASPOL) is an airborne instrument that has the ability to detect such small cloud particles and measure the variability in polarization state of their backscattered light. Here we operate the versatile Cosmics Leaving OUtdoor Droplets (CLOUD) chamber facility at the European Organization for Nuclear Research (CERN) to produce controlled mixed phase and other clouds by adiabatic expansions in an ultraclean environment, and use the CASPOL to discriminate between different aerosols, water, and ice particles. In this paper, optical property measurements of mixed-phase clouds and viscous secondary organic aerosol (SOA) are presented. We report observations of significant liquid–viscous SOA particle polarization transitions under dry conditions using CASPOL. Cluster analysis techniques were subsequently used to classify different types of particles according to their polarization ratios during phase transition. A classification map is presented for water droplets, organic aerosol (e.g., SOA and oxalic acid), crystalline substances such as ammonium sulfate, and volcanic ash. Finally, we discuss the benefits and limitations of this classification approach for atmospherically relevant concentrations and mixtures with respect to the CLOUD 8–9 campaigns and its potential contribution to tropical troposphere layer analysis.
Two-particle correlation functions of negative hadrons over wide phase space, and transverse mass spectra of negative hadrons and deuterons near mid-rapidity have been measured in central Pb+Pb collisions at 158 GeV per nucleon by the NA49 experiment at the CERN SPS. A novel Coulomb correction procedure for the negative two-particle correlations is employed making use of the measured oppositely charged particle correlation. Within an expanding source scenario these results are used to extract the dynamic characteristics of the hadronic source, resolving the ambiguities between the temperature and transverse expansion velocity of the source, that are unavoidable when single and two particle spectra are analysed separately. The source shape, the total duration of the source expansion, the duration of particle emission, the freeze-out temperature and the longitudinal and transverse expansion velocities are deduced.
We report measurements of Xi and Xi-bar hyperon absolute yields as a function of rapidity in 158 GeV/c Pb+Pb collisions. At midrapidity, dN/dy = 2.29 +/- 0.12 for Xi, and 0.52 +/- 0.05 for Xi-bar, leading to the ratio of Xi-bar/Xi = 0.23 +/- 0.03. Inverse slope parameters fitted to the measured transverse mass spectra are of the order of 300 MeV near mid-rapidity. The estimated total yield of Xi particles in Pb+Pb central interactions amounts to 7.4 +/- 1.0 per collision. Comparison to Xi production in properly scaled p+p reactions at the same energy reveals a dramatic enhancement (about one order of magnitude) of Xi production in Pb+Pb central collisions over elementary hadron interactions.
The directed and elliptic flow of protons and charged pions has been observed from the semi-central collisions of a 158 GeV/nucleon Pb beam with a Pb target. The rapidity and transverse momentum dependence of the flow has been measured. The directed flow of the pions is opposite to that of the protons but both exhibit negative flow at low pt. The elliptic flow of both is fairly independent of rapidity but rises with pt. PACS numbers: 25.75.-q, 25.75.Ld
The large acceptance TPCs of the NA49 spectrometer allow for a systematic multidimensional study of two-particle correlations in different part of phase space. Results from Bertsch-Pratt and Yano-Koonin-Podgoretskii parametrizations are presented differentially in transverse pair momentum and pair rapidity. These studies give an insight into the dynamical space-time evolution of relativistic Pb+Pb collisions, which is dominated by longitudinal expansion.
The formation of secondary particles in the atmosphere accounts for more than half of global cloud condensation nuclei. Experiments at the CERN CLOUD (Cosmics Leaving OUtdoor Droplets) chamber have underlined the importance of ions for new particle formation, but quantifying their effect in the atmosphere remains challenging. By using a novel instrument setup consisting of two nano-particle counters, one of them equipped with an ion filter, we were able to further investigate the ion-related mechanisms of new particle formation. In autumn 2015, we carried out experiments at CLOUD on four systems of different chemical compositions involving monoterpenes, sulfuric acid, nitrogen oxides, and ammonia. We measured the influence of ions on the nucleation rates under precisely controlled and atmospherically relevant conditions. Our results indicate that ions enhance the nucleation process when the charge is necessary to stabilize newly formed clusters, i.e. in conditions where neutral clusters are unstable. For charged clusters that were formed by ion-induced nucleation, we were able to measure, for the first time, their progressive neutralization due to recombination with oppositely charged ions. A large fraction of the clusters carried a charge at 1.2 nm diameter. However, depending on particle growth rates and ion concentrations, charged clusters were largely neutralized by ion–ion recombination before they grew to 2.2 nm. At this size, more than 90 % of particles were neutral. In other words, particles may originate from ion-induced nucleation, although they are neutral upon detection at diameters larger than 2.2 nm. Observations at Hyytiälä, Finland, showed lower ion concentrations and a lower contribution of ion-induced nucleation than measured at CLOUD under similar conditions. Although this can be partly explained by the observation that ion-induced fractions decrease towards lower ion concentrations, further investigations are needed to resolve the origin of the discrepancy.
Nucleation and growth of aerosol particles from atmospheric vapors constitutes a major source of global cloud condensation nuclei (CCN). The fraction of newly formed particles that reaches CCN sizes is highly sensitive to particle growth rates, especially for particle sizes <10 nm, where coagulation losses to larger aerosol particles are greatest. Recent results show that some oxidation products from biogenic volatile organic compounds are major contributors to particle formation and initial growth. However, whether oxidized organics contribute to particle growth over the broad span of tropospheric temperatures remains an open question, and quantitative mass balance for organic growth has yet to be demonstrated at any temperature. Here, in experiments performed under atmospheric conditions in the Cosmics Leaving Outdoor Droplets (CLOUD) chamber at the European Organization for Nuclear Research (CERN), we show that rapid growth of organic particles occurs over the range from −25 ∘C to 25 ∘C. The lower extent of autoxidation at reduced temperatures is compensated by the decreased volatility of all oxidized molecules. This is confirmed by particle-phase composition measurements, showing enhanced uptake of relatively less oxygenated products at cold temperatures. We can reproduce the measured growth rates using an aerosol growth model based entirely on the experimentally measured gas-phase spectra of oxidized organic molecules obtained from two complementary mass spectrometers. We show that the growth rates are sensitive to particle curvature, explaining widespread atmospheric observations that particle growth rates increase in the single-digit-nanometer size range. Our results demonstrate that organic vapors can contribute to particle growth over a wide range of tropospheric temperatures from molecular cluster sizes onward.
The growth of aerosol due to the aqueous phase oxidation of sulfur dioxide by ozone was measured in laboratory-generated clouds created in the Cosmics Leaving OUtdoor Droplets (CLOUD) chamber at the European Organization for Nuclear Research (CERN). Experiments were performed at 10 and −10 °C, on acidic (sulfuric acid) and on partially to fully neutralised (ammonium sulfate) seed aerosol. Clouds were generated by performing an adiabatic expansion – pressurising the chamber to 220 hPa above atmospheric pressure, and then rapidly releasing the excess pressure, resulting in a cooling, condensation of water on the aerosol and a cloud lifetime of approximately 6 min. A model was developed to compare the observed aerosol growth with that predicted using oxidation rate constants previously measured in bulk solutions. The model captured the measured aerosol growth very well for experiments performed at 10 and −10 °C, indicating that, in contrast to some previous studies, the oxidation rates of SO2 in a dispersed aqueous system can be well represented by using accepted rate constants, based on bulk measurements. To the best of our knowledge, these are the first laboratory-based measurements of aqueous phase oxidation in a dispersed, super-cooled population of droplets. The measurements are therefore important in confirming that the extrapolation of currently accepted reaction rate constants to temperatures below 0 °C is correct.
The growth of aerosol due to the aqueous phase oxidation of sulfur dioxide by ozone was measured in laboratory-generated clouds created in the Cosmics Leaving OUtdoor Droplets (CLOUD) chamber at the European Organization for Nuclear Research (CERN). Experiments were performed at 10 and −10 °C, on acidic (sulfuric acid) and on partially to fully neutralised (ammonium sulfate) seed aerosol. Clouds were generated by performing an adiabatic expansion – pressurising the chamber to 220 hPa above atmospheric pressure, and then rapidly releasing the excess pressure, resulting in a cooling, condensation of water on the aerosol and a cloud lifetime of approximately 6 min. A model was developed to compare the observed aerosol growth with that predicted using oxidation rate constants previously measured in bulk solutions. The model captured the measured aerosol growth very well for experiments performed at 10 and −10 °C, indicating that, in contrast to some previous studies, the oxidation rates of SO2 in a dispersed aqueous system can be well represented by using accepted rate constants, based on bulk measurements. To the best of our knowledge, these are the first laboratory-based measurements of aqueous phase oxidation in a dispersed, super-cooled population of droplets. The measurements are therefore important in confirming that the extrapolation of currently accepted reaction rate constants to temperatures below 0 °C is correct.
There are strong indications that particles containing secondary organic aerosol (SOA) exhibit amorphous solid or semi-solid phase states in the atmosphere. This may facilitate deposition ice nucleation and thus influence cirrus cloud properties. However, experimental ice nucleation studies of biogenic SOA are scarce. Here, we investigated the ice nucleation ability of viscous SOA particles.
The SOA particles were produced from the ozone initiated oxidation of α-pinene in an aerosol chamber at temperatures in the range from −38 to −10 ◦C at 5–15 % relative humidity with respect to water to ensure their formation in a highly viscous phase state, i.e. semi-solid or glassy. The ice nucleation ability of SOA particles with different sizes was investigated with a new continuous flow diffusion chamber. For the first time, we observed heterogeneous ice nucleation of viscous α-pinene SOA in the deposition mode for ice saturation ratios between 1.3 and 1.4 significantly below the homogeneous freezing limit. The maximum frozen fractions found at temperatures between −36.5 and −38.3 °C ranged from 6 to 20 % and did not depend on the particle surface area. Global modelling of monoterpene SOA particles suggests that viscous biogenic SOA particles are indeed present in regions where cirrus cloud formation takes place. Hence, they could make up an important contribution to the global ice nuclei (IN) budget.
Atmospheric aerosols and their effect on clouds are thought to be important for anthropogenic radiative forcing of the climate, yet remain poorly understood1. Globally, around half of cloud condensation nuclei originate from nucleation of atmospheric vapours2. It is thought that sulfuric acid is essential to initiate most particle formation in the atmosphere3,4, and that ions have a relatively minor role5. Some laboratory studies, however, have reported organic particle formation without the intentional addition of sulfuric acid, although contamination could not be excluded6,7. Here we present evidence for the formation of aerosol particles from highly oxidized biogenic vapours in the absence of sulfuric acid in a large chamber under atmospheric conditions. The highly oxygenated molecules (HOMs) are produced by ozonolysis of α-pinene. We find that ions from Galactic cosmic rays increase the nucleation rate by one to two orders of magnitude compared with neutral nucleation. Our experimental findings are supported by quantum chemical calculations of the cluster binding energies of representative HOMs. Ion-induced nucleation of pure organic particles constitutes a potentially widespread source of aerosol particles in terrestrial environments with low sulfuric acid pollution.
About half of present-day cloud condensation nuclei originate from atmospheric nucleation, frequently appearing as a burst of new particles near midday1. Atmospheric observations show that the growth rate of new particles often accelerates when the diameter of the particles is between one and ten nanometres2,3. In this critical size range, new particles are most likely to be lost by coagulation with pre-existing particles4, thereby failing to form new cloud condensation nuclei that are typically 50 to 100 nanometres across. Sulfuric acid vapour is often involved in nucleation but is too scarce to explain most subsequent growth5,6, leaving organic vapours as the most plausible alternative, at least in the planetary boundary layer7,8,9,10. Although recent studies11,12,13 predict that low-volatility organic vapours contribute during initial growth, direct evidence has been lacking. The accelerating growth may result from increased photolytic production of condensable organic species in the afternoon2, and the presence of a possible Kelvin (curvature) effect, which inhibits organic vapour condensation on the smallest particles (the nano-Köhler theory)2,14, has so far remained ambiguous. Here we present experiments performed in a large chamber under atmospheric conditions that investigate the role of organic vapours in the initial growth of nucleated organic particles in the absence of inorganic acids and bases such as sulfuric acid or ammonia and amines, respectively. Using data from the same set of experiments, it has been shown15 that organic vapours alone can drive nucleation. We focus on the growth of nucleated particles and find that the organic vapours that drive initial growth have extremely low volatilities (saturation concentration less than 10−4.5 micrograms per cubic metre). As the particles increase in size and the Kelvin barrier falls, subsequent growth is primarily due to more abundant organic vapours of slightly higher volatility (saturation concentrations of 10−4.5 to 10−0.5 micrograms per cubic metre). We present a particle growth model that quantitatively reproduces our measurements. Furthermore, we implement a parameterization of the first steps of growth in a global aerosol model and find that concentrations of atmospheric cloud concentration nuclei can change substantially in response, that is, by up to 50 per cent in comparison with previously assumed growth rate parameterizations.
Under certain conditions, secondary organic aerosol (SOA) particles can exist in the atmosphere in an amorphous solid or semi-solid state. To determine their relevance to processes such as ice nucleation or chemistry occurring within particles requires knowledge of the temperature and relative humidity (RH) range for SOA to exist in these states. In the CLOUD experiment at CERN, we deployed a new in-situ optical method to detect the viscosity of α-pinene SOA particles and measured their transition from the amorphous viscous to liquid state. The method is based on the depolarising properties of laboratory-produced non-spherical SOA particles and their transformation to non-depolarising spherical liquid particles during deliquescence. We found that particles formed and grown in the chamber developed an asymmetric shape through coagulation. A transition to spherical shape was observed as the RH was increased to between 35 % at −10 ◦C and 80 % at −38 ◦C, confirming previous calculations of the viscosity transition conditions. Consequently, α-pinene SOA particles exist in a viscous state over a wide range of ambient conditions, including the cirrus region of the free troposphere. This has implications for the physical, chemical and ice-nucleation properties of SOA and SOA-coated particles in the atmosphere.
Under certain conditions, secondary organic aerosol (SOA) particles can exist in the atmosphere in an amorphous solid or semi-solid state. To determine their relevance to processes such as ice nucleation or chemistry occurring within particles requires knowledge of the temperature and relative humidity (RH) range for SOA to exist in these states. In the Cosmics Leaving Outdoor Droplets (CLOUD) experiment at The European Organisation for Nuclear Research (CERN), we deployed a new in situ optical method to detect the viscous state of α-pinene SOA particles and measured their transition from the amorphous highly viscous state to states of lower viscosity. The method is based on the depolarising properties of laboratory-produced non-spherical SOA particles and their transformation to non-depolarising spherical particles at relative humidities near the deliquescence point. We found that particles formed and grown in the chamber developed an asymmetric shape through coagulation. A transition to a spherical shape was observed as the RH was increased to between 35 % at −10 °C and 80 % at −38 °C, confirming previous calculations of the viscosity-transition conditions. Consequently, α-pinene SOA particles exist in a viscous state over a wide range of ambient conditions, including the cirrus region of the free troposphere. This has implications for the physical, chemical, and ice-nucleation properties of SOA and SOA-coated particles in the atmosphere.
There are strong indications that particles containing secondary organic aerosol (SOA) exhibit amorphous solid or semi-solid phase states in the atmosphere. This may facilitate heterogeneous ice nucleation and thus influence cloud properties. However, experimental ice nucleation studies of biogenic SOA are scarce. Here, we investigated the ice nucleation ability of viscous SOA particles.
The SOA particles were produced from the ozone initiated oxidation of α-pinene in an aerosol chamber at temperatures in the range from −38 to −10 °C at 5–15 % relative humidity with respect to water to ensure their formation in a highly viscous phase state, i.e. semi-solid or glassy. The ice nucleation ability of SOA particles with different sizes was investigated with a new continuous flow diffusion chamber. For the first time, we observed heterogeneous ice nucleation of viscous α-pinene SOA for ice saturation ratios between 1.3 and 1.4 significantly below the homogeneous freezing limit. The maximum frozen fractions found at temperatures between −39.0 and −37.2 °C ranged from 6 to 20 % and did not depend on the particle surface area. Global modelling of monoterpene SOA particles suggests that viscous biogenic SOA particles are indeed present in regions where cirrus cloud formation takes place. Hence, they could make up an important contribution to the global ice nucleating particle budget.
This preliminary checklist of Aphodiini south of the United States is prepared to provide published data for a future web-based checklist of all New World Aphodiinae. All species names are used in combination with their currently accepted generic name, creating many new combinations. A few genus-species combinations are discussed. New synonymies based on recent studies of type specimens are made: Aphodius azteca Harold = Aphodius multimaculosus Hinton; Aphodius ornatus Schmidt = Aphodius magnopunctatus Hinton; Aphodius caracaensis Petrovitz = Aphodius brasilicola Balthasar; Aphodius guatemalensis Bates = Aphodius striatipennis Petrovitz; Aphodius kuntzeni Schmidt = Aphodius amplinotum Gordon and Howden = Aphodius michiliensis Deloya; Aphodius bimaculosus Schmidt = Aphodius xalapensis Galante et al.; Aphodius caracanus Balthasar = Aphodius martinsi Petrovitz; Aphodius volxemi Harold = Aphodius squamifer Petrovitz.
Nine new species of Hyperaspis from various South American localities are described, illustrated, and compared with previously described taxa. New taxa are: Hyperaspis luciae, H. corcovado, H. divaricata, H. humboldti, H. mimica, H. praecipua, H. unimaculosa, H. drechseli, and H. esmeraldas. Hyperaspis pectoralis Crotch is recognized as a valid species of Hyperaspis and integrated into the existing classification.
The miscanthus mealybug, Miscanthicoccus miscanthi (Takahashi) (Hemiptera: Pseudococcidae), is newly reported as prey for the lady beetle Hyperaspis paludicola Schwarz (Coleoptera: Coccinellidae) at the Regan National Airport, Washington, DC (northern range extension). A new armored scale prey, Diaspidiotus ancyclus (Putnam) (Hemiptera: Diaspididae), for the lady beetle Microweisea misella (LeConte) (Coleoptera: Coccinellidae) is recorded. A range extension for Hyperaspis paludicola is reported.
We present the first measurement of fluctuations from event to event in the production of strange particles in collisions of heavy nuclei. The ratio of charged kaons to charged pions is determined for individual central Pb+Pb collisions. After accounting for the fluctuations due to detector resolution and finite number statistics we derive an upper limit on genuine non-statistical fluctuations, perhaps related to a first or second order QCD phase transition. Such fluctuations are shown to be very small.
Measurements of charged pion and kaon production in central Pb+Pb collisions at 40, 80 and 158 AGeV are presented. These are compared with data at lower and higher energies as well as with results from p+p interactions. The mean pion multiplicity per wounded nucleon increases approximately linearly with s_NN^1/4 with a change of slope starting in the region 15-40 AGeV. The change from pion suppression with respect to p+p interactions, as observed at low collision energies, to pion enhancement at high energies occurs at about 40 AGeV. A non-monotonic energy dependence of the ratio of K^+ to pi^+ yields is observed, with a maximum close to 40 AGeV and an indication of a nearly constant value at higher energies.The measured dependences may be related to an increase of the entropy production and a decrease of the strangeness to entropy ratio in central Pb+Pb collisions in the low SPS energy range, which is consistent with the hypothesis that a transient state of deconfined matter is created above these energies. Other interpretations of the data are also discussed.
Bose-Einstein correlations of charged kaons were measured near mid-rapidity in central Pb+Pb collisions at 158 A GeV by the NA49 experiment at the CERN SPS. Source radii were extracted using the Yano-Koonin-Podgoretsky and Bertsch-Pratt parameterizations. The results are compared to published pion data. The measured m_perp dependence for kaons and pions is consistent with collective transverse expansion of the source and a freeze-out time of about 9.5 fm.
The large acceptance and high momentum resolution as well as the significant particle identification capabilities of the NA49 experiment at the CERN SPS allow for a broad study of fluctuations and correlations in hadronic interactions. In the first part recent results on event-by-event charge and p_t fluctuations are presented. Charge fluctuations in central Pb+Pb reactions are investigated at three different beam energies (40, 80, and 158 AGeV), while for the p_t fluctuations the focus is put on the system size dependence at 158 AGeV. In the second part recent results on Bose Einstein correlations of h-h- pairs in minimum bias Pb+Pb reactions at 40 and 158 AGeV, as well as of K+K+ and K-K- pairs in central Pb+Pb collisions at 158 AGeV are shown. Additionally, other types of two particle correlations, namely pi p, Lambda p, and Lambda Lambda correlations, have been measured by the NA49 experiment. Finally, results on the energy and system size dependence of deuteron coalescence are discussed.
Rapidity distributions for Lambda and anti-Lambda hyperons in central Pb-Pb collisions at 40, 80 and 158 AGeV and for K 0 s mesons at 158 AGeV are presented. The lambda multiplicities are studied as a function of collision energy together with AGS and RHIC measurements and compared to model predictions. A different energy dependence of the Lambda/pi and anti-Lambda/pi is observed. The anti-Lambda/Lambda ratio shows a steep increase with collision energy. Evidence for a anti-Lambda/anti-p ratio greater than 1 is found at 40 AGeV.
The energy dependence of hadron production in central Pb+Pb collisions is presented and discussed. In particular, midrapidity m_T-spectra for pi-, K-, K+, p, bar p, d, phi, Lambda and bar Lambda at 40, 80 and 158 AGeV are shown. In addition Xi and Omega spectra are available at 158 AGeV. The spectra allow to determine the thermal freeze-out temperature T and the transverse flow velocity beta_T at the three energies. We do not observe a significant energy dependence of these parameters; furthermore there is no indication of early thermal freeze-out of Xi and Omega at 158 AGeV. Rapidity spectra for pi-, K-, K+ and phi at 40, 80 and 158 AGeV are shown, as well as first results on Omega rapidity distributions at 158 AGeV. The chemical freeze-out parameters T and mu_B at the three energies are determined from the total yields. The parameters are close to the expected phase boundary in the SPS energy range and above. Using the total yields of kaons and lambdas, the energy dependence of the strangeness to pion ratio is discussed. A maximum in this ratio is found at 40 AGeV. This maximum could indicate the formation of deconfined matter at energies above 40 AGeV. A search for open charm in a large sample of 158 AGeV events is presented. No signal is observed. This result is compared to several model predictions.
Aphodius alabama, new species, collected in burrows of the southeastern pocket gopher Geomys pinetus Rafinesque, is described. Aphodius dyspistus Skelley & Woodruff, A. hubbelli S. & W., A. platypleurus S. & W., and A. tanytarsus S. & W., collected with A. alubarna, are all recorded from southeastern Alabama.
Experiment NA49 at the Cern SPS uses a large acceptance detector for a systematic study of particle yields and correlations in nucleus-nucleus, nucleon-nucleus and nucleon-nucleon collisions. Preliminary results for Pb+Pb collisions at 40, 80 and 158 A*GeV beam energy are shown and compared to measurements at lower and higher energies.
Rapidity distributions for $\Lambda$ and $\bar{\Lambda}$ hyperons in central Pb-Pb collisions at 40, 80 and 158 A$\cdot$GeV and for ${\rm K}_{s}^{0}$ mesons at 158 A$\cdot$GeV are presented. The lambda multiplicities are studied as a function of collision energy together with AGS and RHIC measurements and compared to model predictions. A different energy dependence of the $\Lambda/\pi$ and $\bar{\Lambda}/\pi$ is observed. The $\bar{\Lambda}/\Lambda$ ratio shows a steep increase with collision energy. Evidence for a $\bar{\Lambda}/\bar{\rm p}$ ratio greater than 1 is found at 40 A$\cdot$GeV.
Systematic revision of the genus Orodaliscoides Schmidt, 1913 (Coleoptera: Scarabaeidae: Aphodiinae)
(2012)
The species belonging to the genus Orodaliscoides Schmidt (Coleoptera: Scarabaeidae: Aphodiinae) are redescribed and figured. The following new combinations are proposed: Orodaliscoides fimbripes (Brown, 1928) and Orodaliscoides giulianii (Gordon, 1977).
Even in V1, where neurons have well characterized classical receptive fields (CRFs), it has been difficult to deduce which features of natural scenes stimuli they actually respond to. Forward models based upon CRF stimuli have had limited success in predicting the response of V1 neurons to natural scenes. As natural scenes exhibit complex spatial and temporal correlations, this could be due to surround effects that modulate the sensitivity of the CRF. Here, instead of attempting a forward model, we quantify the importance of the natural scenes surround for awake macaque monkeys by modeling it non-parametrically. We also quantify the influence of two forms of trial to trial variability. The first is related to the neuron’s own spike history. The second is related to ongoing mean field population activity reflected by the local field potential (LFP). We find that the surround produces strong temporal modulations in the firing rate that can be both suppressive and facilitative. Further, the LFP is found to induce a precise timing in spikes, which tend to be temporally localized on sharp LFP transients in the gamma frequency range. Using the pseudo R2 as a measure of model fit, we find that during natural scene viewing the CRF dominates, accounting for 60% of the fit, but that taken collectively the surround, spike history and LFP are almost as important, accounting for 40%. However, overall only a small proportion of V1 spiking statistics could be explained (R2~5%), even when the full stimulus, spike history and LFP were taken into account. This suggests that under natural scene conditions, the dominant influence on V1 neurons is not the stimulus, nor the mean field dynamics of the LFP, but the complex, incoherent dynamics of the network in which neurons are embedded.
Dilatitibialis Duverger (61 species) (Coleoptera: Coccinelidae: Coccidulinae; Hyperaspidini) is discussed, species described, illustrations provided, and a key to all recognized taxa included. Cleothera cognata Mulsant, Cleothera cruciferae Mulsant, Cleothera fuscomaculata Mulsant, Cleothera gaynoni Mulsant, Cleothera glyphica Mulsant, Cleothera jucunda Mulsant, Cleothera luteola Mulsant, Cleothera mulsanti Kirsch, Cleothera oseryi Mulsant, Cleothera poortmanni Mulsant, Cleothera scenica Mulsant, Cleothera semicincta Weise, Cleothera tropicalis Mulsant, Hinda guttipennis Weise, Hyperaspis carolinae Crotch, Hyperaspis ceciliae Crotch, Hyperaspis dilatata Crotch, Hyperaspis florifera Vogel, Hyperaspis gravabilis Brèthes, Hyperaspis hybridula Crotch, Hyperaspis laterinotata Brèthes, Hyperaspis silvani Crotch, and Hyperaspis suzannae Crotch are transferred to Dilatitibialis, becoming new combinations. Lectotypes are designated for D. boliviana, D. cognata, D. florifera, D. fuscomaculata, D. gaynoni, D. glyphica, D. gravabilis, D. guttipennis, D. luteola, D. jucunda, D. mulsanti. D. poortmanni, D. retigera, D. scenica, D. semicincta, and D. staudingeri. A total of 38 new species of Dilatitibialis are described: Dilatitibialis annie, D. carmen, D. cindy, D. connie, D. crystal, D. dawn, D. diana, D. edith, D. edna, D. elaine, D. ellen, D. emily, D. ethel, D. fallax, D. florence, D. gladys, D. grace, D. josephine, D. kim, D. lillian, D. lois, D. marjorie, D. norma, D. paula, D. peggy, D. phyllis, D. rita, D. robin, D. rosa, D. shannon, D. sheila, D. sherry, D. sylvia, D. thelma, D. tiffany, D. tina, D. tracy, and D. wendy. Corrections are made to titles of previous Parts of this series, as follows: South American Coccinellidae, Part XII (Gordon 2007) is changed to Part XIII; South American Coccinellidae, Part XII (Gordon et al. 2013) is changed to Part XIV.
Cyrea Gordon and Canepari (121 species) and Tiphysa Mulsant (2 species) are discussed, species are described, illustrations are provided, and a key to all recognized species is included. New synonyms recognized are:
Hyperaspis arrowi var. darwini Brèthes = Cyrea arrowi (Brèthes); Hyperaspis trivittata Weise, Hyperaspis mundula Weise = Cyrea emiliae (Mulsant); Cleothera scapulata Mulsant, Cleothera mercabilis Mulsant, Hyperaspis iheringi Weise = Cyrea flavoguttata (Mulsant); Cleothera gracilis Mulsant = Cyrea hexastigma (Mulsant); Cleothera triacantha Mulsant = Cyrea novemsignata (Herbst); Cleothera distinguenda Mulsant = Cyrea ormanceayi (Mulsant); Cleothera sexnotata Brèthes = Cyrea quinquenotata (Mulsant); Cleothera schaufussi Vogel and Hyperaspis adelaida Gorham = Cyrea tessulata (Mulsant). A total of 76 new species of Cyrea are described: Cyrea agnes, C. allison, C.alma, C. annette, C. arlene, C. audrey, C. beatrice, C. bernice, C. bessie, C. brittany, C. carla, C. charlene, C. claudia, C. colleen, C. constance, C. courtney, C. dana, C. dolores, C. dora, C. eileen, C. ella, elsie, erica, georgia, gertrude, gina, glenda, heidi, holly, ida, jackie, jeanne, jeannette, jessie, jo, C. joy, C. june, C. katie, C. kristen, C. laurie, C. lillie, C. lucille, C. lucy, C. lydia, C. marcia, C. marian, C. marion, C. marlene, C. mattie, C. maureen, C. maxine, C. melanie, C. melinda, C. minnie, C. natalia, C. nellie, C. pearl, C. pseudospinalis, C. renee, C. roberta, C. rosemary, C. samantha, C. stacy, C. stella, C. sue, C. tamara, C. tanya, C. tara, C. terry, C. vanessa, C. vera, C. vicki, C. viola, C. vivian, C. willie, C. wilma, C. yolanda, C.
yvonne. Lectotypes here designated for C. collaris, C. compta, C. distinguenda, C. exclamationis, C. fasciata, C. ferruginiceps, C. flavoguttata, C. iheringi, C. languida, C. maculosa, C. melaneura, C. mundula, C. noticollis, C. novemsignata, C. ormanceayi, C. ornaticolis, C. quinquenotata, C. renifera, C. schaufussi, C. sexguttata, C. spinalis, C. tessulata, C. trepida, C. triacantha
Genera of Brachiacanthini (Coleoptera: Coccinellidae: Hyperaspidinae) are discussed and a key to all recognized genera provided. Cyrea, new genus, is proposed, and Serratitibia, new genus, is erected and revised, Cleothera Mulsant and Hinda Mulsant are recognized as valid genera and revised. Helesius caseyi Sicard is transferred to Hinda and recognized as a synonym of Hinda designata Mulsant, new synonymy. Brachiacantha brethesi (Korschefsky), Cleothera abendrothi Kirsch, Cleothera ambigua Mulsant, Cleothera bisquatuorpustulata Mulsant, Cleothera decemsignata Mulsant, Cleothera gaillardi Mulsant, Cleothera humerata Mulsant, Cleothera tortuosa Mulsant, Cleothera traili Brèthes, Cleothera uncinata Mulsant, Hinda joeli Almeida and Milléo, Hinda modesta Weise, Hinda regularis Kirsch, Hyperaspis aliciae Crotch, and Hyperaspis fraudulenta Kirsch are transferred to Serratitibia, becoming new combinations. One new species of Hinda, H. ecuadorica, is described. A total of 73 new species of Serratitibia are described: Serratitibia amanda, S. andrea, S. angela, S. anna, S. ashley, S. barbara, S. barclayi, S. betty, S. beverly, S. bonnie, S. brenda, S. cheryl, S. christine, S. cynthia, S. debra, S. denise, S. donna, S. doris, S. elizabeth, S. evelyn, S. frances, S. gloria, S. heather, S. helen, S. irene, S. jacqueline, S. janet, S. janice, S. jean, S. jennifer, S. joan, S. joyce, S. judith, S. judy, S. julie, S. karen, S. katherine, S. kathleen, S. kathy, S. kelly, S. kimberly, S. laura, S. linda, S. lisa, S. loreto, S. lori, S. louise, S. margaret, S. marilyn, S. mary, S. martha, S. melissa, S. michelle, S. mildred, S. nancy, S. nicole, S. pamela, S. paprzycki, S. patricia, S. quincemil, S. rachel, S. rebecca, S. rose, S. ruby, S. ruth, S. sarah, S. satipoensis, S. shirley, S. stephanie, S. susan, S. tammy, S. teresa, and S. virginia. Lectotypes are here designated for Serratitibia lividipes, S. gaillardi, S. decemsignata, S. abendrothi, and S. ambigua.
The new species Cephalocyclus majomaensis and Oscarinus cabreroi from Mexico are described and figured. While studying specimens from Mexico to complete a systematic revision of the Aphodiinae (Coleoptera: Scarabaeidae) of that region, we found a couple of species new to science. They belong to the genera Cephalocyclus Dellacasa, Gordon and Dellacasa, 1998 and Oscarinus Gordon and Skelley, 2007, and are described here.
This paper reports on the scarab beetles collected during a survey of nonparasitic arthopods living in burrows of the southeastern pocket gopher (Geomys pinetus Rafinesque, Geomyidae). Three new species are described: Aphodius bakeri, A. baileyi and A. gambrinus. A key to species of Aphodius occurring in these burrows is presented. Distributional data is provided for species of Aphodius and one species of Euphoria
occurring in this microhabitat. Aspects of life histories of burrow inhabiting insects are speculated upon.
Genera of Cephaloscymnini (Coleoptera: Coccinellidae: Coccidulinae) are discussed and a key to all recognized genera and species is provided. Succinctonotum, new genus, is proposed. Scymnus laboulbenii Mulsant and Prodilis maculata Weise are transferred to Neaporia as new combinations. Prodiloides bipunctata Weise, and Neaporia compta are transferred to Prodilis as new combinations. Neaporia cuprea Gorham is considered a junior synonym of Neaporia viridiscens Gorham and Cephaloscymnus bruchi Weise a junior synonym of Prodilis volgus Mulsant. New species described in Cephaloscymnus are C. beulah, C. candice, C. juanita. New species described in Neaporia are N. becky, N. bobbie, N. brandy, N. carole, N. cassandra, N. christy, N. daisy, N. deanna, N. dianne, N. felicia, N. gwendolyn, N. hilda, N. irma, N. jennie, N. jenny, N. kay, N. kayla, N. kristine, N. leah, N. lena, N. leona, N. longifrons, N. mabel, N. mae, N. margie, N. marsha, N. miriam, N. misty, N. myrtle, N. naomi, N. nina, N. nora, N. olga, N. opal, N. patsy, N. penny, N. priscilla, N. shelley, N. sonia, N. tracey, and N. violet. New species described in Succinctonotum is S. frosti. New species described in Prodilis are P. ada, P. alberta, P. alison, P. amelia, P. angie, P. araguaensis, P. bartletti, P. belinda, P. blanche, P. brandi, P. cecilia, P. claire, P. cora, P. dubitalis, P. erika, P. eunice, P. fannie, P. faye, P. flora, P. geneva, P. guadalupe, P. harriet, P. hattie, P. inez, P. iris, P. isabel, P. jan, P. janie, P. joanna, P. jodi, P. katrina, P. kristi, P. kristy, P. lindsey, P. lola, P. lula, P. lynda, P. madeline, P. maggie, P. mamie, P. margarita, P. maryann, P. melody, P. molly, P. monique, P. natasha, P. olivia, P. pecki, P. ramona, P. rosie, P. sabrina, P. sandy, P. shelley, P. sherri, P. sheryl, P. sonya, P. susie, and P. yvette. Ponaria, new genus of Coccidulini is proposed. Neaporia caerulea Gorham is transferred to Ponaria as a new combination. New species described in Ponaria are P. daviesi, P. hurtadoi, and P. paprzyckii. Lectotypes are here designated for Neaporia arrowi, N. coelestis, N. metallica, N. guatemalana, N. indagator, and Prodilis pallidifrons.
The American species belonging to the genus Gonaphodiellus Schmidt (Coleoptera: Scarabaeidae: Aphodiinae) are redescribed and figured. Two new genera are described: Gonaphodioides and Gonaphodiopsis. Fourteen new species are described: Gonaphodiellus arcanus, G. cerropuntanus, G. manantlanicus, G. martinpierai, G. omiltemicus, G. sacatepequezis, Gonaphodioides newtoni, G. ratcliffei, G. skelleyi, Gonaphodiopsis deloyai, G. hypogea, G. montesdeocai, G. pachecoi, G. teopiscaensis. The lectotype of Aphodius columbicus (Harold, 1880) is designated. The following new combinations are proposed: Gonaphodiellus nigrinus (Schmidt, 1916), Gonaphodioides acutecernans (Balthasar, 1960), Gonaphodioides chapini (Hinton, 1934), Gonaphodioides columbicus (Harold, 1880), Gonaphodioides sincerus (Petrovitz, 1973). Aphodius (Gonaphodiellus) xalapensis Galante, Stebnicka and Verdú, 2003 is placed as a junior synonym of Gonaphodiellus bimaculosus (Schmidt, 1909), new synonymy. Aphodius ataenioides Hinton, 1938 and Aphodius (Blackburneus) castanescens Petrovitz, 1973 are placed as junior synonyms of Gonaphodioides chapini (Hinton, 1934), new synonymies.
Brachiacantha Dejean (Coccinellinae: Hyperaspidini), containing 49 species, is discussed, species described, illustrations provided, and a key to all recognized taxa included. Coccinella octopustulata F., Cleothera groendali Mulsant, Hyperaspis argentinica Weise, Hyperaspis blandula Weise, and Hyperaspis egae Crotch are transferred to Brachiacantha. Cleothera billoti parva Mulsant is recognized as a valid species and transferred to Brachiacantha. Brachiacantha arrowi Brèthes, Brachiacantha australe Leng, Brachiacantha manni Nunenmacher, and Brachiacantha propria Kirsch are recognized as synonyms of Brachiacantha groendali (Mulsant). A total of 29 new species of Brachiacantha are described; B. amber, B. anita, B. april, B. cathy, B. clara, B. charlotte, B. danielle, B. darlene, B. debbie, B. eleanor, B. emma, B. esther, B. eva, B. gail, B. hazel, B. jamie, B. joanne, B. jill, B. juanita, B. lauren, B. leslie, B. lynn, B. monica, B. pauline, B. pseudoarrowi, B. regina, B. sally, B. valerie, and B. veronica. Lectotypes are designated for B. argentinica (Weise), B. armandi (Mulsant), B. arrowi Brèthes, B. bahiensis Brethès, B. bilineata Weise, B. blandula Weise, B. bruchi Weise, B. loricata (Mulsant), B. octopustulata (F.), B. propria Kirsch.