145 research outputs found
Selection of Trichogramma for inundative biological control
This thesis presents a study of the potential for biological control of lepidopterous pests on cabbage crops in the Netherlands, by means of inundative releases of the egg parasite Trichogramma (Hymenoptera, Trichogrammatidae). The objective of this study is to investigate the usefulness of a predictive approach to the development of a biological control program. Chapter 1 provides an introduction to the three basic elements of this study: the principles of biological control, the use of Trichogramma as a control agent and the host species occurring on cabbage crops.The main theme of this study is the selection, by means of laboratory investigations and experimental field releases, of candidate strains of the parasite for practical application. This topic is discussed in chapter 2. Selection experiments were conducted using a collection of sixty geographical strains maintained in the laboratory. The methodology of culturing both parasites and hosts, and of observing female-parasite behaviour are described in chapter 3. Results of experiments on possible selection criteria involving various strains are presented in the subsequent chapters (4-9).Adaptability of parasitization activity to field-temperature conditions was investigated for all strains (chapter 4). Strains with a high performance at low temperature were used for studies on differences in host-selection behaviour between strains, i.e. host- age selection (chapter 5) and host-species selection (chapter 6). Studies on host recognition (chapter 7) and host suitability (chapter 8) were conducted to determine how and why female wasps distinguish between host species.Candidate strains selected on the basis of the laboratory research were released in Brussels sprouts fields with natural pest populations. During four seasons (1982-85) the performance of two strains in parasitism of the major host species was compared, in order to test the validity of the pre-introductory selection criteria (chapter 9). Finally, a comprehensive discussion of the results of this study is provided in chapter 10.</TT
Identified particles in Au+Au collisions at sqrt{s_NN} = 200 GeV
The yields of identified particles have been measured at RHIC for Au+Au
collisions at sqrt{s_NN} = 200 GeV using the PHOBOS spectrometer. The ratios of
antiparticle to particle yields near mid-rapidity are presented. The first
measurements of the invariant yields of charged pions, kaons and protons at
very low transverse momenta are also shown.Comment: 4 pages, 4 figures, Contribution to Quark Matter 2002, Nantes,
France, July 200
Universal Behavior of Charged Particle Production in Heavy Ion Collisions
The PHOBOS experiment at RHIC has measured the multiplicity of primary
charged particles as a function of centrality and pseudorapidity in Au+Au
collisions at sqrt(s_NN) = 19.6, 130 and 200 GeV. Two kinds of universal
behavior are observed in charged particle production in heavy ion collisions.
The first is that forward particle production, over a range of energies,
follows a universal limiting curve with a non-trivial centrality dependence.
The second arises from comparisons with pp/pbar-p and e+e- data.
N_tot/(N_part/2) in nuclear collisions at high energy scales with sqrt(s) in a
similar way as N_tot in e+e- collisions and has a very weak centrality
dependence. This feature may be related to a reduction in the leading particle
effect due to the multiple collisions suffered per participant in heavy ion
collisions.Comment: 4 Pages, 5 Figures, contributed to the Proceedings of Quark Matter
2002, Nantes, France, 18-24 July 200
Recent Results from PHOBOS at RHIC
The PHOBOS experiment at RHIC has recorded measurements for Au-Au collisions
spanning nucleon-nucleon center-of-mass energies from 19.6 GeV to 200 GeV.
Global observables such as elliptic flow and charged particle multiplicity
provide important constraints on model predictions that characterize the state
of matter produced in these collisions. The nearly 4 pi acceptance of the
PHOBOS experiment provides excellent coverage for complete flow and
multiplicity measurements. Results including beam energy and centrality
dependencies are presented and compared to elementary systems.Comment: 4 pages, 4 figures, proceedings from PANIC02 in Osaka, Japa
Global Observations from PHOBOS
Particle production in Au+Au collisions has been measured in the PHOBOS
experiment at RHIC for a range of collision energies. Three empirical
observations have emerged from this dataset which require theoretical
examination. First, there is clear evidence of limiting fragmentation. Namely,
particle production in central Au+Au collisions, when expressed as
(), becomes energy independent at high energy for a
broad region of around . This energy-independent region grows
with energy, allowing only a limited region (if any) of longitudinal
boost-invariance. Second, there is a striking similarity between particle
production in e+e- and Au+Au collisions (scaled by the number of participating
nucleon pairs). Both the total number of produced particles and the
longitudinal distribution of produced particles are approximately the same in
e+e- and in scaled Au+Au. This observation was not predicted and has not been
explained. Finally, particle production has been found to scale approximately
with the number of participating nucleon pairs for . This scaling
occurs both for the total multiplicity and for high \pT particles (3 <\pT<
4.5 GeV/c).Comment: QM2002 plenary talk, 10 pages, 11 figure
Tabela de vida de fertilidade de cinco linhagens de Trichogramma pretiosum Riley (Hym.: Trichogrammatidae) criadas em ovos de Tuta absoluta (Merick) (Lep.: Gelechiidae), sob temperaturas constantes e alternadas
Charged hadron transverse momentum distributions in Au+Au collisions at sqrt(s_NN) = 200 GeV
We present transverse momentum distributions of charged hadrons produced in
Au+Au collisions at sqrt(s_NN) = 200 GeV. The spectra were measured for
transverse momenta p_T from 0.25 to 4.5 GeV/c in a rapidity range of 0.2 < y_pi
< 1.4. The evolution of the spectra is studied as a function of collision
centrality, from 65 to 344 participating nucleons. The results are compared to
data from proton-antiproton collisions and Au+Au collisions at lower RHIC
energies. We find a significant change of the spectral shape between
proton-antiproton and peripheral Au+Au collisions. Comparing peripheral to
central Au+Au collisions, we find that the yields at high p_T exhibit
approximate scaling with the number of participating nucleons, rather than
scaling with the number of binary collisions.Comment: 5 pages, 4 figures, submitted to Phys.Lett.
Parasitismo de Trichogramma pretiosum Riley, 1879 (Hymenoptera: Trichogrammatidae) em diferentes hospedeiros e cores de cartelas
Measurement of the azimuthal anisotropy of Y(1S) and Y(2S) mesons in PbPb collisions at âNN = 5.02 TeV
The second-order Fourier coefficients (Ï
) characterizing the azimuthal distributions of ΄(1S) and ΄(2S) mesons produced in PbPb collisions at = 5.02 TeV are studied. The ΄mesons are reconstructed in their dimuon decay channel, as measured by the CMS detector. The collected data set corresponds to an integrated luminosity of 1.7 nb. The scalar product method is used to extract the Ï
coefficients of the azimuthal distributions. Results are reported for the rapidity range |y| < 2.4, in the transverse momentum interval 0 < p < 50 GeV/c, and in three centrality ranges of 10â30%, 30â50% and 50â90%. In contrast to the J/Ï mesons, the measured Ï
values for the ΄ mesons are found to be consistent with zero
- âŠ