394 research outputs found
Theory of ac electrokinetic behavior of spheroidal cell suspensions with an intrinsic dispersion
The dielectric dispersion, dielectrophoretic (DEP) and electrorotational (ER)
spectra of spheroidal biological cell suspensions with an intrinsic dispersion
in the constituent dielectric constants are investigated. By means of the
spectral representation method, we express analytically the characteristic
frequencies and dispersion strengths both for the effective dielectric constant
and the Clausius-Mossotti factor (CMF). We identify four and six characteristic
frequencies for the effective dielectric spectra and CMF respectively, all of
them being dependent on the depolarization factor (or the cell shape). The
analytical results allow us to examine the effects of the cell shape, the
dispersion strength and the intrinsic frequency on the dielectric dispersion,
DEP and ER spectra. Furthermore, we include the local-field effects due to the
mutual interactions between cells in a dense suspension, and study the
dependence of co-field or anti-field dispersion peaks on the volume fractions.Comment: accepted by Phys. Rev.
Photosynthetic characteristics of summer maize under different planting patterns and the responses to nitrogen application of previous crop
Maize (Zea mays L.) is one of the most important grain crops in the North China Plain. Management practices affect the photosynthetic characteristics and the production of summer maize. This two-year (2014-2015) study examined the effects of different planting patterns and the application of nitrogen to previous winter wheat (Triticum aestivum L.) on the photosynthetic characteristics, yield and radiation use efficiency (RUE) of summer maize. Field experiments used a two-factor split-plot design with three replicates at Taian, Shandong Province, China (36°09′ N, 117°09′ E). The experiments involved two planting patterns (ridge planting, RP; and uniform row planting, UR) and two nitrogen application levels of previous winter wheat (N1, 112.50 kg ha-1; N2, 225.00 kg ha-1). The results indicated that the application of nitrogen on previous crop and ridge planting of the following crop had significant effects on the photosynthetic characteristics and yields of summer maize. Compared with UR, this study found that RP increased the chlorophyll content index (CCI), leaf area index (LAI), net photosynthetic rate (Pn), dry matter (DM), yield and grain RUE by 4.1%, 6.3%, 5.2%, 6.4%, 8.9% and 9.4%, respectively. The CCI, LAI, Pn, yield, and grain RUE of N2 were 9.7%, 3.3%, 3.7%, 10.0% and 10.1% higher than those of N1, respectively. RP combined with the application of nitrogen on previous crop of winter wheat could increase the CCI, LAI, Pn, DM, ultimately increasing the grain yield and RUE of the following summer’s maize. It was concluded that previous crop nitrogen application and RP pattern treatment resulted in optimal cropping conditions for the North China plain
Search for Invisible Decays of and in and
Using a data sample of decays collected with the BES
II detector at the BEPC, searches for invisible decays of and
in to and are performed.
The signals, which are reconstructed in final states, are used
to tag the and decays. No signals are found for the
invisible decays of either or , and upper limits at the 90%
confidence level are determined to be for the ratio
and for . These are the first
searches for and decays into invisible final states.Comment: 5 pages, 4 figures; Added references, Corrected typo
Study of J/psi decays to Lambda Lambdabar and Sigma0 Sigma0bar
The branching ratios and Angular distributions for J/psi decays to Lambda
Lambdabar and Sigma0 Sigma0bar are measured using BESII 58 million J/psi.Comment: 11 pages, 5 figure
Measurements of the observed cross sections for exclusive light hadrons containing at , 3.650 and 3.6648 GeV
By analyzing the data sets of 17.3, 6.5 and 1.0 pb taken,
respectively, at , 3.650 and 3.6648 GeV with the BES-II
detector at the BEPC collider, we measure the observed cross sections for
, , ,
and at the three energy
points. Based on these cross sections we set the upper limits on the observed
cross sections and the branching fractions for decay into these
final states at 90% C.L..Comment: 7 pages, 2 figure
Search for the Rare Decays J/Psi --> Ds- e+ nu_e, J/Psi --> D- e+ nu_e, and J/Psi --> D0bar e+ e-
We report on a search for the decays J/Psi --> Ds- e+ nu_e + c.c., J/Psi -->
D- e+ nu_e + c.c., and J/Psi --> D0bar e+ e- + c.c. in a sample of 5.8 * 10^7
J/Psi events collected with the BESII detector at the BEPC. No excess of signal
above background is observed, and 90% confidence level upper limits on the
branching fractions are set: B(J/Psi --> Ds- e+ nu_e + c.c.)<4.8*10^-5, B(J/Psi
--> D- e+ nu_e + c.c.) D0bar e+ e- + c.c.)<1.1*10^-5Comment: 10 pages, 4 figure
Measurements of J/psi Decays into 2(pi+pi-)eta and 3(pi+pi-)eta
Based on a sample of 5.8X 10^7 J/psi events taken with the BESII detector,
the branching fractions of J/psi--> 2(pi+pi-)eta and J/psi-->3(pi+pi-)eta are
measured for the first time to be (2.26+-0.08+-0.27)X10^{-3} and
(7.24+-0.96+-1.11)X10^{-4}, respectively.Comment: 11 pages, 6 figure
BESII Detector Simulation
A Monte Carlo program based on Geant3 has been developed for BESII detector
simulation. The organization of the program is outlined, and the digitization
procedure for simulating the response of various sub-detectors is described.
Comparisons with data show that the performance of the program is generally
satisfactory.Comment: 17 pages, 14 figures, uses elsart.cls, to be submitted to NIM
Study of
New data are presented on from a sample of 58M
events in the upgraded BES II detector at the BEPC. There is a
conspicuous signal for and a peak at higher mass which
may be fitted with . From a combined analysis with
data, the branching ratio
is at the 95%
confidence level.Comment: 11 pages, 5 figures. Submitted to Phys. Lett.
Partial wave analysis of J/\psi \to \gamma \phi \phi
Using events collected in the BESII detector, the
radiative decay is
studied. The invariant mass distribution exhibits a near-threshold
enhancement that peaks around 2.24 GeV/.
A partial wave analysis shows that the structure is dominated by a
state () with a mass of
GeV/ and a width of GeV/. The
product branching fraction is: .Comment: 11 pages, 4 figures. corrected proof for journa
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