10,367 research outputs found
Which Strategy Maximizes the Innovation Output of Firms in China: Using a Control or an Entrepreneurial Sphere?
Innovation is a key stimulus for firms’ survival and growth. However, many of Chinese firms fail to make it due to the lack of adequate financial resources. Previous studies have been deeply investigated the relationships between financial resources and firms’ innovation performance. This paper extends such stream of the literature by focusing on a vital question for entrepreneurs: how to maximize innovation output under resource constraints. Based on an extensive dataset collected at Zhongguancun Science Park (ZSP), Beijing, China, over the period 2011-2014, this paper discusses whether entrepreneurs should pursue extra public funding (control sphere). Besides, this paper also provides empirical evidence for entrepreneurs to make proper choices about resource allocation (entrepreneurial sphere). This paper hypothesizes that enterprises allocating resources by using the entrepreneurial sphere, rather than the control sphere, can advance innovation output. To test our hypothesis, this paper adopts a dynamic panel model estimated by a bootstrap-based bias correction procedure. We find that, in advancing innovative performance, the entrepreneurial sphere is more effective than control. Indeed, at the overall level, the crowding out effect merely offsets the additionality effect when enterprises pursue extra public funding. Therefore, the control sphere does not play an essential role in advancing innovation performance. Thus, extra efforts in that direction will turn out to be in vain. Consequently, as a policy implication we claim that entrepreneurs should spend more time and energy on productive activities rather than lobbying and rent-seeking. In addition, managers should allocate resources properly for internal knowledge creation, external knowledge absorption and S&T activities
NMR Search for the Spin Nematic State in LaFeAsO Single Crystal
We report a 75-As single crystal NMR investigation of LaFeAsO, the parent
phase of a pnictide high Tc superconductor. We demonstrate that spin dynamics
develop a strong two-fold anisotropy within each orthorhombic domain below the
tetragonal-orthorhombic structural phase transition at T[TO]~156 K. This
intermediate state with a dynamical breaking of the rotational symmetry freezes
progressively into a spin density wave (SDW) below T[SDW]~142 K. Our findings
are consistent with the presence of a spin nematic state below T[TO] with an
incipient magnetic order.Comment: Revised manuscript accepted for publication in Phys. Rev. Let
^{59}Co NMR evidence for charge ordering below T_{CO}\sim 51 K in Na_{0.5}CoO_2
The CoO layers in sodium-cobaltates NaCoO may be viewed as
a spin triangular-lattice doped with charge carriers. The underlying
physics of the cobaltates is very similar to that of the high cuprates.
We will present unequivocal Co NMR evidence that below ,
the insulating ground state of the itinerant antiferromagnet
NaCoO () is induced by charge ordering.Comment: Phys. Rev. Lett. 100 (2008), in press. 4 figure
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High Sensitivity Hot-wire based Wind Velocity Sensor using Co-doped Fiber and Fiber Bragg Grating for use in mining applications
In this paper, a mathematical model of the temperature distribution in a fiber-optic version of the familiar 'hot-wire' wind velocity sensor has been established and a practical sensor device realized and investigated for use in coal mining applications. The relationship between the dynamic measurement range, the sensitivity, the sensor probe surface heat transfer coefficient and the wind speed (in the region where the sensor probe is located) has been investigated. The veracity of the predicted performance of the fiber-optic hot-wire mathematical model has then been verified by experiment. The sensitivity of the sensor probe to wind velocity was measured across several wind velocity ranges to be ∼1500pm per unit m/s wind velocity (in the range of 0 - 0.5 m/s), ∼330pm per unit m/s in the range 0.5 - 2 m/s and ∼50pm per unit m/s in the range of 2.0 - 4.5 m/s
Multiwavelength observations of a partially eruptive filament on 2011 September 8
In this paper, we report our multiwavelength observations of a partial
filament eruption event in NOAA active region 11283 on 2011 September 8. A
magnetic null point and the corresponding spine and separatrix surface are
found in the active region. Beneath the null point, a sheared arcade supports
the filament along the highly complex and fragmented polarity inversion line.
After being activated, the sigmoidal filament erupted and split into two parts.
The major part rose at the speeds of 90150 km s before reaching the
maximum apparent height of 115 Mm. Afterwards, it returned to the solar
surface in a bumpy way at the speeds of 2080 km s. The rising and
falling motions were clearly observed in the extreme-ultravoilet (EUV), UV, and
H wavelengths. The failed eruption of the main part was associated with
an M6.7 flare with a single hard X-ray source. The runaway part of the
filament, however, separated from and rotated around the major part for 1
turn at the eastern leg before escaping from the corona, probably along
large-scale open magnetic field lines. The ejection of the runaway part
resulted in a very faint coronal mass ejection (CME) that propagated at an
apparent speed of 214 km s in the outer corona. The filament eruption
also triggered transverse kink-mode oscillation of the adjacent coronal loops
in the same AR. The amplitude and period of the oscillation were 1.6 Mm and 225
s. Our results are important for understanding the mechanisms of partial
filament eruptions and provide new constraints to theoretical models. The
multiwavelength observations also shed light on space weather prediction.Comment: 46 pages, 17 figures, 1 table, accepted for publication in Ap
A new approach to the derivation of dynamic information from ionosonde measurements
International audienceA new approach is developed to derive dynamic information near the peak of the ionospheric F-layer from ionosonde measurements. This approach avoids deducing equivalent winds from the displacement of the observed peak height from a no-wind equilibrium height, so it need not determine the no-wind equilibrium height which may limit the accuracy of the deduced winds, as did the traditional servo theory. This approach is preliminarily validated with comparisons of deduced equivalent winds with the measurements from the Fabry-Perot interferometer, the Millstone Hill incoherent scatter radar and with previous works. Examples of vertical components of equivalent winds (VEWs), over Wuhan (114.4° E, 30.6° N, 45.2° dip), China in December 2000 are derived from Wuhan DGS-256 Digisonde data. The deduced VEWs show large day-to-day variations during the winter, even in low magnetic activity conditions. The diurnal pattern of average VEWs is more complicated than that predicted by the empirical Horizontal Wind Model (HWM). Using an empirical electric field model based on the observations from Jicamarca radar and satellites, we investigate the contributions to VEWs from neutral winds and from electric fields at the F-layer peak. If the electric field model is reasonable for Wuhan during this period, the neutral winds contribute mostly to the VEWs, and the contribution from the E × B drifts is insignificant
Effect of supercritical carbonation on the strength and heavy metal retention of cement-solidified fly ash
This paper presents both experimental and multi-physics studies on the carbonation and heavy metal retention properties of cement-solidified fly ashes. Cement-solidified fly ash samples with 40% and 60% fly ash ratios were tested for carbonation depth after being supercritically carbonated. Tests were also carried out for compressive strength and retention capacity of heavy metals of the samples before and after supercritical carbonation. Using CO2 absorption instead of calcium carbonate to measure carbonation degree, a multi-physics model was developed and combined with a leaching model to study the impact of carbonation on Cu and Pb leaching from the cement-solidified fly ash. The results show that supercritical carbonation has both positive and negative impacts on the strength and retention capability of heavy metals of the cement-solidified fly ashes, which suggests that both the carbonation conditions and the amount of fly ash recycled in cementitious materials should be properly controlled to maximize potential positive effect
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