80 research outputs found
Dancing with wolves: how R&D human capital can benefit from coopetition
This research examines the impact of coopetition (i.e., competitor alliances) on the development of internal R&D human capital. The authors collect survey data from 111 biotech firms in Spain and US. Results show a mediation relationship: coopetition increases a firm's internal R&D human capital via its proactiveness to pursue R&D partnerships. In order to examine the mechanism behind competitor alliances, the authors investigate two moderators, alliance satisfaction and alliance coordination. The authors argue that the two factors exert opposite moderation effects on the relationship between coopetition and proactiveness to pursue R&D partnerships. Results show that when a firm and its alliance partners are satisfied with each other, the effect of coopetition on proactiveness decreases, but the moderation effect of alliance coordination, though opposite, is not significant
Lead induced structural and functional damage and microbiota dysbiosis in the intestine of crucian carp (Carassius auratus)
Lead (Pb) is a hazardous pollutant in water environments that can cause significant damage to aquatic animals and humans. In this study, crucian carp (Carassius auratus) were exposed to waterborne Pb for 96 h; then, histopathological analysis, quantitative qPCR analysis, and 16S high-throughput sequencing were performed to explore the effects of Pb on intestinal bioaccumulation, structural damage, oxidative stress, immune response, and microbiota imbalance of C. auratus. After Pb exposure, the intestinal morphology was obviously damaged, including significantly increasing the thickness of the intestinal wall and the number of goblet cells and reducing the depth of intestinal crypts. Pb exposure reduced the mRNA expressions of Claudin-7 and villin-1 while significantly elevated the level of GST, GSH, CAT, IL-8, IL-10, IL-1, and TNF-α. Furthermore, 16S rRNA analysis showed that the Shannon and Simpson indices decreased at 48 h after Pb exposure, and the abundance of pathogenic bacteria (Erysipelotrichaceae, Weeksellaceae, and Vibrionaceae) increased after Pb exposure. In addition, the correlation network analysis found that Proteobacteria were negatively correlated with Firmicutes and positively correlated with Bacteroidetes. Functional prediction analysis of bacteria speculated that the change in intestinal microbiota led to the PPAR signaling pathway and peroxisome function of the intestine of crucian carp was increased, while the immune system and membrane transport function were decreased. Finally, canonical correlation analysis (CCA) found that there were correlations between the intestinal microbiota, morphology, antioxidant factors, and immune factors of crucian carp after Pb exposure. Taken together, our results demonstrated that intestinal flora dysbiosis, morphological disruption, oxidative stress, and immune injury are involved in the toxic damage of Pb exposure to the intestinal structure and function of crucian carp. Meanwhile, Pb exposure rapidly increased the abundance of pathogenic bacteria, leading to intestinal disorders, further aggravating the damage of Pb to intestinal structure and function. These findings provide us a basis for the link between gut microbiome changes and heavy metal toxicity, and gut microbiota can be used as biomarkers for the evaluation of heavy metal pollution in future
Remote creation of strong and coherent emissions in air with two-color ultrafast laser pulses
We experimentally demonstrate generation of strong narrow-bandwidth emissions
with excellent coherent properties at ~391 nm and ~428 nm from molecular ions
of nitrogen inside a femtosecond filament in air by an orthogonally polarized
two-color driver field (i. e., 800 nm laser pulse and its second harmonic). The
durations of the coherent emissions at 391 nm and 428 nm are measured to be
~2.4 ps and ~7.8 ps respectively, both of which are much longer than the
duration of the pump and its second harmonic pulses. Furthermore, the measured
temporal decay characteristics of the excited molecular systems suggest an
"instantaneous" population inversion mechanism that may be achieved in
molecular nitrogen ions at an ultrafast time scale comparable to the 800 nm
pump pulse.Comment: 19 pages, 4 figure
High-brightness switchable multi-wavelength remote laser in air
Remote laser in air based on amplified spontaneous emission (ASE) has
produced rather well-collimated coherent beams in both backward and forward
propagation directions, opening up possibilities for new remote sensing
approaches. The remote ASE-based lasers were shown to enable operation either
at ~391 and 337 nm using molecular nitrogen or at ~845 nm using molecular
oxygen as gain medium, depending on the employed pump lasers. To date, a
multi-wavelength laser in air that allows for dynamically switching the
operating wavelength has not yet been achieved, although this type of laser is
certainly of high importance for detecting multiple hazard gases. In this
Letter, we demonstrate, for the first time to our knowledge, a harmonic-seeded
switchable multi-wavelength laser in air driven by intense mid-infrared
femtosecond laser pulses. Furthermore, population inversion in the
multi-wavelength remote laser occurs at an ultrafast time-scale (i.e., less
than ~200 fs) owing to direct formation of excited molecular nitrogen ions by
strong-field ionization of inner-valence electrons, which is fundamentally
different from the previously reported pumping mechanisms based either on
electron recombination of ionized molecular nitrogen or on resonant two-photon
excitation of atomic oxygen fragments resulting from resonant two-photon
dissociation of molecular oxygen. The bright multi-wavelength laser in air
opens the perspective for remote detection of multiple pollutants based on
nonlinear spectroscopy.Comment: 18 pages, 5 figure
Impulsive rotational Raman scattering of N2 by a remote "air laser" in femtosecond laser filament
We report on experimental realization of impulsive rotational Raman
scattering from neutral nitrogen molecules in a femtosecond laser filament
using an intense self-induced white-light seeding "air laser" generated during
the filamentation of an 800 nm Ti: Sapphire laser in nitrogen gas. The
impulsive rotational Raman fingerprint signals are observed with a maximum
conversion efficiency of ~0.8%. Our observation provides a promising way of
remote identification and location of chemical species in atmosphere by
rotational Raman scattering of molecules.Comment: 4 pages, 4 figure
Generation of Kerr soliton microcomb in a normally dispersed lithium niobate microdisk resonator by mode trimming
Anomalous microresonator dispersion is mandatory for Kerr soliton microcomb
formation, which depends critically on the geometry of the microresonator and
can hardly be tuned after the structure is made. To date, cavity-based
microcombs have only been generated with fundamental whispering gallery modes
(WGMs) of anomalous dispersion in microresonators. Moreover, microcomb
generation in highly Raman-active platforms such as lithium niobate (LN)
microresonators frequently suffers from stimulated Raman scattering and mode
crossing due to the existence of multiple families of high-order WGMs. Here, we
reveal a unique Kerr soliton microcomb generation mechanism through mode
trimming in a weakly perturbed LN microdisk resonator. Remarkably, the soliton
comb is generated with fundamental WGMs of normal dispersion and free from the
mode crossing and Raman scattering effects. A robust soliton with a spectrum
spanning from 1450 nm to 1620 nm at an on-chip pump power of 35 mW. Our
discovery offers a powerful solution to circumvent the stringent requirements
on high-precision dispersion engineering and termination of Raman excitation
for soliton generation in the high-Q microdisk.Comment: 16 pages,and 5 figure
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