Estimation of fixed effects spatial dynamic panel data models with small T and unknown heteroskedasticity

Ministry of Education, Singapore under its Academic Research Funding Tier

What Causes the Divestment of Multinational Companies in China? A Subsidiary Perspective

This paper examines the causes of MNCs’ divestments in China. The MNCs’ profitability, market shares and productivities are negatively related to the possibility of divestment, while the MNCs’ debts are positively related to the possibility that foreign investments are divested. These results suggest that divestments are affected by MNCs’ performances, and their performances are endogenous shocks for divestment

Increasing autophagy does not affect neurogenic muscle atrophy

Physiological autophagy plays a crucial role in the regulation of muscle mass and metabolism, while the excessive induction or the inhibition of the autophagic flux contributes to the progression of several diseases. Autophagy can be activated by different stimuli, including cancer, exercise, caloric restriction and denervation. The latter leads to muscle atrophy through the activation of catabolic pathways, i.e. the ubiquitin-proteasome system and autophagy. However, the kinetics of autophagy activation and the upstream molecular pathways in denervated skeletal muscle have not been reported yet. In this study, we characterized the kinetics of autophagic induction, quickly triggered by denervation, and report the Akt/mTOR axis activation. Besides, with the aim to assess the relative contribution of autophagy in neurogenic muscle atrophy, we triggered autophagy with different stimuli along with denervation, and observed that four week-long autophagic induction, by either intermitted fasting or rapamycin treatment, did not significantly affect muscle mass loss. We conclude that: i) autophagy does not play a major role in inducing muscle loss following denervation; ii) nonetheless, autophagy may have a regulatory role in denervation induced muscle atrophy, since it is significantly upregulated as early as eight hours after denervation; iii) Akt/mTOR axis, AMPK and FoxO3a are activated consistently with the progression of muscle atrophy, further highlighting the complexity of the signaling response to the atrophying stimulus deriving from denervation

A CFD study of IGV vane number on hydraulic characteristics and pressure pulsation of an is centrifugal pump

Vane number is an important parameter of IGV device, which indirectly affects hydraulic performance and pressure pulsation characteristics of the attached pump. In this study, based on an IS pump, the influences of vane number on hydraulic performance and pressure pulsation characteristics were considered. Four set of IGV devices were generated to assemble to the pump with 5, 6, 7 and 9 vanes, respectively. Then the three-dimensional unsteady flow fields were simulated using RNG k-ε turbulence model and sliding mesh by Fluent-16.0. The numerical results showed good agreement with the experimental data, which validated the numerical models. The effects of vane number on pump head and efficiency are different. 6 vanes IGV device can produce higher head while 7 or 9 vanes can bring about higher efficiency. Similarly, the influences of vane number on pressure pulsation in time domain and frequency domain are also complex. 6 vanes IGV device can remarkably decrease power spectral density at all flow rate conditions, but 7 vanes IGV device can improve pump pressure pulsation characteristics and realize better hydraulic stability. Therefore, it is hard to determine the best vane number, but 6 vanes IGV device is suggested for engineering application to obtain better hydraulic performance

A rare tentorial mesenchymal chondrosarcoma in posterior cranial fossa: Case report

Intracranial extraskeletal mesenchymal chondrosarcoma is a very rare malignant tumor with predilection site of frontoparietal falx cerebri. Only few cases of mesenchymal chondrosarcoma in posterior cranial fossa are reported. Here, we report a 23-year-old young man with a dura-attached mass in left posterior cranial fossa misdiagnosed as a tentorial meningioma preoperatively. According to the following operation, the lesion was confirmed as mesenchymal chondrosarcoma surgically and pathologically. On MRI, the tumor was characterized by lobulated soft-tissue mass with dura-attached base, patchy calcifications and heterogeneous signal intensities. On contrast-enhanced MRI, it was well-defined, with marked enhancement. We consider that these imaging features above might remind us to consider the diagnosis of mesenchymal chondrosarcoma in posterior cranial fossa. The postoperative treatment of radiotherapy is still controversial. As for our case, according to the 24 months follow-up after postoperative γ-knife, our patient shows an optimistic prognosis so far

The mechanical stimulation of myotubes counteracts the effects of tumor-derived factors through the modulation of the activin/follistatin ratio

Activin negatively affects muscle fibers and progenitor cells in aging (sarcopenia) and in chronic diseases characterized by severe muscle wasting (cachexia). High circulating activin levels predict poor survival in cancer patients. However, the relative impact of activin in mediating muscle atrophy and hampered homeostasis is still unknown. To directly assess the involvement of activin, and its physiological inhibitor follistatin, in cancer-induced muscle atrophy, we cultured C2C12 myotubes in the absence or in the presence of a mechanical stretching stimulus and in the absence or presence of C26 tumor-derived factors (CM), so as to mimic the mechanical stimulation of exercise and cancer cachexia, respectively. We found that CM induces activin release by myotubes, further exacerbating the negative effects of tumor-derived factors. In addition, mechanical stimulation is sufficient to counteract the adverse tumor-induced effects on muscle cells, in association with an increased follistatin/activin ratio in the cell culture medium, indicating that myotubes actively release follistatin upon stretching. Recombinant follistatin counteracts tumor effects on myotubes exclusively by rescuing fusion index, suggesting that it is only partially responsible for the stretch-mediated rescue. Therefore, besides activin, other tumor-derived factors may play a significant role in mediating muscle atrophy. In addition to increasing follistatin secretion mechanical stimulation induces additional beneficial responses in myotubes. We propose that in animal models of cancer cachexia and in cancer patients purely mechanical stimuli play an important role in mediating the rescue of the muscle homeostasis reported upon exercise