Holocene dust storm variations over northern China: transition from a natural forcing to an anthropogenic forcing

Asian dust storms have long been a major environmental concern in China, affecting the lives of about one billion people. However, it is unclear whether the mechanisms responsible for Asian dust storms during the Holocene varied on different timescales, and thus it is unclear whether there was a shift from a natural forcing to an anthropogenic forcing of dust storms. We reconstructed a high-resolution Holocene record of dust storms from the sediments of an undisturbed alpine lake on the Chinese Loess Plateau. We found that Asian dust storm activity generally increased during the Holocene, with the largest fluctuations occurring during the past 2000 years. The increase in dust storm activity was in contrast to the decrease in East Asian winter monsoon (EAWM) intensity during the Holocene, indicating that the EAWM played a limited role in modulating dust storms. By contrast, the increase in dust storms corresponded to a decrease in EASM precipitation. This demonstrates that EASM precipitation was the dominant control of dust storm activity on a millennial timescale, because decreased EASM precipitation expanded the desert area and thus increased the dust storm activity. The increasing intensity of human activity in the region since the Bronze Age resulted in an acceleration of dust storm activity against the background of decreased EASM precipitation. As human disturbance continued to intensify, beginning at least at ~2 cal ka BP, increased dust storms were closely linked to increasing human populations in the dust source regions, and there is a strong temporal coherence between increased dust storms and higher EASM precipitation. This was completely different from when natural processes are dominant. During that period, fewer dust storms occurred during periods of a strengthened EASM. Therefore, there was a shift from a natural forcing to an anthropogenic forcing of dust storms on a multi-decadal to centennial timescale, and was a mode in which "human activity overtook the EASM as the dominant control of the Earth surface system".

Comparison of plain radiography and CT in postoperative evaluation of ankle fractures

AIM

To compare postoperative plain radiographs with computed tomography (CT) post-processing images in evaluating the quality of anatomical reduction and internal fixation of ankle fractures.

MATERIALS AND METHODS

A total of 168 patients who sustained closed ankle fracture and were treated with open reduction and internal fixation in East Hospital were reviewed. Postoperative plain radiographs and CT post-processing images were evaluated. The observation was performed under volume-rendering mode and multiplanar reconstruction mode. The assessment was performed by two independent orthopaedic surgeons. The inter- and intra-observer variations were analysed by kappa statistics. The differences between plain radiographs and CT post-processing images were compared using χ(2) test (McNemar's test).

RESULTS

Inter- and intra-observer agreement was almost perfect (0.813-1.000) using CT post-processing images, which was higher than that using plain radiographs (0.323-0.848). More non-anatomical reduction could be recognised in the supination-external rotation (SER), supination-adduction (SAD), pronation-external rotation (PER), and overall groups (p<0.05) and more poor internal fixation could be recognised in the SER, SAD, and overall groups (p<0.05) using CT post-processing images than using radiographs.

CONCLUSION

More residual articular step, fracture fragment displacement, and poor internal fixation could be detected by CT post-processing images than plain radiographs.

Structure and expression of the Aplysia polyubiquitin gene

The ubiquitin-proteasome pathway, which is up-regulated in response to sensitizing treatments with serotonin (5-HT), plays a critical role in inducing long-term facilitation (LTF) of sensory-to-motor synapses in Aplysia. We characterized the structure of the polyubiquitin gene of Aplysia and studied its expression. At least six ubiquitin coding units exist in tandem, one of which encodes a protein with an amino acid sequence identical to human ubiquitin. Although the synthesis of polyubiquitin is induced by strong stimuli in many organisms, we found that the expression of ubiquitin in Aplysia is not affected by protocols that produce LTF.

Effect of nitric oxide synthesis inhibition on c-Fos expression in hippocampus and cerebral cortex following two forms of learning in rats: an immunohistochemistry study

This study investigated the effect of NO on c-Fos expression using immunocytochemical techniques, following training in the one-trial passive avoidance response and Morris water maze tasks. Fos-like immunoreactive (FLI) neurons were examined in the hippocampus and cerebral cortex of rats in which intracerebroventricular (i.c.v.) injection of Nomega-nitro-L-arginine (NAME) was given 30 min before training in the experimental groups. The results showed that: (1) when compared with untreated rats or rats receiving i.c.v. saline injection, fos-like immunoreactive neurons were significantly increased in both brain regions following training in either task, and (2) preceding i.c.v. injections of NAME blocked both the formation of memory and the increased expression of c-Fos in both brain regions subjected to training on the two models. These results suggest that NO production may be a critical factor for the formation of memory and the enhanced c-Fos expression, and so might contribute to the long-term plasticity of synaptic organization in the two brain regions.

Nociceptive c-fos expression in supraspinal areas in avoidance of descending suppression at the spinal relay station

The number and distribution of Fos-like-immunoreactive neurons in different supraspinal brain areas induced by formalin injection into one hindpaw was estimated in rats with transected dorsal half of the spinal cord at the thoracic level in an attempt to avoid most of the descending modulatory actions. The results showed that: (i) after spinal lesion, the peripheral noxious inputs, going up mainly through the ventral spinal cord, elicited a more widespread and densely located Fos-like-immunoreactive neurons in subcortical areas, many of them showed no Fos expression when noxious stimulation was given in rats with intact spinal cord; (ii) at the same time, a small number of subcortical areas, such as the lateral ventroposterior thalamic nucleus and dorsal raphe nucleus, exhibited no significant increase of nociceptive Fos-like immunoreactive neurons after spinal lesion as compared to that with intact spinal cord; and (iii) there appeared a prominent expansion of cortical areas with densely located Fos-like-immunoreactive neurons in spinal-lesioned rats as compared with the limited labelled areas in the control group with intact spinal cord. These results indicate that: (i) in avoiding the spinally descending modulatory mechanisms, more widespread supraspinal and cortical neurons will be recruited and activated in response to the noxious stimulation; and (ii) the descending systems exert differential actions on the spinal targets which project nociceptive signals to different supraspinal regions. The implication of these facts is discussed.

Nitric oxide is involved in the formation of learning and memory in rats: studies using passive avoidance response and Morris water maze task

The study was designed to test whether blockade of endogenous NO production affects learning and memory formation in rats. The rats received an intracerebroventricular (i.c.v.) injection of the inhibitor of nitric oxide synthase, N omega-nitro-L-arginine (NAME), 30 min before each training, and were then tested in the one-trial passive avoidance response and Morris water maze task, respectively. The results showed that: (1) among four concentrations of drug used, only doses higher than 3 mumol of i.c.v. NAME impaired learning and memory formation significantly (p < 0.05) in both test models; (2) in Morris water maze task, the animals treated with highest dose of NAME (5 mumol) failed to learn while those treated with lower doses succeeded; (3) in Morris water maze task, the i.c.v. NAME, even in higher doses, did not affect the capacity of finding a visible platform. It is suggested that NO is involved in learning and memory formation by potentiating or facilitating mainly the acquisition process.

[Three-dimensional echocardiography in evaluation of left ventricular systolic function after mitral valve replacement for chronic mitral diseases with preservation of mitral apparatus]

OBJECTIVE

To assess the global left ventricular performance in 24 normal subjects, 24 patients suffered from mitral valve disease (MVD) with mitral valve replacement (MVR), and 20 patients with mitral valve replacement with preservation of mitral apparatus (MVRP).

METHODS

3DE was used in comparion with the findings of radiography (RNA), two-dimensional echocardiography (2DE), and m-mode (MME).

RESULTS

EF in 10 patients with MVD as compared with RNA, 3DE showed a higher connection coefficient than 2DE and MME. The EF estimated by MME and 2DE showed no difference between NS and MVD groups, there were significant differences when compared with those examined by 3DE. Two, three months after opertion, the VED and VES in group of MVRP were significantly lower than those in group of MVR (P < 0.01), the EF of MVRP group was remarkably higher than that of MVR group (P < 0.05).

CONCLUSION

3DE has the ability to estimate the EF of left ventricle more accurately than 2DE and MMe, especially in the patients suffered from chronic MVD with LV shape deformation. The MVR with preservation of mitral apparatus for chronic MVD is beneficial to maintaining the global systolic function after surgery.

[Clinical fracture of joint prostheses]

Ten Ti6Al4V joint prostheses, including 8 hips and 2 knees, were fractured after 1 to 13 years in vivo service following the primary arthroplasty. The metallographs and electronic microscopies, taken from the retrieved components, demonstrated that there are typical characteristics of stress corrosion fatigue. The excessive chemical content of raw material, the presence of interior defects, such as inclosures and porosities, incorrect design features, which violate biomechanic principles, the overheating and improper surface finishing of the parts, and the clinical varus positioning of the hip stem contribute to the device failure. Policies are proposed to overcome this problem. Among them are drawing national mandatory standards on surgical implants, taking strigent administration measures to ensure the quality of joint prostheses and the establishment of training centers for arthroplasty.

[A logistic regression analysis of relations between juvenile myopia and TV-watching, trace elements, and psychological characteristics]

With a paired study, 23 factors were investigated in 204 school children aged 9-14 in Taiyuan. The results of analysis of logistic regression showed that there was a close relationship between juvenile myopia and TV-watching distance, myopia in parents, Zn: Cu ratio in hair, N score of EPQ, Pscore of EPQ, and verbal IQ. The relations between myopia and some factors were discussed.