[Imaging features of developmental stenosis of atlas with degenerative cervical myelopathy].

Objective: To investigate the imaging features of patients with developmental stenosis of atlas (small atlas) complicated with degenerative cervical myelopathy and to explore the diagnostic criteria of small atlas. Methods: The clinical data of patients with degenerative cervical myelopathy treated by posterior cervical laminoplasty and resection of posterior arch of atlas from 2006 to 2020 in the Department of Orthopedics, Peking University Third Hospital were retrospectively analyzed. Sixteen cases had spinal cord compression at C1 level after the exclusion of ossification of cervical posterior longitudinal ligament (OPLL) and other pathology. These cases were suspected small atlas (small atlas group). Forty-six cases without posterior arch resection in the same period were selected as control group. The middle sagittal diameter of atlas and the vertical distance from posterior tubercle of atlas to occipitoaxial line under CT in both groups were compared. The sagittal diameter of the spinal canal at the atlas level under MRI, the Japanese Orthopaedic Association (JOA) score for functional state of cervical spine before operation and at last follow-up were also measured. Results: There were 9 males and 7 females in the small atlas group, aged (63±12) years. There were 21 males and 25 females in the control group, aged (57±10) years. The patients in both group were followed-up for at least one year. The sagittal diameter of atlas in the small atlas group was (26.4±3.1) mm, which was significantly smaller than that in the control group [(29.6±2.2) mm, P=0.010]. The vertical distance from the posterior tubercle of atlas to the occipitoaxial line in the small atlas group was larger than that in the control group[(6.79±1.17) mm vs (5.57±1.29) mm, P=0.001]. The diameter of atlas canal in the small atlas group was (8.25±1.44) mm which was significantly smaller than that in the control group [(13.00±1.66) mm, P<0.001]. The JOA score of the small atlas group before operation and at the last follow-up were both slightly lower than that in the control group (both P<0.05), but there was no significant difference in the recovery rate of JOA score between the two groups (61.9% vs 66.0%, P=0.066). Among the 16 cases in the small atlas group, 5 cases of occipital-axial connection were located at the posterior 1/3 of the posterior arch of atlas, and 11 cases of occipital-axial connection were completely located at the posterior arch of atlas. Conclusions: The effective sagittal diameter of atlas is smaller in small atlas group which can lead to more severe cervical myelopathy. The presence of a small atlas should be highly suspected when the sagittal diameter of atlas canal is less than 26 mm under CT. The existence of the small atlas should be alert when the occipitalaxial line is located at the dorsal 1/3 or behind of the posterior arch of atlas.

Impacts of international food and feed trade on nitrogen balances and nitrogen use efficiencies of food systems.

International trade of agricultural products has greatly increased over time, but its impacts on sustainable development are debated. It may contribute to food security in importing countries, increases the dependency between countries, and has been implicated in displacement of environmental pollution and resource depletion. There is also discussion about the relationships between trade and nitrogen (N) balances and N use efficiencies (NUE). We explored relationships between changes in the trade of food and feed and in N balances and NUE of the food supply systems through simulation modeling and an analysis of empirical data of 115 countries (representing 91% of global population) for the period 1961-2011. In the empirical analysis, 64 main importing countries and 14 main exporting countries, were distinguished. Importing countries had on average a higher population density than exporting countries but rather similar protein intake and GDP per capita. The empirical analysis indicate that main importing countries had on average higher N fertilizer inputs to their food supply systems, and also higher N surpluses and higher NUE than main exporting countries. The overall mean NUE of the food supply system of main importing countries decreased with increasing import, but the relationships between import and NUE were diverse when these countries were grouped according to population density and GDP per capita. We compared N balances and partial N balances, and three methodologies commonly used for estimating NUE. We observed that NUE2 provides an unbiased estimate for both importing and exporting countries. Our study contributes to the understanding of the diverse relationships between international trade, N balances and NUE of food systems.

Direct Measurement of the Astrophysical

Fluorine is one of the most interesting elements in nuclear astrophysics, where the ^{19}F(p,α)^{16}O reaction is of crucial importance for Galactic ^{19}F abundances and CNO cycle loss in first generation Population III stars. As a day-one campaign at the Jinping Underground Nuclear Astrophysics experimental facility, we report direct measurements of the essential ^{19}F(p,αγ)^{16}O reaction channel. The γ-ray yields were measured over E_{c.m.}=72.4-344 keV, covering the Gamow window; our energy of 72.4 keV is unprecedentedly low, reported here for the first time. The experiment was performed under the extremely low cosmic-ray-induced background environment of the China JinPing Underground Laboratory, one of the deepest underground laboratories in the world. The present low-energy S factors deviate significantly from previous theoretical predictions, and the uncertainties are significantly reduced. The thermonuclear ^{19}F(p,αγ)^{16}O reaction rate has been determined directly at the relevant astrophysical energies.

[Evaluation of safety of two inactivated COVID-19 vaccines in a large-scale emergency use].

Objective: To evaluate the safety of two inactivated COVID-19 vaccines in a large-scale emergency use. Methods: Based on the "Vaccination Information Collection System", the incidence data of adverse reactions in the population vaccinated with the inactivated COVID-19 vaccines developed by Beijing Institute of Biological Products Co., Ltd and Wuhan Institute of Biological Products Co., Ltd, respectively, in emergency use were collected, and the relevant information were analyzed with descriptive epidemiological and statistical methods. Results: By December 1, 2020, the vaccination information of 519 543 individuals had been collected. The overall incidence rate of adverse reactions was 1.06%, the incidence rate of systemic adverse reactions was 0.69% and the incidence rate of local adverse reactions was 0.37%. The main systemic adverse reactions included fatigue, headache, fever, cough and loss of appetite with the incidence rates of 0.21%, 0.14%, 0.06%, 0.05% and 0.05%, respectively; the main local adverse reactions were injection site pain and injection site swelling with the incidence rates of 0.24% and 0.05%, respectively. Conclusion: The two inactivated COVID-19 vaccines by Beijing Institute of Biological Products Co., Ltd and Wuhan Institute of Biological Products Co., Ltd showed that in the large-scale emergency use, the incidence rate of general reactions was low and no serious adverse reactions were observed after the vaccinations, demonstrating that the vaccines have good safety.

[Quantitative analysis of the degeneration of cervical spine and the correlation to the heterotopic ossification after artificial cervical disc replacement].

Objective: To investigate parameters related to quantifying the amount of degeneration in preoperative patients to identify ideal indication of artificial cervical disc replacement (ACDR) in patient with a minimum of 10 years of follow-up data. Methods: From January 2004 to August 2008, a total of 44 patients underwent single level Bryan cervical disk replacement performed by the same group of surgeons were involved in this retrospective study, and all of the patients in this group had at least 10 years of follow-up data. Heterotopic ossification (HO) was graded in radiographic images by using the McAfee classification. Preoperative degeneration of cervical spine was evaluated in radiographs based on a quantitative"9 points"scoring system. Univariate analysis and multifactor logistic regression were made to identify significant factors. To determine the cut-off points for the significant factors, a receiver operating characteristic (ROC) curve analysis was conducted. Results: The incidence of HO in study group was 61.4%. Based on univariate analysis results, there were significant differences in the scores of disc height, the presence of anterior osteophytes and endplate sclerosis between the HO group and non-HO group (all P<0.05), and the indices were included in the multivariate analysis. According to the logistic regression results, disc height and endplate sclerosis were identified as the independent risk factors for HO(OR(95%CI): 10.801(1.202-97.064), 37.870(1.581-907.237), respectively, both P<0.05). ROC analysis showed the area under the curve (AUC) of disc height and endplate sclerosis were 0.822 and 0.792, respectively. According to the scoring system, the ROC curve indicated that both the optimal cutoff points were 1.5. Conclusion: The incidence of postoperative HO is relatively high among the patients who had more than 10 years follow-up, and the amount of degeneration in the target level before surgery correlated with the incidence of HO.

[The correlation between the severity of uncovertebral joints degeneration and heterotopic ossification after single-level artificial cervical disc replacement].

Objective: To investigate the correlation between the severity of uncovertebral joints degeneration and heterotopic ossification (HO) after single-level artificial cervical disc replacement (ACDR). Methods: From January 2005 to January 2016, 70 patients who had undergone single-level ACDR in Peking University Third Hospital and had at least 5 years follow-up were included in this study. There were 35 males and 35 females with an average age of (42±8) years (range, 25-62 years). Cervical spine A-P X-rays were taken to assess the degeneration of uncovertebral joints and lateral X-rays were taken to assess the degeneration of intervertebral space. Cervical spine lateral and the flexion-extension X-rays at 5 years follow up were taken to assess HO. Degeneration of uncovertebral joints were evaluated by the classification system set-up in Peking University Third Hospital. Kellgren&Lawrence grading system was used to evaluate the degeneration of intervertebral space. HO was evaluated by the McAfee grading standards. The data were collected before surgery and at 5-years follow-up, then the correlation between degeneration of uncovertebral joints, degeneration of intervertebral space and HO was analyzed with Spearman non-parametric test. Results: The average follow-up time of 70 patients was (62.7±4.8) years (range, 52-74 months). There was a significant positive correlation between preoperative uncovertebral joints degeneration and HO after ACDR (r=0.585, P<0.01). There was a significant positive correlation between preoperative intervertebral space degeneration and HO (r=0.557, P<0.01). There was a significant positive correlation between preoperative intervertebral space degeneration and preoperative uncovertebral joints degeneration (r=0.727, P<0.01). Conclusion: There is a significant positive correlation between preoperative uncovertebral joints degeneration and HO after ACDR.

Environmental impacts of nitrogen emissions in China and the role of policies in emission reduction.

Atmospheric reactive nitrogen (Nr) has been a cause of serious environmental pollution in China. Historically, China used too little Nr in its agriculture to feed its population. However, with the rapid increase in N fertilizer use for food production and fossil fuel consumption for energy supply over the last four decades, increasing gaseous Nr species (e.g. NH3 and NOx) have been emitted to the atmosphere and then deposited as wet and dry deposition, with adverse impacts on air, water and soil quality as well as plant biodiversity and human health. This paper reviews the issues associated with this in a holistic way. The emissions, deposition, impacts, actions and regulations for the mitigation of atmospheric Nr are discussed systematically. Both NH3 and NOx make major contributions to environmental pollution but especially to the formation of secondary fine particulate matter (PM2.5), which impacts human health and light scattering (haze). In addition, atmospheric deposition of NH3 and NOx causes adverse impacts on terrestrial and aquatic ecosystems due to acidification and eutrophication. Regulations and practices introduced by China that meet the urgent need to reduce Nr emissions are explained and resulting effects on emissions are discussed. Recommendations for improving future N management for achieving 'win-win' outcomes for Chinese agricultural production and food supply, and human and environmental health, are described. This article is part of a discussion meeting issue 'Air quality, past present and future'.

[Surgical treatment of severe congenital cervical kyphosis].

Objective: To investigate the surgical treatment of severe congenital cervical kyphosis. Methods: The clinical data of patients with severe congenital cervical kyphosis (Cobb>40°) treated in Peking University Third Hospital from March 2004 to March 2018 were retrospectively summarized. In this series, 8 cases were enrolled, included 4 males and 4 females; the patients were 5-45 years old. According to the etiology, 4 patients were diagnosed with vertebral body underdevelopment, 2 with vertebral insufficiency, 1 with cervical spine congenital fusion and 1 with C(2) spinous process mecism. Five cases were treated with traction before final surgical correction. The surgical strategy was anterior correction or posterior correction or combined procedure in regards to different situation. The curvature of cervical angle was measured by two-line Cobb method, and the cervical kyphosis angle was measured on lateral radiographs in the neutral and extended position at the pre-operation and post-operation in each patient. The correction rate and evaluated Japanese Orthopedic Association (JOA) scoring for the function of spinal cord were also measured. The data before and after the operation were compared with t test. Results: In this series, the average kyphotic Cobb angle was 67°±18° and 8°±8° before and after surgical correction, respectively (t=8.471,P<0.05).The final correction rate was 87%±13%.The JOA score improved from 11.1±2.7 to 14.0±1.5 (t=-2.656, P<0.05) at the end of follow up. Conclusions: The pre-correction by cervical spine traction and final surgical correction by anterior, posterior or combined approaches of internal fixation and fusion can achieve good results and reduce risk and difficulty in operation for severe congenital cervical spine kyphosis with vertebral body underdevelopment without vertebral insufficiency and cervical spine congenital fusion. The final surgical correction by one-stage anterior, posterior or combined approaches of internal fixation and fusion can achieve good results for severe congenital cervical spine kyphosis with vertebral insufficiency and/or cervical spine congenital fusion.

[Detection of circulating tumor DNA in epidermal growth factor receptor-TKI relapsed non-small cell lung cancer patients using next-generation sequencing and an analysis of the resistant mechanisms].

Objective: Next-generation sequencing (NGS) was performed on circulating tumor DNA (ctDNA) samples from tyrosine kinase inhibitor (TKI)-naïve non-small cell lung cancers (NSCLC) and TKI-relapsed NSCLC to investigate the clinical value. Methods: A total of 381 plasma samples from patients who were diagnosed with lung cancer in Cancer Hospital Chinese Academy of Medical Sciences from March 2017 to May 2018 were enrolled in the study. NGS was performed using a custom-designed panel that covers 10 lung cancer-related driven genes. Paired plasma-tissue samples from 39 patients were collected to analyses the sensitivity and specificity of detecting driver gene mutations using ctDNA. NGS was also performed on plasma samples from TKI-relapsed patients to identify TKI resistance mechanisms. Results: Thirty-nine plasma samples collected from 39 NSCLC patients (including 21 female and 18 male) with corresponding tissue biopsies were analyzed for the sensitivity and specificity. The average age was 56 years (range 29 to 82 years). A high concordance of 84.62% (33/39) was observed between ctDNA and tissue biopsies. Compared with tissue biopsies, NGS sensitivity for ctDNA was 82.14% and specificity was 90.91%.Among these 39 patients, 34 were advanced stage patients (III-IV stage). The concordance, sensitivity, and specificity for ctDNA among the advanced stage patients were 88.24% (30/34), 86.36% (29/34) and 91.67% (31/34), respectively. Among the 381 plasma samples [including 231 TKI-naïve patients and 150 epithelial growth factor receptor(EGFR)-TKI relapsed patients], EGFR mutation was the most common driver gene among the 221 TKI-naïve lung adenocarcinoma patients (32.58%, 72/221). For 133 patients who progressed after first-generation EGFR-TKI, T790M was found to be the most frequent resistant mechanism (39.10%, 52/133), as well as bypass activation (3.01%, 4/133; such as MET amplification and ERBB2 amplification). Among those first-generation EGFR-TKI relapsed patients with EGFR sensitive mutations, T790M was detected in 53.06% (52/98). For the 17 patients who progressed after third-generation EGFR-TKI, C797S was found to be the most common resistant mechanism (4/17). Conclusions: The concordance, sensitivity and specificity between ctDNA and tissue biopsies are acceptable. ctDNA analysis provides valuable information for lung cancer patients' targeted treatment, especially for patients not fitted for biopsies.

[Midterm clinical outcomes and radiological results of surgical treatment for Hirayama disease].

OBJECTIVE: To assess the midterm clinical and radiological outcomes of internal fixation and fusion for the treatment of Hirayama disease and to evaluate the clinical significance and value of this procedure. METHODS: In the study, 36 patients were treated with anterior cervical internal fixation and fusion. The clinical outcomes including muscle strength and atrophy were recorded. The radiological outcomes including range of motion of cervical spine and the cross-sectional area of spinal cord at each level on MRI scan were measured before and at 3 month, 1 year and 2 years follow-up time points after surgery. RESULTS: (1) Clinical outcomes: all the patients showed no further progression of symptoms except one patient with mild progression of muscular weakness and atrophy. As the time passed by, the ratio of the patients with muscle strength and atrophy improvement increased. There were 26.5% of patients in 3 months, 36.0% in 1 year and 85.7% in 2 years who experienced muscle strength improvement. 8.8% of patients in 3 months, 24.0% in 1 year and 35.8% in 2 years felt muscle atrophy improvement. And 12 of the 14 patients showed improved muscle strength and atrophy at the end of 2 years period follow-up. (2) Radiological outcomes: the range of motion (ROM) of C2-C7 was significantly decreased after the operation. The ROM of preoperation was 62.25°±2.10° and that of 2 years postoperation was 13.67°±7.51°(P<0.01). The spinal cord was of no compression on flexion MRI. The cross-section area of spinal cord on MRI was significantly increased only at C6 level (P<0.05) at the end of three months follow-up. The level of increased cross-section area rose to C4-C5-C6 levels (P<0.01) in 1 year and to C4-C5-C6-C7 levels at the end of 2 years follow-up (P<0.05). The cross-section area increased 15.60% at C4, 19.08% at C5, 21.60% at C6 and 23.91% at C7 with significant difference (P<0.05) 2 years after the operation. CONCLUSION: Anterior cervical internal fixation and fusion is an effective surgical treatment for Hirayama disease and may provide preferable midterm clinical and radiological outcomes. This procedure has clinical significance and value in terms of control of the progression and outcome of this disease.

[Effects of percutaneous nephrolithotomy in the treatment of medullary sponge kidney with calculi].

Objective: To evaluate the effects of percutaneous nephrolithotomy (PNL) in the treatment of medullary sponge kidney with calculi. Methods: A total of 77 patients (91 renal units) of medullary sponge kidney with calculi (MSK group) and 77 patients (77 renal units) with common kidney stone (control group) received PNL at Department of Urology in Peking University People's Hospital from September 2006 to February 2016 were analyzed retrospectively. The MSK group included 33 males and 44 females with a mean age of (42.1±13.2) years, the mean stone burden was (3.9±1.8) cm. The control group included 36 males and 41 females with a mean age of (45.3±13.0) years, the mean stone burden was (3.6±1.5) cm. The numbers of tracts, the time of operation, the drop of hemoglobin, the change of creatine, the time of hospitalization, the stone free rate and major complications were compared between the two groups. The measurement data and numeration data were compared with t test and χ(2) test. Results: There were no significant differences in sex, age, preoperative urinary tract infection, stone type, and stone burden between the two groups (all P>0.05). The proportion of bilateral renal calculus in MSK group was higher (18.2% vs. 0, χ(2)=15.400, P=0.000). There were 159 percutaneous channels were established in MSK group while 90 percutaneous channels were established in control group. Compared with the control group, the operation time ((88.1±37.5) minutes vs. (68.5±30.1) minutes, t=3.543, P=0.000) and hospitalization time ((15.1±8.3) days vs. (10.1±3.6) days, t=4.816, P=0.000) were longer, the creatinine level increased ((101.2±62.6) µmol/L vs. (71.3±23.6) µmol/L, t=3.777, P=0.000), the rate of stone free decreased (27.5% vs. 83.1%, χ(2)=51.840, P=0.000) and the rate of complications increased (29.9% vs. 11.7%, χ(2)=8.114, P=0.004) in MSK group. There was no statistically difference in hemoglobin drop ((12.5±13.2) g/L vs. (13.0±10.9) g/L, t=-0.260, P=0.795). Conclusions: Using PNL for patients of MSK with calculi has a lower stone free rate and a higher complications. It is an effective method for patients of MSK with large and complex calculi.

[Reoperation for cervical myelopathy duo to progressing ossification of the posterior longitudinal ligaments in patients with expansive laminoplasty].

OBJECTIVE: To retrospectively analyze the clinical data of the patients with reoperation for cervical myelopathy due to progressing ossification of the posterior longitudinal ligaments, with previous open-door expansive laminoplasty, and to evaluate the outcomes. METHODS: From May 2006 to July 2012, a retrospective study was performed on a consecutive series of 17 patients with previous open-door expansive laminoplasty, who had received the reoperation for cervical myelopathy due to progressing ossification of the posterior longitudinal ligaments. The reoperation was performed based on the clinical manifestations and segments of responsibility. The anterior approaches were performed in 12 cases, and the posterior approaches in 5 cases. The correlation between the clinical factors and Japanese Orthopedic Association (JOA) scores or the JOA recovery rate was evaluated by Pearson or Spearman correlation test. The pre- and post-operative JOA scores were analyzed by repeated measures ANOVA and the JOA recovery rates were compared with paired t test. RESULTS: The mean follow-up was 137.5 months (range 60-348 months). There were no serious complications after surgical procedures. There was one case that had C5 palsy in the first operation and had recovery after one week. Another case had C5 palsy in the reoperation with posterior approach, which had recovery at the end of 6 months postoperation. Three cases had the cerebrospinal fluid leakage of the reoperation, with two cases in the anterior approaches and one case in the posterior approach. There was no significant correlation between the clinical variables and JOA scores or JOA recovery rates. The JOA scores of the patients in the first operation were improved from 9.4±4.1 to 12.8±2.8 (P<0.01), and the JOA recovery rate was 45.6%. The JOA scores of the reoperation were improved from 10.2±2.8 to 12.7±2.4 (P<0.05) at the end of 6 months and 14.3±1.9 (P<0.01) by the last follow-up. There were significant differences between the JOA recovery rates by the last follow-up (63.2%) and at the end of 6 months (39.3%) of the reoperation or 45.6% of the first operation (P<0.01). CONCLUSION: The reoperation for cervical myelopathy duo to progressing ossification of the posterior longitudinal ligaments can significantly promote the recovery of the spinal cord, based on the clinical manifestations combined with segments of responsibility of the imaging.

Changes in pig production in China and their effects on nitrogen and phosphorus use and losses.

China's pig production has increased manifold in the past 50 years, and this has greatly affected the nitrogen and phosphorus use and losses in the pig production sector. However, the magnitude of these changes are not well-known. Here, we provide an in-depth account of the changes in pig production--N and P use and total N and P losses in the whole pig production chain during the period 1960-2010--through simulation modeling and using data from national statistics and farm surveys. For the period of 2010-2030, we explored possible effects of technological and managerial measures aimed at improving the performances of pig production via scenario analysis. We used and further developed the NUtrient flows in Food chains, Environment and Resources use (NUFER) model to calculate the feed requirement and consumption, and N and P losses in different pig production systems for all the years. Between 1960 and 2010, pig production has largely shifted from the so-called backyard system to landless systems. The N use efficiencies at fattener level increased from 18 to 28%, due to the increased animal productivity. However, the N use efficiencies at the whole-system level decreased from 46 to 11% during this period, mainly due to the increase of landless pig farms, which rely on imported feed and have no land-base for manure disposal. The total N and P losses were 5289 and 829 Gg in 2010, which is 30 and 95 times higher than in 1960. In the business as usual scenario, the total N and P losses were projected to increase by 25 and 55% between 2010 and 2030, respectively. Analyses of other scenarios indicate that packages of technological and managerial measures can decrease total N and P losses by 64 and 95%, respectively. Such improvements require major transition in the pig production sector, notably, in manure management, herd management, and feeding practices.

Advances and challenges for nutrient management in china in the 21st century.

Managing agricultural nutrients to provide a safe and secure food supply while protecting the environment remains one of the great challenges for the 21st century. The fourth International Nutrient Management Symposium (INMS), held in 2011 at the University of Delaware, addressed these issues via presentations, panel sessions, and field tours focused on latest technologies and policies available to increase nutrient use efficiency. Participants from the United States, Europe, Canada, and China discussed global trends and challenges, balancing food security and the environment in countries with struggling and emerging economics, nutrient management and transport at the catchment scale, new technologies for managing fertilizer and manure nutrients, and adaptive nutrient management practices for farm to watershed scales. A particular area of interest at the fourth INMS was nutrient management progress and challenges in China over the past 40 years. China's food security challenges and rapidly growing economy have led to major advances in agricultural production systems but also created severe nutrient pollution problems. This special collection of papers from the fourth INMS gives an overview of the remarkable progress China has made in nutrient management and highlights major challenges and changes in agri-environmental policies and practices needed today. Lessons learned in China are of value to both developing and developed countries facing the common task of providing adequate food for an expanding world population, while protecting air and water quality and restoring damaged ecosystems.

An analysis of developments and challenges in nutrient management in china.

During the past 50 years, China has successfully realized food self-sufficiency for its rapidly growing population. Currently, it feeds 22% of the global population with 9% of the global area of arable land. However, these achievements were made at high external resource use and environmental costs. The challenge facing China is to further increase food production while drastically decreasing the environmental costs of food production. Here we review the major developments in nutrient management in China over the last 50 years. We briefly analyze the current organizational structure of the "advisory system" in agriculture, the developments in nutrient management for crop production, and the developments in nutrient management in animal production. We then discuss the nutrient management challenges for the next decades, considering nutrient management in the whole chain of crop production-animal production-food processing-food consumption by households. We argue that more coherent national policies and institutional structures are required for research extension education to be able to address the immense challenges ahead. Key actions include nutrient management in the whole food chain concomitant with a shift in objectives from food security only to food security, resource use efficiency, and environmental sustainability; improved animal waste management based on coupled animal production and crop production systems; and much greater emphasis on technology transfer from science to practice through education, training, demonstration, and extension services.

The driving forces for nitrogen and phosphorus flows in the food chain of china, 1980 to 2010.

Nitrogen (N) and phosphorus (P) use and losses in China's food chain have accelerated in the past three decades, driven by population growth, rapid urbanization, dietary transition, and changing nutrient management practice. There has been little detailed quantitative analysis of the relative magnitude of these driving forces throughout this period. Therefore, we analyzed changes in N and P flows and key drivers behind changes in the food (production and consumption) chain at the national scale from 1980 to 2010. Food (N and P) consumption increased by about fivefold in urban settings over this period but has decreased in rural settings since the 1990s. For urban settings, the integrated driving forces for increased food consumption were population growth, which accounted for ∼60%, and changing urban diets toward a greater emphasis on the consumption of animal products. Nutrient inputs and losses in crop and animal productions have continuously increased from 1980 to 2010, but the rates of decadal increase were greatly different. Increased total inputs and losses in crop production were primarily driven by increased crop production for food demand (68-96%) in the 1980s but were likely offset in the 2000s by improved nutrient management practices, as evidenced by decreased total inputs to and losses from cropland for harvesting per nutrient in crop. The contributions of animal production to total N and P losses to waters from the food chain increased by 34 and 60% from 1980 to 2010. These increases were caused mainly by decreased ratios of manure returned to cropland. Our study highlights a larger impact of changing nutrient management practice than population growth on elevated nutrient flows in China's food chain.

Nitrogen and phosphorus use efficiencies in dairy production in china.

Milk production has greatly increased in China recently, with significant impacts on the cycling of nitrogen (N) and phosphorus (P). However, nutrient flows within the changing dairy production system are not well quantified. The aim of this study was to increase the quantitative understanding of N and P cycling and utilization in dairy production through database development and simulation modeling. In 2010, of the entire 1987 and 346 thousand tons (Gg) of N and P input, only 188 Gg N and 31 Gg P ended up in milk. The average N and P use efficiencies were 24 and 25%, respectively, at the whole system level. Efficiencies differed significantly between the four dairy systems. Losses of N from these systems occurred via NH volatilization (33%), discharge (27%), denitrification (24%), NO leaching and runoff (16%), and NO emission (1%). Industrial feedlots use less feed per kg milk produced than traditional systems, and rely more on high-quality feed from fertilized cropland; they have very poor recycling of manure nutrients to cropland. As industrial feedlot systems are booming, overall mean N and P use efficiencies will increase at herd level but will decrease at the whole dairy production system level unless manure N and P are used more efficiently through reconnecting China's feed and dairy production sectors.

Competition between Na⁺ and Rb⁺ in the minor groove of DNA.

The competition between Na⁺ and Rb⁺ ions in the minor groove of a synthetic B-DNA dodecamer d (CGCGAATTCGCG) is studied using molecular dynamics simulations as the ratio of these two ions changing from 9:1 to 1:9 with the DNA merged into the solvent of water molecule at 298 K. When the concentration of Rb⁺ ions increases, from minority to majority, Na⁺ ions are gradually released from the A tract, and the binding sites in the minor groove are occupied by Rb⁺ ions, extending from the A tract to the whole minor groove. Comparing Na⁺ with Rb⁺ ions, the conformation of the minor groove is influenced strongly by Na⁺ ions.

Nitrogen and phosphorus use efficiencies and losses in the food chain in China at regional scales in 1980 and 2005.

Crop and animal production in China has increased significantly during the last decades, but at the cost of large increases in nitrogen (N) and phosphorus (P) losses, which contribute to ecosystem degradation and human health effects. This information is largely based on scattered field experiments, surveys and national statistics. As a consequence, there is as yet no comprehensive understanding of the changes in N and P cycling and losses at regional and national scales. Here, we present the results of an integrated assessment of the N and P use efficiencies (NUE and PUE) and N and P losses in the chain of crop and animal production, food processing and retail, and food consumption at regional scale in 1980 and 2005, using a uniform approach and databases. Our results show that the N and P costs of food production-consumption almost doubled between 1980 and 2005, but with large regional variation. The NUE and PUE of crop production decreased dramatically, while NUE and PUE in animal production increased. Interestingly, NUE and PUE of the food processing sector decreased from about 75% to 50%. Intake of N and P per capita increased, but again with large regional variation. Losses of N and P from agriculture to atmosphere and water bodies increased in most regions, especially in the east and south of the country. Highest losses were estimated for the Beijing and Tianjin metropolitan regions (North China), Pearl River Delta (South China) and Yangzi River Delta (East China). In conclusion, the changes and regional variations in NUE and PUE in the food chain of China are large and complex. Changes occurred in the whole crop and animal production, food processing and consumption chain, and were largest in the most populous areas between 1980 and 2005.