Spatiotemporal Pattern Evolution of Food and Nutrient Production in China.

Ensuring food and nutrient supply is a crucial aspect of achieving food safety. With rapid population growth, urbanization, and social and economic development, the challenges related to China's food and nutrient production have become increasingly prominent. This paper analyzed the characteristics of the spatiotemporal pattern evolution of food and nutrient production in China from 1995 to 2020, utilizing the conversion of various food nutrients and the establishment of a gravity center model. The results showed that: (1) Food production exhibited increasing trends in China, six regions, and 90% of the provinces. Notably, the structure of food production underwent significant changes in China, East China, Central-South China, Southwest China, Northwest China, and 60% of the provinces. (2) The output of all categories of food nutrients demonstrated increasing trends in China, six regions, and most provinces. At three different geographical scales, the changes of six food nutrients production structure showed significant differences. (3) Natural, political, social, economic, and technological factors played pivotal roles in influencing the gravity centers of food and nutrient production in China. The gravity centers of cereal production shifted northeast, while those of root and tuber, oil crops, and stimulants production moved westward. Additionally, the gravity centers of sugar crop, pulse, vegetable, fruit, and aquatic product production moved southwest and those of livestock and poultry production shifted northward. (4) Affected by the food production, the gravity centers of food energy, food protein, and food carbohydrate production shifted northward, while those of food fat, food vitamins, and food minerals production shifted northwest, southwest, and westward, respectively. The results of this study are of great significance for policy adjustments pertaining to the distribution pattern of food production, food security stability, and sustainable development in China.

Spatiotemporal Dynamic Evolution and Its Driving Mechanism of Carbon Emissions in Hunan Province in the Last 20 Years.

Global warming caused by carbon emissions is an environmental issue of great concern to all sectors. Dynamic monitoring of the spatiotemporal evolution of urban carbon emissions is an important link to achieve the regional "double carbon" goal. Using 14 cities (prefectures) in Hunan Province as an example, based on the data of carbon emissions generated by land use and human production and life, and on the basis of estimating the carbon emissions in Hunan Province from 2000 to 2020 using the carbon emission coefficient method, this paper uses the Exploratory Spatial-Temporal Data Analysis (ESTDA) framework to analyze the dynamic characteristics of the spatiotemporal pattern of carbon emissions in Hunan Province from 2000 to 2020 through the Local Indicators of Spatial Association (LISA) time path, spatiotemporal transition, and the standard deviation ellipse model. The driving mechanism and spatiotemporal heterogeneity of urban carbon emissions were studied by using the geographically and temporally weighted regression model (GTWR). The results showed that: (1) In the last 20 years, the urban carbon emissions of Hunan Province have had a significant positive spatial correlation, and the spatial convergence shows a trend of first increasing and then decreasing. Therefore, priority should be given to this relevance when formulating carbon emission reduction policies in the future. (2) The center of carbon emission has been distributed between 112°15'57″~112°25'43″ E and 27°43'13″~27°49'21″ N, and the center of gravity has shifted to the southwest. The spatial distribution has changed from the "northwest-southeast" pattern to the "north-south" pattern. Cities in western and southern Hunan are the key areas of carbon emission reduction in the future. (3) Based on LISA analysis results, urban carbon emissions of Hunan from 2000 to 2020 have a strong path dependence in spatial distribution, the local spatial structure has strong stability and integration, and the carbon emissions of each city are affected by the neighborhood space. It is necessary to give full play to the synergistic emission reduction effect among regions and avoid the closure of inter-city emission reduction policies. (4) Economic development level and ecological environment have negative impacts on carbon emissions, and the population, industrial structure, technological progress, per capita energy consumption, and land use have a positive impact on carbon emissions. The regression coefficients are heterogeneous in time and space. The actual situation of each region should be fully considered to formulate differentiated emission reduction policies. The research results can provide reference for the green and low-carbon sustainable development of Hunan Province and the formulation of differentiated emission reduction policies, and provide reference for other similar cities in central China.

[Spatiotemporal Dynamic Evolution and Gravity Center Migration of Carbon Emissions in the Main Urban Area of Chongqing over the Past 20 Years].

Global warming caused by carbon emissions is an environmental issue that is of great concern to all walks of life. Dynamic monitoring of the spatiotemporal evolution of urban carbon emissions is an important part of achieving the regional double-carbon goals. Taking the main urban area of Chongqing as an example, based on the data of land use and energy consumption, this study estimated the carbon emissions of 153 townships and streets in the main urban area of Chongqing from 2000 to 2020 by using the carbon emission coefficient method. Additionally, using the ESTDA framework to pass the LISA time path, spatiotemporal transition, and the standard deviation ellipse model from the perspective of spatiotemporal interaction, the spatiotemporal dynamic evolution of carbon emissions in the main urban area and the shift in the center of gravity over the past 20 years were analyzed. The results showed that: ① in the past 20 years, the carbon emissions in the main urban and rural areas have had a significant positive spatial correlation, and the spatial convergence showed a trend of first decreasing and then increasing. ② In the past 20 years, there were 126 township streets with low and medium relative lengths (accounting for 82%), indicating that the local spatial structure of township carbon emissions in the main urban area had strong stability; the total number of township streets with low and medium curvatures was 138 (accounting for 90%), indicating that the volatility of the main urban and rural carbon emissions in the direction of spatial dependence was relatively stable; there were 113 township streets (accounting for 74%) of the synergistic growth type, indicating that the main urban and rural carbon emissions were relatively stable. The emission pattern had strong spatial integration. ③ In the past 20 years, the spatiotemporal agglomeration index was greater than 70%, indicating that the local spatial correlation pattern and agglomeration characteristics of carbon emissions in the main urban and rural areas had strong stability. 4 In the past 20 years, the center of carbon emission in the main urban area had been distributed between 106°30'43″-106°32'42″E, 29°33'34″-29°35'56″N, and the center of gravity shifted to the northeast as a whole. The spatial distribution changed from the "northwest-southeast" pattern to the "northeast-southwest" pattern. These results can provide reference for the green and low-carbon sustainable development of Chongqing and the formulation of differentiated emission reduction policies, as well as provide reference for other similar mountain cities in western China.

A study on the evolution of economic patterns and urban network system in Guangdong-Hong Kong-Macao greater bay area.

The COVID-19 pandemic has seriously affected China's macroeconomy, industrial transformation, and high-quality development. Research on economic patterns and urban network systems can provide a reference for healthy development of the regional economic system. The evolution of the economic pattern and urban network system of Guangdong-Hong Kong-Macao Greater Bay Area (GBA) from 2010 to 2020 is investigated using methods (e.g., the gravity center model, the gravitational force model, social network analysis, and geographic information system). (1) The gravity center of gross domestic product (GDP) of the GBA is located in Nansha district, Guangzhou, with a skewing direction northwest-east-northwest and a movement rate of "large-small-large." The center of import and export and the center of consumption show a "zigzagging migration" in which the center of investment shows an "irregular (random) migration". (2) The economic connection degree of cities in the GBA exhibits a high ascending velocity, and the whole area tends to be mature, with a significant effect of spatial proximity. With the steady increase in network density, there is significant polarization of network centrality in the region. The four major cohesive subgroups have been relatively stable and consistent with the degree of geographic proximity of the cities. The center-periphery structure is more significant, in which the core area is extended to the cities on the east coast of the Pearl River Estuary, thus forming the core cluster of "Hong Kong-Shenzhen-Guangzhou-Dongguan." In this study, the evolution of economic patterns and urban network systems in the GBA over the past decade is analyzed using multiple methods (i.e., gravity model, urban network system analysis, and geographic information system) based on urban socioeconomic data by starting from various spatial elements (e.g., "points, lines, and networks") to gain insights into and optimize research on regional economic development after the COVID-19 pandemic.

Spatio-Temporal Variation and Influencing Factors of the Coupling Coordination Degree of Production-Living-Ecological Space in China.

Territorial space is a multi-functional complex. The coordinated production-living-ecological space (PLES) effectively coordinates the man-land relationship, promotes regional sustainable development, and maximizes territorial space. How to build a high-quality national spatial layout and support system for development has become a hot topic of concern in all sectors of society. However, few studies have explored the coupling coordination considering the various production-living-ecological functions of land use type and its influencing factors of PLES at the county scale in China. To address the gap, based on the connotation of PLES theory, this study established a classification and evaluation system for PLES and analyzed the spatio-temporal characteristics, coupling coordination degree, spatial autocorrelation, and influencing factors of PLES in China from 2000 to 2020. The results are as follows: (1) The production space index and living space index in China showed a continuous increase tendency, while the ecological space index decreased continuously during the study period. The production space and living space were concentrated in the east of Hu Line, and the ecological space indexes in mountainous areas were significantly higher than those in plain areas during the study period. (2) The gravity centers of PLES all migrated to the west of China to different degrees during the study period. (3) From 2000 to 2020, the basically balanced category was the main coupling coordination type, and the number of seriously unbalanced categories accounted for the least. In the west of the Hu Line, the seriously unbalanced category was dominant, while in the east of the Hu Line were the moderately unbalanced categories and above. (4) During the study period, the low-low type was the main relationship type, widely distributed in western China, followed by the high-high type, mainly situated in the North China Plain, Yangtze River Delta, Pearl River Delta, Jianghan Plain, Chengdu Plain, Northeast China Plain, and some provincial capital cities. (5) Regression results showed that natural factors were the main reason restricting the coordinated development of PLES, and socioeconomic factors could effectively promote the coordinated development of PLES. Landscape pattern also significantly influenced the coordinated development of PLES, but varied greatly. The findings of this study can provide a scientific reference for the optimization of territorial space layout and the promotion of high-quality development of territorial space.

Gravity center estimation for evaluation of standing whole body compensation using virtual barycentremetry based on biplanar slot-scanning stereoradiography - validation by simultaneous force plate measurement.

BACKGROUND: Whole body standing alignment (WBSA) in terms of biomechanics can be evaluated accurately only by referring the gravity line (GL) which lies on the gravity center (GC). Here, we introduce a method for estimating GL and simultaneous WBSA measurement using the EOS® imaging system and report on the reproducibility and reliability of the method. METHODS: A 3-dimensional (3D) avatar to estimate GC was created following three steps: 3D reconstruction of the bone based on EOS images; deformation into a generic morphotype (MakeHuman statistical model) before density integration with 3D rasterization of the full body into 1-mm3 voxels (the content of each voxel is considered homogeneous); computation of the density of all the voxels provides the center of mass, which can be projected onto the floor as the GC of the full body, providing the GL in relation to the WBSA. The repeatability, reproducibility, and accuracy of the estimated GC and body weight of the avatar were compared with clinical estimation using a force plate in healthy volunteers and patients with degenerative and deformative diseases. RESULTS: Statistical analyses of the data revealed that the repeatability and reproducibility of the estimation was high with intra-rater and inter-rater intraclass correlation coefficient. ≥0.999. The coordinate values of the GC and body weight estimation did not differ significantly between the avatar and force plate measurements, demonstrating the high accuracy of the method. CONCLUSION: This new method of estimating GC and WBSA is reliable and accurate. Application of this method could allow clinicians to quickly and qualitatively evaluate WBSA with GL with various spinal malalignment pathologies.

Addressing the Location Problem of a Perishables Redistribution Center in the Middle of Europe.

This work aims to contribute to the debate on practical utilization of different location models for consolidation, redistribution, and repackaging centers in a supply chain to optimize shipments, thereby reducing food loss and waste, within the framework of quality of customer service improvement. The scenario in question is the creation of a redistribution center for highly perishable products (fruits and vegetables) from southeast Spain-the leading European supplier-for customers throughout Europe. It is estimated that 10% of exports (more than 530,000 metric tons) from this area are returned by customers due to minor defects. These products cannot be reused and are therefore wasted. Regarding the methodology, comparisons were made between the p-median, gravity p-median, and p-center models. Scenarios of change in demand and randomness in distances were also tested. In addition, the modelling used included the cost and time within a multicriteria optimization framework to assess the possibility of a transport mode change. It was observed, for example, that the gravity p-median model proved useful for perishable products and the logistics strategy chosen. Furthermore, the p-median model displayed strong robustness against long-term changes in demand and random distances. In general, it was demonstrated that this strategy would successfully reduce the response time and distance of shipment from the distribution center to the customers and thereby improve sustainability of the service, reducing the waste related to direct shipments. Furthermore, this research also demonstrated the difficulty of using intermodality in this context, mainly due to transit time, which would undoubtedly increase the waste generated.

Determining the contributions of climate change and human activities to the vegetation NPP dynamics in the Qinghai-Tibet Plateau, China, from 2000 to 2015.

Reflecting on the change in the global biodiversity pattern, the Tibetan Plateau, considered to be a "natural laboratory" for analyzing environmental change in China and around the world, has suffered profound changes in the vegetation ecosystem. This study introduces the gravity center model and geographical detectors to examine and discuss the spatial-temporal change pattern and the driving mechanism behind vegetation net primary production (NPP) in the Qinghai-Tibet Plateau from the year 2000 to 2015 while also quantitatively classifying the relative roles incorporated in the NPP change process. The study found that (1) from 2000 to 2015, the annual average NPP of the Tibetan Plateau demonstrated a declining trend from southeast to northwest. (2) The gravity center of vegetation NPP on the Qinghai-Tibet Plateau seems to have shifted eastward in the past 16 years, indicating that the level of vegetation NPP in the east depicts a greater increment and growth rate than the west. (3) In the arid regions, temperature and rainfall appear as the dominant factors for vegetation NPP, while slope and aspect parameters have constantly assumed dominancy for the same in the tropical rainforest-monsoon ecological zone in southeastern Tibet. (4) The structure of vegetation NPP exhibits an interaction between human and natural factors, which enhances the influence of single factors. (5) Considering the global ecological change and related human activities, certain differences are observed in the dominant and interaction factors for different study periods and ecological subregions in the Qinghai-Tibet Plateau. The research results could prove conclusive for vegetation ecological protection in the Qinghai-Tibet plateau.

A rapid performance evaluation approach for lower mobility hybrid robot based on gravity-center position.

This article develops a rapid performance evaluation approach for lower mobility hybrid robot, which provides guidance for manipulator evaluation, design, and optimization. First, a general position vector model of gravity center for the lower mobility hybrid robot in the whole workspace is constructed based on a general inverse kinematic model. A performance evaluation index based on gravity-center position is then proposed, where the coordinates pointing to the supporting direction are selected as the evaluation index of the robot performance. Furthermore, the credibility of the evaluation approach is verified from a 5-DOF hybrid robot (TriMule) by comparing with the condition number and the first natural frequency. Analysis results demonstrate that the evaluation index can not only reflect the performance spatial distribution in the whole workspace but also is sensitive to the performance difference caused by mass distribution. The proposed performance evaluation approach provides a new index for the rapid design and optimization of the cantilever robot.

Spatiotemporal disequilibrium and spillover effect of fine particulate matter across China.

Massive monitoring data requires effective statistical analysis methods. This paper aims to visualize the spatiotemporal characteristics and spillover effect of air pollutants. Ground-based PM2.5 data in 336 cities across China revealed a tough but improving situation. The PM2.5 average annual concentrations in 2016 and 2017 were 47 ± 18 µg/m3 and 44 ± 16 µg/m3 respectively, but a worse, or at least a not-improving PM2.5 situation happened in winter. A slight declining north-south disequilibrium and a growing east-west disequilibrium exhibited in 2017, along with an increasing weight of eastern and southern pollution in the proportion of the overall pollution level. North-south disequilibrium existed stably throughout the year but east-west disequilibrium was erratic. Nearly half of the cities exhibited significant spillover effects, presenting 2 clusters with spillover by high concentrations and 3 clusters with spillover by low concentrations. Most cities in Hebei, Shandong and Henan provinces showed a high but decreasing spillover effect, but increasing trend happened in the cities in Anhui and Shanxi provinces. A significant correlation appeared between the city population and PM2.5 concentration. Population density explained about 25% of the PM2.5 concentration change, and the explanation ability increased in 2017. A higher influence of population on PM2.5 concentration happened in the early stage of city development, and the influence exhibited spatial differences. The city population and PM2.5 spillover effect existed an overall positive correlation, but the population only addressed about 10% of the spillover effect change. Our findings provide important information for the joint prevention and control of air pollution in China, and the approach proposed in this paper is applicable to other fields.

Diagnosing cropland's allowable range and spatial allocation in China's typical mountainous plateau area: An evaluation framework based on ecological carrying capacity.

Natural capital serves as a major constraint that affects the sustainable development of mountainous plateau areas. Determining ecological carrying capacity (ECC), as the key to measuring the critical natural capital of cropland, is needed for sustainable development. This study aims to provide new insights into ECC by diagnosing whether human activities are within the allowable range of natural capital and whether the spatial allocation of natural capital is reasonable in such specific areas. Taking Yunnan Province, China as the study area, we proposed an improved Ecological Footprint (EF) model to evaluate cropland's ecological capacity (CEC), and then, a framework of balance evaluation and spatial optimal allocation was constructed to examine the cropland's allowable range and optimize its spatial allocation if found unreasonable. Results show the following. (1) The per capita CEC of Yunnan Province between 2009 and 2016 decreased from 0.103 ha/capita to 0.095 ha/capita, and the cropland ecological balance index (EBI) presented a "critical overload" state ranging from 0.433 to 0.463, at which the supply exceeded the demand. Hence, the cropland was not within the allowable range in terms of supply-demand balance. (2) The comprehensive Gini coefficient of CEC was 0.462-0.515, and the gravity center of CEC deviated from the geometric center and shifted toward the westward, thereby, CEC is neither balanced in terms of spatial allocation nor coordinated with the population, economy, and resource environment. (3) The spatial allocation pattern of the study area was grouped into five zones on the basis of the optimization model. These zones are key optimization zone, adjustment optimization zone, maintenance zone, reasonable reduction zone, and key reduction zone. Accordingly, the targeted and differentiated strategies were accordingly put forward. Our study can contribute to identifying the practical approach to sustainable ecosystem management in mountainous plateau areas from the perspective of ECC and are beneficial for decision-making as regards new policies on cropland protection and Chinese ecological civilization construction.

The effect of sleep disturbance in patients with chronic dizziness.

CONCLUSIONS: The comorbidity of sleep disturbance with chronic dizziness in women was related to the intensity of distress and interference with their lives due to dizziness, although it was not related to objective variables of dizziness. In addition, the presence of sleep disturbance was associated with severe anxiety and depression, and low health-related quality-of-life (QoL). OBJECTIVES: This study investigated the effect of sleep disturbance in patients with chronic dizziness on symptoms of dizziness, handicaps due to dizziness, health-related QoL, and emotional distress. METHOD: The participants of this study were 252 in-patients with chronic dizziness. Participants completed questionnaires containing the Dizziness Handicap Inventory (DHI, three sub-scales: Physical [DHI-P], Emotional [DHI-E], and Functional [DHI-F] scores), Pittsburgh sleep quality index (PSQI-J), Hospital Anxiety and Depression Scale (HADS), and Medical Outcomes Study 8-items Short Form Health Survey (SF-8, health-related QoL). The participants then underwent gravity center fluctuation measurement as an objective indicator of the severity of dizziness. RESULTS: The prevalence of sleep disturbance (PSQI-J global score ≧6) was 65.1% in these participants. Two-way ANOVA of the DHI scores showed significant interaction between sleep disturbance and sex in DHI total, DHI-E score, and DHI-F score, indicating that these scores were higher in women with sleep disturbance. Regarding DHI-P score, only the main effect of sex was significant (women > men). Sleep disturbance had no significant effect on objective indicators of severity of dizziness. Patients with sleep disturbance had significantly higher HADS scored and a lower SF-8 scored than patients without sleep disturbance.

[Ecological risk assessment of Taihu Lake basin based on landscape pattern]. / åŸºäºŽæ™¯è§‚æ ¼å±€çš„å¤ªæ¹–æµåŸŸç”Ÿæ€é£Žé™©è¯„ä¼°.

Taihu Lake basin was selected as the study site. Based on the landscape data of 2000, 2005, 2010 and 2015, the Markov and CLUE-S models were used to simulate the landscape types with different scenarios in 2030, and landscape ecological risk index was constructed. The shift of gravity center and spatial statistics were used to reveal landscape ecological risk of Taihu Lake basin with temporal and spatial characteristics. The results showed that the ecological risk mainly was at medium and low levels in Taihu Lake basin, and the higher ecological risk areas were mainly distributed at the Taihu Lake area during 2000 to 2015, and the low ecological risk was transferred from the southwest and south of Taihu Lake to the developed areas in the northern part of Taihu Lake area. Spatial analysis showed that landscape ecological risk had negative correlation with natural factors, which was weakened gradually, while the correlation with socioeconomic factors trended to become stronger, with human disturbance affecting the landscape ecological risk significantly. The impact of socioeconomic factors on landscape ecological risks differed in different urbanization stages. In the developing area, with the economic development, the landscape was increasingly fragmented and the ecological risk was correspondingly increased. While in the developed area, with the further development of the economy, the aggregation index was increased, and fragmentation and separation indexes were decreased, ecological construction was restored, and the landscape ecological risk began to decline. CLUE-S model simulation showed that the ecological risk of Taihu Lake basin would be reduced in future, mainly on the low and relatively low levels. Taihu Lake area, both in history and the future, is a high ecological risk zone, and its management and protection should be strengthened.

The Spatial-Temporal Characteristics of Air Pollution in China from 2001-2014.

To provide some useful information about the control of air pollution in China, we studied the spatial-temporal characteristics of air pollution in China from 2001-2014. First, we drew several line charts and histograms of the Air Pollution Index (API) and Air Quality Index (AQI) of 31 capital cities and municipalities to research the distribution across different times and cities; then, we researched the spatial clustering of API and AQI; finally, we examined the shift of the gravity center of API and AQI in different years and months. The API values had a decreasing trend: the high values had a clustering trend in some northern cities, and the low values had a clustering trend in some southern cities. The AQI values were relatively low, from 15:00-17:00 during the day. The gravity center of API had a trend of moving south from 2001-2003, then fluctuated in an unordered pattern and moved north in the winter. The AQI gravity center did not have a regular shift during different months. In conclusion, the government should take action to mitigate air pollution in some typical cities, as well as air pollution during the winter.

Gastric emptying and duodenal motility upon intake of a liquid meal with monosodium glutamate in healthy subjects.

Glutamate is thought to serve as a special signal for gut functions. We investigated the effects of monosodium l-glutamate (MSG) on gastric emptying and duodenal motility. Ten healthy male volunteers underwent rapid magnetic resonance imaging (MRI) of the abdomen. Coronal images were successively acquired after ingestion of liquid meal (200 kcal in 200 mL: 9 g protein, 28.4 g carbohydrate, 5.6 g fat, 370 mg Na(+)) with and without 0.5% MSG. During the acquisition of MRI, participants breathed freely. In all participants, the gastric residual volume gradually decreased to 80.1 ± 14.2% without MSG and to 75.9 ± 14.3% with MSG after 60 min (P = 0.45 between the groups, n = 10). In two of 10 participants, gastric emptying slowed down significantly, whereas in the remaining eight participants, gastric residual volume decreased to 84.0 ± 13.1% without MSG, and to 73.0 ± 14.6% with MSG after 60 min (P = 0.015, n = 8). There was no difference in the shape of the stomach between groups. In four of the eight participants responding positively to MSG, the duodenum wall was sufficiently identified to quantify the motions. The inclusion of MSG enhanced duodenal motility, judging from changes in (1) the magnitude of the duodenal area, (2) the center of gravity, and (3) the mean velocity of the wall motions. The third parameter most significantly indicated the excitatory effect of l-glutamate on duodenum motility (~ three- to sevenfold increase during 60 min, P < 0.05, n = 4). These results suggest that MSG accelerates gastric emptying by facilitating duodenal motility, at least in subjects with positive responses to MSG.

Variabilidad espacial y temporal de larvas de jurel Trachurus murphyi en el Perú entre 1966 - 2010

El análisis espacial y temporal de larvas de jurel Trachurus murphyi en el mar peruano entre los años 1966 y 2010 confirma su presencia constante durante todo el periodo estudiado. En general, en este periodo la abundancia de larvas de jurel T. murphyi muestra una tendencia ligeramente ascendente destacándose cambios en la distribución espacial y una alta variabilidad interanual, con cortos periodos de alta abundancia promedio, intercalados con periodos más prolongados y de baja abundancia. El promedio anual estimado varió entre 3 y 79 larvas/m². La distribución espacial presentó tres periodos importantes: uno con mayores densidades de larvas al sur de los 14°S, entre 1970 y 1979; cambió hacia el norte de esta latitud, entre 1980 y 1999; y otro de mayor densidad al sur de los 18°S, en el último periodo 2000 - 2010. Los centros de gravedad de la distribución de larvas presentaron tres periodos muy notorios: fueron más costeros hacia el sur de los 14°S, entre 1966 y1978; más oceánicos y al norte de los 14°S, entre 1979 y 1994; y con una posición intermedia entre 1995 - 2010. Se discute la relación entre la distribución de las larvas con las variables oceanográficas y la distribución de T. murphyi adultos y juveniles, además se destaca que el mar del Perú es un centro principal y permanente de actividad reproductiva de esta especie.

Constant presence of Jack mackerel Trachurus murphyi larvae in the Peruvian sea between 1966 and 2010 was confirmed by an analysis of their spatial and temporal variability. In general, there is a slight positive trend in abundance of Jack mackerel T. murphyi larvae, with noticeable changes in their spatial distribution and high interannual variability. High abundance of larvae is observed in some years, which are usually followed by a longer sequence of poor abundance years. Yearly averages varied between 3 and 79 larvae/m². The spatial distribution of average larvae density showed three notorious periods along time: the first between 1970 and 1979 with higher larvae densities south of 14°S; the second between 1980 and 1999 with the higher densities to the north of 14°S; and the third between 2000 and 2010 with higher densities south of 18°S. The displacement of the centers of gravity of the spatial distribution marked three noticeable periods: between 1966 and 1978 were more coastal, south of 14°S; between 1979 and 1994 more oceanic and north of 14°S; and between 1995 and 2010 which were at an intermediate position. The relationship of larvae density with oceanographic variables as well as with the distribution of adult and juvenile Jack mackerel T. murphyi are discussed, stressing the observation that there is a main center of permanent spawning activity of this species in Peruvian waters.