基于迁移学习与YOLOv8n的田间油茶果分类识别

为降低视觉引导式油茶果采摘机器人采摘被遮挡油茶果时造成的果树和抓取装置损伤,该研究提出了一种基于迁移学习和YOLOv8n算法的油茶果分类识别方法,将油茶果分成无遮挡和遮挡两类。首先,采用COCO128目标检测数据集作为源域,苹果数据集为辅助域的迁移学习方法训练模型。其次,将学习方法、训练数据量、学习率和训练轮数这4种因素组合,共进行了52组YOLOv8n检测性能的消融试验。最后,将YOLOv8n模型与YOLOv3-tiny、YOLOv5n和YOLOv7-tiny等模型进行比较。试验结果表明,随机权重初始化方式受训练数据量和学习率影响较大,学习率为0.01时模型检测效果最好;而迁移学习方法仅用随机权重初始化1/2的数据量即可达到与其相当的平均精度均值;迁移学习方式下,YOLOv8n模型的平均精度均值最高达到92.7%,比随机权重初始化方式提升1.4个百分点。与YOLOv3-tiny、YOLOv5n和YOLOv7-tiny等模型相比,YOLOv8n模型的平均精度均值分别提高24.0、1.7和0.4个百分点,研究结果可为YOLOv8n模型训练参数优化和油茶果分类识别提供参考。     

Effect of quinoa flour on gluten-free bread batter rheology and bread quality

A new gluten-free bread formulations composed of quinoa, buckwheat, rice flour and potato starch were developed in the present study. Rheological characteristics of the bread batter with increasing amount of quinoa were determined; storage (G′) and loss modulus (G″) values were also measured for investigation of viscoelastic properties. To evaluate the quality of breads; technological and physical (bake loss %, specific volume, texture, microstructure, color), chemical (protein, moisture, ash) and sensory properties were determined. All batter formulations independent of the quinoa amount exhibited pseudoplastic behavior, and G′ values were found to be higher than G″ values in expressing the solid like characteristics of the batter. Amount of quinoa flour addition did not present significant difference on bake loss%, specific volume and protein content (p>0.05); however, 25% quinoa flour bread displayed better results with its higher sensory scores and softer texture. Quinoa and buckwheat flour mixture therefore will be a good alternative for conventional gluten-free bread formulations.     

Commercial agriculture as creative destruction or destructive creation: a case study of chili cultivation and plant‐pest disease in the southern Yucatán region

Agricultural change encompasses both social and ecological alterations, some negative, some positive. Studies of land change and land degradation treat plant pest and diseases triggered by agricultural change in an inconsistent fashion. A study of the southern Yucatán region of Mexico reveals that the shift to commercial chili cultivation yields both positive and negative consequences, akin to the concepts of creative destruction and destructive creation. The negative consequences are dramatically amplified by persistent plant pest and diseases apparently triggered by the means of cultivation and by the inclusion of the region into a national marketing structure. Thus, while providing economic benefits to some of the farmers of the region the short‐ and long‐term impacts of chili cultivation on farmer households is mixed. Studies of agricultural land‐use change and household economics will benefit by incorporating plant pests and diseases as one of the suite of factors involved in land degradation. Copyright © 2004 John Wiley & Sons, Ltd.     

2n花粉静电分选的机理研究

在静电分选海棠花粉的实验基础上,从花粉细胞膜电位和花粉在电场中荷电的角度出发,作了花粉在静电场中的受力及运动分析,研究了２ｎ花粉的分选机理,从而得出了２ｎ花粉在极板上的位置比ｎ花粉位置要靠下的结论。     

裙带菜幼孢子体营养细胞多倍体育种

本文报道了裙带菜幼孢子体的营养细胞2n配子体的产生过程及其发育特点、性分化、发育成熟时间,进行了2n配子体间及与正常配子体的杂交,培育出3n、4n幼孢子体。测定了不同倍性幼孢子体的生长。观察到3n幼孢子体的染色体数为90。     

鱿鱼鱼精蛋白的提取_纯化及其生化特性

鱼精蛋白（Ｐｒｏｔａｍｉｎｅ）是一种常与ＤＮＡ结合,存在于鱼类成熟精巢中的碱性蛋白。由于其生化组成的特点,鱼精蛋白不仅具有促使细胞发育繁殖的作用,而且一旦将其分离出来,能有效抑制多种食品腐败菌的生长和繁殖［Ｍｉｌｅｒ１９４２］。同时,这种鱼精蛋白还有...     

记蜂透翅蛾属一新种(鳞翅目:透翅蛾科)

新种－庐山蜂透翅蛾Ｓｐｈｅｃｏｓｉｅｓｉａｌｕｓｈａｎｅｎｓｉｓ,ＸｕｅｔＬｉｕ,ｎ．ｓｐ．近似荔 蜂透翅蛾Ｓ．ｌｉｔｃｈｉｖｏｒａＹａｎｇｅｔＷａｎｇ和吕宋蜂透翅蛾蛾Ｓ．ｍｅｌａｎｏｓｔｏｍａＤｉａｋｏｎｏｆｆ但其虫体几乎完全蓝黑色,腹其窄却不呈柄状,后跗节很长,雄性外生殖器的抱器片后端有一小乳突,因而很易区分。     

魔芋不同类型愈伤组织及分化能力研究

以花魔芋球茎和白魔芋幼嫩叶柄为外植体诱导愈伤组织,经过3次或3次以上继代培养,魔芋愈伤组织可形成3种不同类型：A型水渍状,半透明;B型—浅黄色,表面呈球形瘤状突起;C型—绿色或橙红色,结构致密。3种类型的愈伤组织在不同的培养条件下可以相互转变,不同类型的愈伤组织分化能力不同。组织学切片显示了3种类型愈伤组织的细胞类型和组织结构特征。     

Impact of sublethal di‐n‐butyl phthalate on the aquaculture fish species Nile tilapia (Oreochromis niloticus): histopathology and oxidative stress assessment

Phthalates such as di‐n‐butyl phthalate (DBP) and their esters are widely used plasticizers, their ubiquitous presence in daily life, inevitably leads to their restricted use due to important environmental pollution and health impacts and endocrine disruption potential. The aim of this study was to examine the effects of a sublethal concentration of 10 mg L^?1 DBP on haematocrit (HCT) values, gills and liver histology, malondialdehyde (MDA, 2‐thiobarbituric acid‐TBA reactivity) and reduced glutathione (GSH) levels in gills and liver tissue as oxidative stress biomarkers in the aquaculture fish species Nile tilapia (Oreochromis niloticus) after 24 (DBP‐24) and 96 (DBP‐96) h exposure. No differences were found between per cent HCT values in the 24 h exposure groups (P > 0.05). Response of antioxidant defence systems in liver and gill tissues of the fish were dependent on exposure duration and changed to a higher extent during 96 h. MDA levels in liver tissue increased in DBP treated fish in comparison to the control fish. However, the differences between the exposure and control groups were not significant (P > 0.05). A statistically significant decrease (P > 0.05) was recorded in gill MDA levels in the DBP‐96 group when compared to the control and DBP‐24 groups. The liver GSH levels were unchanged in the DBP treated fish. However, GSH levels were significantly lower in the gill tissue of the DBP‐96 group. Exposure to DBP caused several degenerative changes in the histology of gill and liver tissue. Gills displayed hyperaemia, epithelial lifting, oedema, talengiectasia, epithelial hyperplasia and fusion of secondary lamellae, whereas in liver several circulatory anomalies (hyperaemia, blood congestion and sinosoid dilatation) and vacuolization of hepatocytes were observed. Histopathological results demonstrated that the gills were more affected than the liver perhaps due to their direct contact with DBP.