A | Mosquitoes use the body odor, heat, and carbon dioxide that humans emit, varying from person to person, to find their next meal. The study, which was published in the scientific journal Cell, reveals that mosquitoes may perceive odors via a variety of distinct pathways, in contrast to animals, which have a single set of neurons that detect each sort of odor.,Female mosquitoes use the variety of odors that people and other animals produce to find the blood that will feed their eggs. The olfactory neurons in the insects' antennae, which are where they take up scents, detect and send scent information to the brain.,Groups of human-odor receptors on the olfactory neurons in the antennae of female mosquitoes (Aedes aegypti) were rendered inactive by the study's lead author Meg Younger and her colleagues at Boston University in Massachusetts using the gene editing tool CRISPR.,"We found that there’s a real difference in the way mosquitoes encode the odors that they encounter compared to what we’ve learned from other animals,” Younger is quoted as saying in the Guardian report on the findings.,According to Younger, the scientists believed that mosquitoes would adhere to the core tenet of olfaction, which states that each neuron expresses only one type of receptor.,“Instead, what we’ve seen is that different receptors can respond to different odors in the same neuron," she added.,This reportedly suggests that mosquitoes can still detect human odors after losing one or more receptors. The researchers asserted that this backup system may have developed as a survival mechanism.,"The mosquito Aedes aegypti is specialized to bite humans, and it is believed that they evolved to do that because humans are always close to fresh water and mosquitoes lay their eggs in fresh water. We are basically the perfect meal, so the drive to find humans is extremely strong," Younger explained,In the end, the researchers argued, knowing how the mosquito brain perceives human odor could be used to influence biting behavior and stop the spread of diseases like malaria, dengue fever, and yellow fever that are transmitted by those insects.,"One major strategy for controlling mosquitoes is to attract them to traps to remove them from the biting population. If we could use this knowledge to understand how human odor is represented in the mosquito antennae and brain, we could develop blends that are more attractive to mosquitoes than we are. We could also develop repellants that target those receptors and neurons that detect human odor," Younger concluded.,Notably, Christopher Potter at Johns Hopkins School of Medicine in Maryland recently found a similar phenomenon in fruit flies, or Drosophila melanogaster.,“If one of these types of olfactory receptors is mutated or no longer functioning, there’s this backup system," Potter is quoted as saying in the New Scientist report. “It’s changing the dogma of what we thought we knew about the olfactory system.”,Science & TechSmell of Blood: Mosquitoes' Scent-Based Host-Seeking Mechanism Revealed16 May, 05:54 GMT。 正值暑期旅游旺季，北京首都机场T3航站楼内办理离境退税的游客络绎不绝。记者昨天从北京海关获悉，今年7月1日起，离境退税“小额抽检”及全流程无纸化新政实施，新政落地首月，首都机场海关共验核退税申请单13430票，申请退税商品总金额1.17亿元，对应退税金额1453万元，入境消费热度持续攀升。
B | 首都机场内，一位首次来华旅游的意大利女士正在离境退税自助机前进行操作。记者看到，她购入了一些衣服和护肤品，完成身份核验后，系统快速处理单据信息并生成了完整的退税明细，确认金额并选定退税渠道后，本次退税操作便已完成。“中国的护肤品在意大利很有名，中国的文化和城市景象也让我深受震撼，体验感特别好。
C | 随后，一位来自俄罗斯的计算机教师因课程录制需要购入了几个大疆无线麦克风，也前来申报退税，“预计能退200多元。”他感叹道，“验核手续很方便，我打算后续再购入一批。” 这一个个便利体验，都得益于自今年7月1日起全面推行的离境退税新政。其中，“全流程无纸化”让整个验核流程更加便捷快速，旅客业务办理时间进一步缩减。 北京海关所属首都机场海关旅检一处副处长梁姝说，新政落地后，所有单据实现电子化，海关通过扫描旅客专属服务码，就能从系统中一键调取完整的电子退税单、电子发票，线上即可完成海关在线核验。 而“小额抽检制”则兼顾了办税效率与监管规范。据了解，北京海关对退税销售额1万元以下的退税申请单，实行按比例随机抽检模式，不再逐单开展实物验核；退税销售额1万元及以上的申请单，仍严格执行逐单实物验核标准。
D | 北京海关相关负责人介绍，从系统显示的退税商品种类看，境外旅客的“购物车”呈现出鲜明特点，除传统的箱包、服装外，国产科技品牌电子产品如手机、耳机等也备受追捧，成为退税商品中的热门品类。同时，具有中国文化特色的纪念品、潮流盲盒等也获得不少外国游客的青睐。
E | 据了解，在首都机场T3航站楼，每天的上午时段是离境退税的高峰期。今年以来，退税申请单数量大幅增长。数据显示，7月首都机场海关共验核退税申请单13430票，同比增长近2.7倍；申请退税商品总金额1.17亿元，对应退税金额1453万元，同比增幅均超15%。（记者 鹿杨）。
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