Analysis of Freemium Business Model Considering Network Externalities and Consumer Uncertainty

An emerging business model increasingly used by companies in the online software market is to provide both a free basic version and a paid premium version for a service or a product to customers. Such a setting is often called freemium model. The existence of the free version can reduce the customer uncertainty regarding the evaluation of the commercial software and make use of network effect to improve the firm’s profit. However, the freemium model may also have the cannibalization effect which can hurt the profit. Hence, the firm needs to determine the optimal content for the free version and the optimal price for the premium version to maximize its profit. In this paper, first, we obtain the optimal decisions of the freemium model and their properties. Second, we compare the freemium model with the traditional charge-for-everything model that all content of the product need to be charged in terms of the profit, customer welfare, and social welfare. The results show that when customer underestimates the value of the software significantly and the true value of the software is high enough, the freemium model can generate higher profit, higher customer welfare, and higher social welfare. Otherwise, the freemium model may not deliver the desired results.     

Transformer-Based Deep Learning Network for Tooth Segmentation on Panoramic Radiographs

Panoramic radiographs can assist dentist to quickly evaluate patients’ overall oral health status. The accurate detection and localization of tooth tissue on panoramic radiographs is the first step to identify pathology, and also plays a key role in an automatic diagnosis system. However,the evaluation of panoramic radiographs depends on the clinical experience and knowledge of dentist,while the interpretation of panoramic radiographs might lead misdiagnosis. Therefore, it is of great significan...     

滁菊再生体系建立及褪黑素对不定根诱导和抗旱性的影响

以所选育的滁菊优质高产脱毒株系的野外当年生茎段为外植体,建立高效的滁菊离体再生体系,探究褪黑素对滁菊不定根诱导的影响,在此基础上对褪黑素提高滁菊抗旱性进行初步探索.结果表明:用0.1％的HgCl2溶液消毒3 min时茎段的成活率高达93.3％;添加有0.5 mg·L-16-BA的MS培养基可促使无菌茎段直接诱导出不定芽,诱导率为100％,平均每个外植体产生4.67个不定芽,继代培养后不定芽的增殖系数为7.76;添加有0.2 mg·L-1 GA3的MS培养基最有利于不定芽的伸长,平均高度为4.16 cm;将伸长的芽接种在添加0.1 mg·L-1 IBA的1/2 MS培养基中最有助于不定根的诱导,不定根的诱导率为100％,平均每个外植体产生8.52个不定根,平均根长为5.0cm;且进一步研究发现,与添加0.1mg·L-1 IBA相比,添加50μmol·L-1外源褪黑素能够进一步增加根长并促进幼苗长势;对滁菊幼苗田间移栽并干旱处理后,褪黑素处理组幼苗的长势优于IB A处理组.该研究为后期滁菊良种的种质保存、规模化繁育和遗传改良提供了技术支撑,同时为后期褪黑素在滁菊逆境胁迫中的应用研究奠定了基础.     

消费者旅游购物风险感知评价及差异研究——以厦门市为例

旅游购物是消费者普遍喜爱的活动,对目的地创收、形象、吸引力等产生深远影响,但频频发生的旅游购物风险问题已成为各旅游地发展旅游购物的重要阻碍。文章以厦门市为例,进行了旅游购物风险感知评价与差异研究。结果表明：旅游购物风险感知可以由财务、功能、时间、心理、身体、社交和服务风险7 个风险感知维度及18 个风险感知指标共同阐释;财务、时间、功能风险为关键风险感知维度,服务、心理、身体风险为次关键风险感知维度,社交风险为非关键风险感知维度;旅游购物风险感知指标可划分为7 个高风险感知指标、3 个可控风险感知指标、4 个低风险感知指标和4 个侥幸风险感知指标;不同性别消费者风险感知评价差异不显著,而不同年龄、受教育程度、月收入、职业的消费者的相应风险感知评价有显著差异。     

具幂指数型非线性项的发展型p-Kirchhoff方程及其稳态形式

考虑一类具幂指数型非线性项的p-Kirchhoff方程初边值问题及其稳态形式. 对于发展型方程, 采用位势井方法, 利用位势井的性质及积分估计, 刻画该问题一般整体解的渐近行为, 并证明位势井深的可达性; 对于稳态问题, 利用Lagrange乘数法给出其基态解的存在性.     

树脂催化下乙二醇与二元酸聚酯化反应动力学探讨

本文研究了在H型强酸性阳离子交换树脂存在下,邻苯二甲酸酐及顺丁烯二酸酐与乙二醇的酯化反应动力学。结果表明:在H型强酸性阳离子交换树脂存在下,上述反应的动力学过程不能用Lin在液体酸催化时的动力学方程—d[COOH]/dt=k″(COOH)~2来表示,但与动力学方程—d[COOH]/dt二k(k_h+k′_h)[COOH][OH]~2则有很好的一致性。     

The diploid genome sequence of an Asian individual

Here we present the first diploid genome sequence of an Asian individual. The genome was sequenced to 36-fold average coverage using massively parallel sequencing technology. We aligned the short reads onto the NCBI human reference genome to 99.97% coverage, and guided by the reference genome, we used uniquely mapped reads to assemble a high-quality consensus sequence for 92% of the Asian individual's genome. We identified approximately 3 million single-nucleotide polymorphisms (SNPs) inside this region, of which 13.6% were not in the dbSNP database. Genotyping analysis showed that SNP identification had high accuracy and consistency, indicating the high sequence quality of this assembly. We also carried out heterozygote phasing and haplotype prediction against HapMap CHB and JPT haplotypes (Chinese and Japanese, respectively), sequence comparison with the two available individual genomes (J. D. Watson and J. C. Venter), and structural variation identification. These variations were considered for their potential biological impact. Our sequence data and analyses demonstrate the potential usefulness of next-generation sequencing technologies for personal genomics.     

强化文本关联语义和多特征提取的重复缺陷报告检测模型

针对重复缺陷报告检测研究中存在语义长距离依赖以及缺陷报告特征的单一性问题,提出一种强化文本关联语义和多特征提取的重复缺陷报告检测模型。引入自注意力机制捕获缺陷报告文本序列内部的语义关联性,从而动态计算上下文语义向量进行语义分析,解决长距离依赖问题;利用隐含狄利克雷分布算法捕获缺陷报告文本的主题特征,同时针对缺陷报告的类别信息,构建一种特征提取网络计算类别差异特征;最后基于3类特征向量进行综合检测。实验结果表明,该模型实现了更优的检测性能。     

Chirp子脉冲频率步进雷达信号的探讨

本文理论分析了在频率步进雷达信号中采用线性调频信号（ｃｈｉｒｐ）作为子脉冲的可行性,重点讨论了目标运动对该种体制高距离分辨成像的影响,并提出了系统设计时的考虑。