logic

逻辑
  • 文章类型: Journal Article
    背景:女性生殖器整容手术在世界大部分地区发展迅速。专业组织已就这些做法的并发症和长期后果发出警告。为了能够采取正确的卫生政策,有必要知道为什么妇女决定执行这些程序。因此,本研究旨在发现伊朗女性生殖器整容手术所涉及的决策过程,并构建和验证健康公共政策的基于结果的逻辑模型.
    方法:本研究分三个阶段进行。在初始阶段,将使用Corbin和Strauss基础理论方法进行定性研究。该研究的参与者将是健康的女性,她们希望或已经接受了没有医学适应症的女性生殖器整容手术。在这个阶段,目的和理论抽样将指导招聘和数据收集。数据将通过半结构化访谈收集,现场笔记和个人互动的观察。数据将使用Corbin和Strauss(2015)的方法进行分析。使用MAXQDA2007软件管理数据分析过程。在第二阶段,基于第一阶段研究的结果,为健康的公共政策开发基于结果的逻辑模型,采访关键线人,并回顾该领域的文献结果。最后,在第三阶段,在一组专家在场的情况下,将通过名义组技术对所设计的程序进行验证。
    结论:这项研究的结果,通过确定女性与所研究现象相关的主要问题,现有的背景,参与者的反应和所采纳反应的后果,在设计一个符合伊朗文化特征的项目时非常重要。在这项研究中,将提出一个适合决策者的使用逻辑模型的程序,规划者和医疗服务提供者将在研究的社会文化背景下实施。
    女性生殖器美容程序是指一组美容程序,改变女性外生殖器的结构和健康外观,以改善性表现或身体形象。执行这些技术的愿望在世界大部分地区已经变得流行。然而,科学社会已经警告了效率,这些技术的有效性和副作用。根据这些观点,本研究旨在发现为伊朗妇女执行FGCP的决策过程,并构建和验证健康公共政策计划。这项研究将分三个阶段进行。首先,将进行定性研究,并与希望或已接受女性生殖器美容手术的健康女性进行访谈。在下文中,根据第一阶段的发现,采访主要举报人和文献综述,将提出一个程序来减少或防止这些程序,然后这个程序将被验证。使用设计的程序,保健医生将能够为妇女提供更有效的建议和指导,以做出正确和明智的决定。此外,该方案将使规划者和决策者能够采取措施减少对这些行动的需求,并通过改变和调整条件和背景,由妇女做出明智的决定。
    BACKGROUND: Female genital cosmetic procedures have grown rapidly in most parts of the world. Professional organizations have issued warnings about the complications and long-term consequences of these practices. To be able to adopt the right health policies, it is necessary to know why women decide to perform these procedures. Therefore, the present study will be aim to discover the decision-making process involved in performing female genital cosmetic procedures for Iranian women and construct and validate a results-based logic model for healthy public policy.
    METHODS: The present study was conducted in three phases. In the initial phase, a qualitative study will be conducted with the Corbin and Strauss ground theory approach. The participants in the study will be healthy women who desire or have undergone female genital cosmetic procedures without medical indications. In this phase, purposive and theoretical sampling will guide recruitment and data collection. The data will be collected via semi-structured interviews, field notes and observations of individual interactions. The data will be analysed using the approach of Corbin and Strauss (2015). MAXQDA 2007 software was used for managing the process of data analysis. In the second phase, the development of a results-based logic model for a healthy public policy is performed based on the findings of the first phase of the study, interviews with key informants and a review of the results of the literature in this field. Finally, validation of the designed program will be performed by the nominal group technique with the presence of a group of experts in the third phase.
    CONCLUSIONS: The findings of this study, by identifying women\'s main concerns related to the studied phenomenon, the existing context, participants\' reactions and the consequences of the adopted reactions, can be very important in designing a program that fits Iran\'s cultural characteristics. In this research, a program using a logical model will be presented that is suitable for policymakers, planners and healthcare service providers to be implemented in the social-cultural context of the study.
    Female genital cosmetic procedures refer to a group of cosmetic procedures that change the structure and healthy appearance of the female external genitalia to improve sexual performance or body image. The desire to perform these techniques has become popular in most parts of the world. However, scientific societies have warned about the efficiency, effectiveness and side effects of these techniques. According to these points, the present study aims to discover the decision-making process of performing FGCPs for Iranian women and to construct and validate a program for healthy public policy. This study will be performed in three stages. First, a qualitative study and interviews with healthy women who desire or have undergone female genital cosmetic procedures will be performed. In the following, based on the findings of the first stage, interviews with key informants and a review of literature, a program will be presented to reduce or prevent these procedures, and then this program will be validated. Using the designed program, healthcare practitioners will be able to provide women with more effective advice and guidance to make correct and informed decisions. In addition, this program will enable planners and policymakers to take steps to reduce the demand for these actions and make informed decisions by women by changing and adjusting the conditions and context.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Review
    Canadian specialty training programs are expected to deliver curriculum content and assess competencies related to the CanMEDS Scholar role. We evaluated our residency research program and benchmarked it against national norms for quality improvement purposes.
    In 2021 we reviewed departmental curriculum documents and surveyed current and recently graduated residents. We applied a logic model framework to assess if our program\'s inputs, activities, and outputs addressed the relevant CanMeds Scholar competencies. We then descriptively benchmarked our results against a 2021 environmental scan of Canadian anesthesiology resident research programs.
    Local program content was successfully mapped to competencies. The local survey response rate was 40/55 (73%). In benchmarking, our program excelled in providing milestone-related assessments, research funding, administrative, supervisory, and methodologic support, and requiring a literature review, proposal presentation, and local abstract submission as output. Acceptable activities to meet research requirements vary greatly among programs. Balancing competing clinical and research responsibilities was a frequently reported challenge.
    The logic model framework was easily applied and demonstrated our program benchmarked well against national norms. National level dialogue is needed to develop specific, consistent scholar role activities and competency assessments to bridge the gap between expected outcome standards and education practice.
    Les programmes de spécialité canadiens doivent proposer un contenu de formation en lien avec le rôle CanMEDS d’érudit et évaluer les compétences qui s’y attachent. Nous avons évalué notre programme de résidence en recherche par rapport aux normes nationales en la matière à des fins d’amélioration de la qualité.
    En 2021, nous avons examiné les documents du programme d’études du département et interrogé des résidents et des médecins récemment diplômés. Nous avons utilisé un modèle logique pour déterminer si les intrants, les activités et les extrants de notre programme couvraient adéquatement les compétences pertinentes liées au rôle CanMeds d’érudit. Nous avons ensuite comparé de façon descriptive nos résultats à une analyse du milieu des programmes de résidence canadiens en recherche en anesthésiologie effectuée la même année.
    Nous avons établi une correspondance entre le contenu du programme local et les compétences. Le taux de réponse à l’enquête était de 40/55 (73 %). D’après l’analyse comparative, notre programme se démarque par l’offre d’évaluations d’étape, de fonds de recherche, de soutien administratif, de supervision, d’orientation méthodologique, et, en ce qui concerne les extrants, par l’exigence d’une analyse documentaire, de la présentation d’une proposition et de la soumission d’un résumé à l’université. Les activités admissibles pour répondre aux exigences de la recherche varient considérablement d’un programme à l’autre. De nombreux répondants ont signalé la difficulté de concilier les responsabilités cliniques et de recherche.
    L’application du modèle logique a été aisée et elle a permis de montrer que notre programme respecte les normes nationales. Un dialogue au niveau national est nécessaire pour définir de manière précise et cohérente les activités et les évaluations des compétences en lien avec le rôle d’érudit afin de combler le fossé entre les normes quant aux résultats attendus et les pratiques des programmes.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    背景:阿片类药物在巴基斯坦通常用于治疗慢性非恶性疼痛;但缺乏关于阿片类药物使用的前体或动机的文献。
    目的:该研究从整体上探讨了导致阿片类药物不安全使用的因素,并确定了克服这些因素的策略。
    方法:使用访谈的探索性定性方法,使用焦点小组和非参与者观察性案例研究.面对面和虚拟地进行了访谈和焦点小组,并在伊斯兰堡和开伯尔·普赫图恩·库瓦省的社区药房进行了观察,巴基斯坦。数据来自4个利益相关者群体;药房政策制定者(n=11),慢性非恶性疼痛患者(n=14),医生(n=31)和社区药剂师(n=36)采用目的性危重病例抽样方法。使用反身主题分析对数据进行归纳分析,然后演绎映射到社会生态框架。使用解释构建技术,使用跨案例综合分析了非参与者的观察结果。对来自所有三种方法的数据进行三角剖分以建立逻辑模型。
    结果:确定的宏观(监管)因素,中观(对疼痛和阿片类药物的社会认知)和微观层面(不受控制的疼痛,自我药疗,健康素养)和策略从整体上提出,并用于开发逻辑模型,以预防和缓解目前导致阿片类药物不安全使用的因素。
    结论:该研究深入了解了导致药物阿片类药物转移的因素,并有助于指导国家和国际政策制定者未来的举措,以促进阿片类药物在巴基斯坦慢性非恶性疼痛的管理中的安全使用。
    BACKGROUND: Opioids are commonly used for the management of chronic non-malignant pain in Pakistan; but there is a lack of literature around precursors or motivators in the use of opioids.
    OBJECTIVE: The study holistically explored factors contributing towards the unsafe use of opioids and identifies strategies to overcome them.
    METHODS: Exploratory qualitative methods using interviews, focus groups and non-participant observational case studies were used. Interviews and focus groups were carried out face-to-face as well as virtually and observations were conducted in community pharmacies in Islamabad and Khyber Pukhtoon Khuwa province, Pakistan. Data were collected from 4 stakeholder groups; pharmacy policy makers (n = 11), people with chronic non-malignant pain (n = 14), doctors (n = 31) and community pharmacists (n = 36) by purposive critical case sampling method. Data were analysed inductively using reflexive thematic analysis and then deductively mapped to a social ecological framework. Non-participant observations were analysed using a cross case synthesis using explanation building technique. Data from all three methods were triangulated to develop a logic model.
    RESULTS: Identified factors at macro (regulation), meso (social perceptions of pain and opioids) and micro levels (uncontrolled pain, self-medication, health literacy) and strategies are presented holistically and were used to develop a logic model for the prevention and mitigation of factors currently causing unsafe use of opioids.
    CONCLUSIONS: The study provides an in-depth view of factors contributing towards diversion of pharmaceutical opioids and can help guide national and international policy makers in their future initiatives to promote safe use of opioids in the management of chronic non-malignant pain in Pakistan.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

    求助全文

  • 文章类型: Journal Article
    传统上,提出的基本生物过程的分子机制已经过实验测试。然而,由于太多的原因-设计困难,执行,解释关键实验,使用不同的实验模型和系统,在广泛不同的实验条件下进行研究,竞争机制之间的细微差别,科学问题的复杂性,以及一些科学家对与普遍持有的信念相反的发现的抵制-尽管在该领域进行了数十年的工作,但这并没有解决问题。作者想规定一种替代方法:测试竞争模型/机制是否遵守科学法律和原则,并检查逻辑错误。这样的测试在数学中相当普遍,物理学,和工程文献。Further,报告的实验测量不应小于所采用的测量技术的最小可检测值,并且应真实反映实际系统的功能,而无需不适用的外推。生物领域的进展将大大加快,采用这种方法避免了相当多的科学争论。已经回顾了氧化磷酸化(OXPHOS)中ATP合成基础领域的一些例子,这些例子也用于说明该方法。这种方法从未让作者在他35年的生物学机制经验中失望。这种思想上的转变应该可以节省大量的时间和资源,帮助引导研究努力解决正确的问题,并希望为年轻一代思想开放的生物科学家提供新的前景。
    Traditionally, proposed molecular mechanisms of fundamental biological processes have been tested against experiment. However, owing to a plethora of reasons-difficulty in designing, carrying out, and interpreting key experiments, use of different experimental models and systems, conduct of studies under widely varying experimental conditions, fineness in distinctions between competing mechanisms, complexity of the scientific issues, and the resistance of some scientists to discoveries that are contrary to popularly held beliefs-this has not solved the problem despite decades of work in the field/s. The author would like to prescribe an alternative way: that of testing competing models/mechanisms for their adherence to scientific laws and principles, and checking for errors in logic. Such tests are fairly commonly carried out in the mathematics, physics, and engineering literature. Further, reported experimental measurements should not be smaller than minimum detectable values for the measurement technique employed and should truly reflect function of the actual system without inapplicable extrapolation. Progress in the biological fields would be greatly accelerated, and considerable scientific acrimony avoided by adopting this approach. Some examples from the fundamental field of ATP synthesis in oxidative phosphorylation (OXPHOS) have been reviewed that also serve to illustrate the approach. The approach has never let the author down in his 35-yr-long experience on biological mechanisms. This change in thinking should lead to a considerable saving of both time and resources, help channel research efforts toward solution of the right problems, and hopefully provide new vistas to a younger generation of open-minded biological scientists.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    本研究的目的是分析专家进行的牙髓治疗中ProDesignLogic系统仪器骨折的发生率,除了确定牙科组,拱门,和根管三分之一,其中骨折发生更频繁。最初分析了数字X射线照片和病历,并使用ProDesignLogic系统仪器选择了2018年至2020年之间治疗的561颗牙齿(1302根管)。对这些数据进行了重新评估,以确定骨折的发生,并确定发生骨折的牙齿组和根管的三分之一。然后,数据采用Fisher精确检验进行统计学分析(p<0.05)。一般骨折率为8.5%和3.69%,考虑到治疗的牙齿和运河的数量,分别。下颌第一磨牙是与骨折发生最相关的牙齿(19.1%)。当比较拱门时,关于不同根管三分之一的骨折数量没有统计学差异(p=0.307)。然而,在两个拱门的根尖三分之一中,它们的频率更高(p=0.000)。ProDesignLogic系统仪器的骨折发生率相对较高,并且在磨牙的顶端三分之一中发生的频率更高。
    The aim of the present study was to analyze the incidence of fracture of ProDesign Logic system instruments in endodontic treatments performed by a specialist, in addition to identifying the dental group, arch, and the root canal thirds in which the fractures occurred more frequently. Digital radiographs and medical records were initially analyzed and resulted in the selection of 561 teeth (1302 canals) treated between 2018 and 2020, using the ProDesign Logic system instruments. These data were reassessed to determine the occurrence of fractures and identify the dental group and root canal thirds in which they occurred. Then, the data were statistically analyzed using the Fisher\'s Exact Test (p < 0.05). The general fracture rates were 8.5 and 3.69%, considering the number of teeth and canals treated, respectively. Mandibular first molars were the teeth most associated with the occurrence of fractures (19.1%). When the arches were compared, there was no statistical difference regarding the number of fractures in the different root canal thirds (p = 0.307). However, they were more frequent in the apical third in both arches (p = 0.000). The incidence of fracture of ProDesign Logic system instruments was relatively high and occurred more frequently in the apical third of molars.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

    求助全文

  • 文章类型: Journal Article
    尿失禁(UI)是主要的公共卫生问题。它影响了许多机构化的老年人。在文学中,这种现象是明确的。它的频率,危险因素,个人和社会成本,以及不同的治疗方法,被描述。然而,关于它的陈述的出版物很少,从病人和看护人的角度来看。然而,文献表明,更好地理解这种现象的社会表现可能是改善护理的载体。我们的目标是理解UI的感知,对其表示进行建模,并从保护的角度理解和表征行动逻辑。
    这将是一种混合方法,同时进行定量和定性研究。数据将通过100次半结构化访谈收集,来自4个人群的8个焦点小组和10,000个调查:机构老年人,看护者,照顾者和来自普通人群的个人。定性部分将手动和ATLAS进行分析。Ti软件,这将用于集中和组织收集的所有定性数据。对于定量部分的分析,将进行描述性统计分析和逻辑回归类型关联。这些分析将使用R软件来执行。然后,将进行三角分析方法的定量和定性信息的叠加和组合。该研究于2021年8月开始,并将持续到2022年6月。
    本研究方案于2021年6月1日获得笛卡尔伦理和研究委员会批准,IRB号为00012021-43。研究结果将发表在同行评审的期刊上,并在国家和国际会议上发表。
    该协议于2021年7月12日在研究注册中心注册,编号为researchregistry6965。
    Urinary incontinence (UI) is a major public health problem. It affects many institutionalised elderly people. In the literature, the phenomenon is well defined. Its frequency, risk factors, individual and social costs, as well as the different therapeutic approaches, are described. However, there are few publications on its representations, both from the point of view of the patient and that of the carers. However, the literature shows that a better understanding of the social representations of this phenomenon could be a vector for improving care. We aim at understanding the perception of UI, to model its representations and to understand and characterise the logics of action in terms of protection.
    This will be a mixed-method concurrent study with a quantitative and a qualitative component. Data will be collected through 100 semistructured interviews, 8 focus groups and 10 000 surveys from 4 populations: institutionalised elderly people, caregivers, carers and individuals from the general population. The qualitative part will be analysed both manually and with ATLAS.Ti software, which will be used to centralise and organise all qualitative data collected. For the analysis of the quantitative part, a descriptive statistical analysis and a logistic regression type association will be carried out. These analyses will be enforced using R software. Then, an overlay and combination of quantitative and qualitative information for the triangulation analytical approach will be carried out. The study started in August 2021 and will continue until June 2022.
    The study protocol was approved by the Descartes ethics and research committee on 1 June 2021, with the IRB number 00012021-43. The findings will be published in peer-reviewed journals and presented at national and international conferences.
    This protocol was registered with the Research Registry on 12 July 2021 and is numbered researchregistry6965.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

    求助全文

  • 文章类型: Journal Article
    The regression point displacement (RPD) design is a quasi-experiment (QE) that aims to control many threats to internal validity. Though it has existed for several decades, RPD has only recently begun to answer applied research questions in lieu of stronger QEs.
    Our primary objective was to implement within-study comparison (WSC) logic to create RPD replicates and to determine conditions under which RPD might provide estimates comparable to those found in validating experiments.
    We utilize three randomized controlled trials (two cluster-level, one individual-level), artificially decomposing or creating cluster structures, to create multiple RPDs. We compare results in each RPD treatment group to a fixed set of control groups to gauge the congruence of these repeated RPD realizations with results found in these three RCTs.
    RPD\'s performance was uneven. Using multiple criteria, we found that RPDs successfully predicted the direction of the RCT\'s intervention effect but inconsistently fell within the .10 SD threshold. A scant 13% of RPD results were statistically significant at either the .05 or .01 alpha-level. RPD results were within the 95% confidence interval of RCTs around half the time, and false negative rates were substantially higher than false positive rates.
    RPD consistently underestimates treatment effects in validating RCTs. We analyze reasons for this insensitivity and offer practical suggestions to improve the chances RPD will correctly identify favorable results. We note that the synthetic, \"decomposition of cluster RCTs,\" WSC design represents a prototype for evaluating other QEs.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

    求助全文

  • 文章类型: Journal Article
    医院到社区药房对出院患者的护理药物相关干预措施的转移旨在改善护理的连续性和患者的预后。在英格兰的一个地区已经提供了七年的这种干预。本研究报告了该干预措施的实施过程和保真度。
    医学研究委员会发布的过程评估指南已经通知了这项研究。通过与项目团队成员的初步半结构化访谈,开发了描述干预和因果假设的逻辑模型。对来自医院和社区药房的干预提供者进行了进一步的半结构化访谈,以及患者和公众代表。这些旨在调查干预实施过程和保真度。实施研究综合框架和干预保真度综合框架为访谈主题指南提供了信息,并使用归纳和演绎相结合的方法支持了主题框架分析。
    主题提供了有关干预保真度和实施的信息,这些信息映射到实施的子流程中:规划、执行,反思和评价,和订婚。受访者描述了缺乏培训等因素,意识,服务规范的清晰度,治理和监测以及信息和反馈,这在干预实施和次优干预保真度的过程中引起了重大问题。
    这为ToC干预的实施过程和保真度提供了深入的见解,以及现存的障碍和促进者。这些发现为类似干预措施的设计和实施提供了学习信息,为此类干预措施的障碍和促进者提供证据基础,并对有可能影响临床和经济结果评估的实施和影响机制进行深入描述。
    Hospital to community pharmacy transfer of care medicines-related interventions for inpatients discharged home aim to improve continuity of care and patient outcomes. One such intervention has been provided for seven years within a region in England. This study reports upon the implementation process and fidelity of this intervention.
    The process evaluation guidance issued by the Medical Research Council has informed this study. A logic model to describe the intervention and causal assumptions was developed from preliminary semi-structured interviews with project team members. Further semi-structured interviews were undertaken with intervention providers from hospital and community pharmacy, and with patient and public representatives. These aimed to investigate intervention implementation process and fidelity. The Consolidated Framework for Implementation Research and the Consolidated Framework for Intervention Fidelity informed interview topic guides and underpinned the thematic framework analysis using a combined inductive and deductive approach.
    Themes provided information about intervention fidelity and implementation that were mapped across the sub processes of implementation: planning, execution, reflection and evaluation, and engagement. Interviewees described factors such as lack of training, awareness, clarity on the service specification, governance and monitoring and information and feedback which caused significant issues with the process of intervention implementation and suboptimal intervention fidelity.
    This provides in-depth insight into the implementation process and fidelity of a ToC intervention, and the extant barriers and facilitators. The findings offer learning to inform the design and implementation of similar interventions, contribute to the evidence base about barriers and facilitators to such interventions and provides in-depth description of the implementation and mechanisms of impact which have the potential to influence clinical and economic outcome evaluation.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    Gender identity development services (GIDS) worldwide have seen a significant increase in referrals in recent years. Many of these referrals consist of children and young people (CYP) who experience gender-related distress. This study aims to improve understanding of outcomes of CYP referred to the UK GIDS, specifically regarding gender identity, mental health, physical health and quality of life. The impact of factors such as co-occurring autism and early social transition on outcomes over time will be explored.
    This is a prospective cohort study of CYP aged 3-14 years when referred to the UK GIDS. Eligible participants will be ≤14 years at the time their referral was accepted and will be on the waitlist for the service when baseline measures are completed. Children aged under 12 years will complete the measures in an interview format with a researcher, while young people aged 12 years and over and their parents/caregivers will complete online or paper-based questionnaires. Participants will complete follow-up measures 12 months and 24 months later. The final sample size is expected to be approximately 500. Logistic regression models will be used to explore associations between prespecified explanatory variables and gender dysphoria. Appropriate regression models will also be used to investigate explanatory variables for other outcomes. Subgroup analyses based on birth-assigned gender, age at referral and co-occurring autistic traits will be explored.
    The study has been approved by the Health Research Authority and London - Hampstead Research Ethics Committee (reference: 19/LO/0857). The study findings will be published in peer-reviewed journals and presented at both conferences and stakeholder events. Findings will be used to inform clinical practice.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    This paper explores the statistical distribution characteristics of coating film thickness, so as to present a new method for determining coating endpoint based on 3σ criterion and logic regression. Firstly, the spectrum and thickness of 4 batch samples were collected. Secondly, the spectral range of normal products was obtained by 3σ criterion, with the spectral feature NI as the number of test spectrum in the above range. Then, the model based on 3σ criterion and logic regression was built according to the best condition in K-fold cross-validation and the determined threshold of qualified rate in the coating endpoint. Finally, the qualified rate of test set samples at different time points was calculated by the above model, and the above change trend and the threshold value were combined to determine the coating endpoint. The results of KS analysis showed the distribution of thickness of the qualified products followed the normal distribution(P=0.081>0.05). The accuracy of the coating endpoint determination was as high as 100% by the model based on 3σ criterion and logic regression when the determined threshold of qualified rate was 90%. Therefore, the 3σ criterion was feasible to the research of coating eligibility. This paper reveals certain random phenomena in the coating process, and the method features a high accuracy, quick analysis and a good interpretability, which provides a reference for online detection and qualify evaluation in future.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

    求助全文

公众号