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Physics and chemistry education foundation ponder

admin — Mon, 26 Jul 2010 14:59:41 +0000

In history, the most skilled of mankind’s used is physics and chemical techniques. It has philosophy background of machinery and guest opposite, so that modern technology has made the industrial revolution get the great achievement. This article briefly analysis the impact for physics and Chemistry Problems education and ideology.

Current the achievement of Physics help and Chemistry development in online tutoring is more surprising, and it has supported the technical principle powerfully. The further facilitates this idea for Physics problem solver. Also has intense influence the Chemistry help fields. These suitable education foundation already become a important component of online tutoring industry.

The nimble online tutoring education can overcame the study time and the place limit, all students has been possible to carry on the study through the network conveniently. They can selection Chemistry Answers and broadcast courseware, avoided wastes on time, energy and money. If they are looking for Physics Answers, just to arrange the study progress independently, then it is easy to resolve Physics Problems. We learn physics and chemistry education foundation technology is aimed at the actual teaching, as for me, I believe students will enjoyed the physics and chemistry education foundation, and fully pleasure the network study.

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heart and liver transplant recipients Lung cancer risk high

admin — Sat, 01 May 2010 16:05:29 +0000

Heart and liver transplant recipients are at particularly high risk of developing lung cancer after receiving the donated organ, researchers report at the 2nd European Lung Cancer Conference. They are advising doctors to screen for such cancers in these patients to maximize the chance of detecting the malignancy early.

Doctors have known for decades that the immunosuppressive drugs given to transplant patients increase their risk of developing new cancers. In transplant patients, the risk of developing a malignant tumor ranges from 4% to 18% and may be 100-fold higher than in the general population. The most common malignancies after transplantation are cancers of the lips and skin, lymphoproliferative disorders and Kaposi’s sarcoma.

In a new study, French researchers studied the risk of developing lung cancer in patients who received different types of solid organs. Theirs is the largest study to date exploring the development of lung cancer in transplant recipients.

The researchers followed a group of 2,831 patients who received organ transplants at Toulouse Hospital between February 1984 and September 2006. Overall, 0.85% of them developed a lung cancer after transplant.

“We observed that 10 lung cancers occurred after kidney transplantation (0.5%), 8 after liver transplantation (1.3%) and 6 after heart transplantation (2.8%). This difference is statistically significant,” said Dr Julien Mazieres, the study coordinator.

“The high incidence of lung cancer in heart transplant and liver transplant recipients may be because more of these patients have a heavy smoking history compared to kidney transplant recipients,” he said. The average number of packs per year was 75.2 for heart-transplant patients, 40 for liver-transplant recipients and 28.5 for kidney-transplant recipients.

The researchers say that transplant patients should be screened for expected cancers for which early detection and treatment is associated with a better prognosis. This is particularly true for skin cancers.

Doctors should also consider screening for lung cancer, they say. “We can reasonably think that a close follow-up including chest examination and X-ray is easy to do and useful,” Dr Mazieres said. “At least, physicians taking care of transplant recipients should have in mind the increased risk of cancer and integrate this risk factor in their follow-up to improve the survival of these patients.”

Renewable energy is the driving force of economic

admin — Fri, 26 Mar 2010 03:46:53 +0000

With the country’s development and growth, demand for energy will increase rapidly，meet the needs of growing economy. How can we meet this rising demand? the renewable energy should be first considered. The use of renewable energy for lighting, telecommunications, irrigation and other agricultural needs, as well as cottage industries, water heating, cooking and so on.

However, there are many obstacles to the development of renewable energy sources, including start-up costs are high, technical personnel and inadequate infrastructure, as well as a lack of energy policy and so on. Renewable energy technologies are an advanced technology. Many countries are now trying to make this technology for cooking, food drying, and heating and other daily needs. But to promote this technology and to provide technical guidance related to a lot of work to be done. The http://www.nviro.com hold the development of renewable energy technologies and patented.

Renewable energy can also be the local industrial and agricultural use, such as the use of opportunity fuels and clean coal, therefore, the development of renewable energy has a bright future. With residents, communities, and industrial demand for energy is increasing. In these areas should absorb the good experience of other countries and regions, promote and implement renewable energy projects.

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how to choose ugg boots

admin — Tue, 17 Nov 2009 17:32:01 +0000

Many places have began to snow, so it is time to move out the ugg boots. Ugg boots Is not only warm but also fashionable, It has become essential in winter. But how to choose good quality? This is a difficult problem.

There are many inferior products or counterfeit products flooding the market. When you buying snow boots, you can identified pure ugg by inspect, touch and smell.

First adopt inspecting. Careful observation ugg, pure ugg’s coat is shiny bright and soft, and inferior goods are bleak colors, easy to fade. if it is made of a different color, you should pay attention to the existence of the same color aberration. You also need to check the flatness and density. Second is touch. Because of the ugg boots sale high-density, high-quality, so you will feels fine, there is a sense of velvet. while inferior feel rough, sticky astringent. Separated ugg boots by hand to see if there is hair cracks, skin, etc. You can also gently pull fur to see if hair lossing. Third by smelling. High-quality ugg without any smell, while inferior ugg emit unpleasant smell.

Finally note, ugg boots can not be washed, and should be placed in ventilated dry place.

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基因差异造就真爱

admin — Tue, 26 May 2009 19:10:03 +0000

俗话说，“物以类聚，人以群分”，因而我们以为人们更愿意选择那些与自己相似的人做伴侣。但一份最新的研究却表明：如果双方的基因差异很大，他们反而更可能成为恋人，而且，选择那些拥有不同基因的人做伴侣，可以提高后代的免疫能力。

巴西巴拉那联邦大学的Maria da Graca Bicalho教授研究了152对已婚夫妇，她发现，在其中90对已婚夫妇的基因中，其染色体某个关键区域的基因非常不同。

这个名叫主要组织相容性复合体（MHC）的基因是免疫系统的一部分，这是科学家首次发现该基因可能在婚姻中起重要作用。Bicalho教授表示，拥有健康后代的潜意识在选择伴侣时非常重要。

研究人员也认为，MHC基因除了有助于帮助人体战胜疾病，还可能对身体气味有微妙的影响，而体味也是决定异性是否互相吸引的关键因素。

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抗病毒药物何以抗击甲型H1N1流感

admin — Tue, 19 May 2009 02:51:56 +0000

在甲型H1N1流感病毒肆虐全球之际，人类该如何应对？最新出版的《科学》杂志发表文章指出，在甲型H1N1流感疫苗数月内无望问世的情况下，两种抗病毒药物达菲和瑞乐沙是目前遏制甲型H1N1流感病毒的最好选择。但是在世界范围内，这两种药物的储存量太少，不足以在流感大暴发的情况下为每个人提供保护；而健康官员们则担心这种病毒可能会对这些药物产生抗药性。

达菲（Tamiflu）是瑞士罗氏公司生产的抗病毒药物，瑞乐沙（Relenza）则是由葛兰素史克公司生产的抗病毒药物。4 月28日，美国疾病预防和控制中心（CDC）表示，试验显示，这两种抗病毒药物对甲型H1N1流感具有疗效。CDC测试了13位甲型H1N1流感患者的病毒样本对抗病毒药物的反应，结果显示，达菲和瑞乐沙对甲型H1N1流感病毒样本的感受性强，表明其在抵御甲型H1N1流感疾病方面可能有效，而所有甲型 H1N1流感样本对较早的抗病毒药物金刚烷胺（Amantadine）和金刚乙胺（Rimantadine）则有抗药性。

在一个流感暴发的季节，应该储存多大剂量的抗病毒药物呢？《科学》的文章指出，这取决于流感暴发的严重程度和所使用的药物。到目前为止，世界各国大约储备有2.5亿剂抗病毒药物。一个可以参照的数据是，在1918年至1919年的流感大暴发中，大约有8亿人患病。

然而，在过去两周的新闻发布会上，当抗病毒药物短缺的问题被提到桌面上时，健康官员们对抗病毒药物的作用嗤之以鼻。欧洲疾病预防和控制中心的安古斯·安柯斯说：“人们太关注抗病毒药物了，比如抗生素。”

但是，许多流感专家不同意这种看法。安妮·莫丝科娜是纽约市威尔康奈尔医学院的儿科传染病医生和病毒学家，她强调，现实情况是严重的流感可导致第二次感染如肺炎，专家们相信，这种第二次感染可以解释1918年流感大暴发为何死亡人数众多。莫丝科娜和其他专家指出，抗病毒药物是流感暴发时预防死亡和疾病的关键因素。

达菲和瑞乐沙均能遏制一种名为神经氨（糖）酸苷酶的病毒蛋白质的功能，因此，它们能防止病毒离开细胞表面并向肺部组织扩散。患病早期用药效果最佳，特别是在病毒扩散到肺部之前。

目前还不清楚这些药物在遏制病毒在人际间传播的有效性，但绝大多数流感专家相信，它们通过阻断病毒的复制而缩短患病时间。当健康人服用这些药物时，他们患流感的风险降低了70%到80%。然而，在是否预防性地发放药物问题上，流感专家持不同意见。美国CDC目前的建议是，只针对密切接触H1N1患者的人群和本身是高风险的人群采取预防性用药措施，高风险人群包括孕妇、儿童和接触患者的保健人员。

《科学》的文章指出，向众多健康人群提供药物有两个问题。第一，因为新病毒的毒性相对温和，用有限的储备来预防它的发生未必是明智之举；第二，病毒可能会对其中一种或两种药物产生抗药性。后一点特别令人担心，因为在过去几年中，一种季节性流感病毒——人类H1N1亚型——出乎意料地对达菲产生了完全的抗药性。

美国华盛顿大学的生物统计学家艾拉·隆吉尼说，一个迫在眉睫的问题是：如何布署这两种抗病毒药物才可以使抗药性形成的可能性最小化？一个可能的办法是同时用达菲和瑞乐沙进行治疗，这样H1N1就更难形成抗药性。隆吉尼相信，数据模式将有助于精确确定如何布置这些药物，从而最小化抗药性形成的机会。但是，因为达菲只能口服，而瑞乐沙必须是吸入，因此各国到目前为止大量储存的都是达菲，现在，大家又担心病毒会对达菲形成抗药性。

《科学》的文章指出，根据最有希望的数据模式来分发药物也许只是一个白日梦，药物的分发最终将随着疾病的流行情况而改变。现在，制药公司正在竞相扩大药物的生产量。

via：Science 8 May 2009:DOI: 10.1126/science.324_705

What Role for Antiviral Drugs?

Jennifer Couzin-Frankel

When it comes to treatment, there’s good news and bad news about the new H1N1 swine flu strain circling the globe. Two antiviral drugs can squelch it and are currently the best defense, given that a vaccine will not be ready for months. But stocks of Roche’s Tamiflu (oseltamivir) and GlaxoSmithKline’s Relenza (zanamivir) are too small to protect everyone in a worst-case scenario outbreak; health officials also worry that the virus could become resistant to the drugs.

甲型H1N1流感病毒基因标记研究

admin — Mon, 11 May 2009 06:32:33 +0000

有记载的人类社会发展历程中，曾经有过几次流感大流行。这些灾难都是由某些致命流感病毒引发的，那么，这次引爆全球的甲型H1N1病毒是否也具有致命流感病毒的某些标记呢？美国科学家在最新一期《BMC Microbiology》上发表研究报告说，经过与以往造成流感大流行的致命流感病毒进行对比，他们认为甲型H1N1流感病毒并不像人们担心的那么严重。

美国利弗莫尔劳伦斯国家实验所的乔纳森·艾伦和汤姆·斯莱扎克从被保留下来的、造成以往几次流感大流行的病毒毒株中鉴别出34种基因标记物，这些标记物与病毒宿主特异性和高致死率有关，影响着流感的严重程度；与此同时，他们从甲型H1N1流感病毒毒株样本中鉴别出17种影响流感严重程度的基因标记物。在对这些基因标记物进行对比后发现，甲型H1N1流感病毒样本中的基因标记物与致命流感病毒中的基因标记物没有相似性。

研究人员认为，这表明甲型H1N1流感病毒缺少以往出现的致命流感病毒所具有的特性。但他们也同时强调说，这一研究结果并不表示目前的甲型H1N1流感不严重，而且，对此作出定论还有待进一步研究。

BMC Microbiology 2009, 9:77doi:10.1186/1471-2180-9-77

Conserved amino acid markers from past influenza pandemic strains

Jonathan E Allen , Shea N Gardner , Elizabeth A Vitalis and Tom R Slezak

Abstract

Background

Finding the amino acid mutations that affect the severity of influenza infections remains an open and challenging problem. Of special interest is better understanding how current circulating influenza strains could evolve into a new pandemic strain. Influenza proteomes from distinct viral phenotype classes were searched for class specific amino acid mutations conserved in past pandemics, using reverse engineered linear classifiers.

Results

Thirty-four amino acid markers associated with host specificity and high mortality rate were found. Some markers had little impact on distinguishing the functional classes by themselves, however in combination with other mutations they improved class prediction. Pairwise combinations of influenza genomes were checked for reassortment and mutation events needed to acquire the pandemic conserved markers. Evolutionary pathways involving H1N1 human and swine strains mixed with avian strains show the potential to acquire the pandemic markers with a double reassortment and one or two amino acid mutations.

Conclusion

The small mutation combinations found at multiple protein positions associated with viral phenotype indicate that surveillance tools could monitor genetic variation beyond single point mutations to track influenza strains. Finding that certain strain combinations have the potential to acquire pandemic conserved markers through a limited number of reassortment and mutation events illustrates the potential for reassortment and mutation events to lead to new circulating influenza strains.

DNA分析揭示人类起源于纳米比亚

admin — Thu, 07 May 2009 06:11:56 +0000

科学家通过DNA分析指出，人类起源于安哥拉—纳米比亚边境，几千年来一直在纳米比亚狩猎采集的Bushmen或也称San people是地球上最古老的人类。该研究同时也表明，3/4的非洲裔美国人可能都来自于西非，且整个非洲大陆人群中存在着巨大的遗传差异。该研究成果发表在最新出版的《Science》上。

美国宾夕法尼亚大学遗传学家萨拉－提史科夫 Dr Tishkoff 领导了此项历时10年的研究。该国际研究团队收集了121个非洲群落共3000多个现代非洲人、4个非洲裔美国人的DNA样本，并对样本进行了对比分析。研究表明，121个非洲群落都来自于14个先祖群落。

研究显示，大约5万年前，150个非洲人首次离开非洲大陆，从此分散到世界各地。研究人员在苏丹人的DNA中发现的遗传标记显示，苏丹人同这些非洲人密切相关。研究还发现，大约71%%的非洲裔美国人、13%%到15%%的欧洲人和少量亚洲人的祖先都来自于西非。

加州大学的克里斯托弗—埃雷说，只有20%%的非洲人直接去了北美，其他非洲人则先去了西印度群岛。美国乔治亚州和南卡罗来纳州的非洲裔美国人的祖先可能来自于塞拉利昂和几内亚。

该研究除了提供人们等待已久的有关非洲人和非洲裔美国人的进化史资料之外，还为许多其他研究提供了基础。

美国范德比特大学的斯科特—威廉姆斯表示，该研究可以帮助遗传流行病学家找到最能说明问题的人群来做“病例对照相关性研究”，建立疾病变异的模式，找出哪个基因容易让某个群体患上特定的疾病，以设计出对抗某些疾病的更佳办法。进化遗传学家也可以应用该研究数据来调查诸如现代人是在何时何地在非洲进化的，以及他们迁徙出非洲的人群大小等问题。

人用猪流感疫苗研制还需时日

admin — Wed, 29 Apr 2009 03:20:49 +0000

昨天许多媒体迫不及待的刊登了“湖北已研制出猪流感疫苗”的报道，经中国畜牧兽医学会理事长华中农业大学陈焕春院士澄清，“这种说法有误导。”陈先生强调，华中农大所研制的疫苗只是针对普通流感病毒，对此次暴发的病毒肯定无效。与传统普通猪流感病毒相比，目前暴发的猪流感病毒是一个新型病毒，他对这个全新病毒的了解和普通人并无二致。

流感疫苗是非常容易研制，但首先必须有确定的毒株。得到病毒毒株后，经过细胞培养、大规模纯化培养等步骤后，可以得到病毒灭活疫苗，再经过动物或人体保护性实验，就能对普通人群进行注射。

有报道说，美国生物制药公司VaxInnate总裁艾伦·肖日前表示，针对墨西哥猪流感新型病毒的疫苗样品有望在4周内研制成功。

其实，人感染猪流感的症状与普通人流感相似，但猪流感是可防、可控、可治的。一般条件下，70℃以上高温即可杀死猪流感病毒。因此，处理得当的熟猪肉制品完全可以放心食用。

海洋藻类的绿色基因

admin — Wed, 15 Apr 2009 15:26:57 +0000

来自《科学》杂志的报道，科学家在一项研究中发现，一组古老的绿藻具有令人诧异的基因多元性，而这可能为人们提供绿色植物是如何进化的线索。

Alexandra Worden及其同僚对两株Micromonas海藻的基因组进行了测序。该海藻株是陆地植物的远古亲缘植物，它们存在于全世界各地的海洋中。文章的作者说，这些基因组揭露了这些远祖海藻所启动的数十亿年的植物进化和地球被绿化的轨迹特征。该国际研究团队发现，在这两株海藻中存在着始料未及的遗传变异水平，它们所遵循的是不同的进化途径。

研究人员还发现了重要细胞器及细胞过程的标志，如基因沉默及硫胺的生物合成。其中一株看来是独特转位因子的一个重要来源，这种转位因子过去在对Sargasso Sea的一个“宏基因组”的研究中曾被发现。正如John Archibald在一篇相关的Perspective中所写的，这些结果可帮助解释为什么该基因“工具包”可能已经存在于当今陆地植物和绿藻的祖先植物之中。

已知最小的真核生物Micromonas之一的电子断层切片（ 0.5微米厚）。

资料来源: A.Z. Worden, T. Deerinck, M. Terada, J. Obiyashi, and M. Ellisman (MBARI and NCMIR)

新开博客 | 二手科学家 » 研究进展

Physics and chemistry education foundation ponder

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heart and liver transplant recipients Lung cancer risk high

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抗病毒药物何以抗击甲型H1N1流感

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甲型H1N1流感病毒基因标记研究

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