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"Harrison, P."
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A new data set of soil mineralogy for dust-cycle modeling
The mineralogy of airborne dust affects the impact of dust particles on direct and indirect radiative forcing, on atmospheric chemistry and on biogeochemical cycling. It is determined partly by the mineralogy of the dust-source regions and partly by size-dependent fractionation during erosion and transport. Here we present a data set that characterizes the clay and silt-sized fractions of global soil units in terms of the abundance of 12 minerals that are important for dust–climate interactions: quartz, feldspars, illite, smectite, kaolinite, chlorite, vermiculite, mica, calcite, gypsum, hematite and goethite. The basic mineralogical information is derived from the literature, and is then expanded following explicit rules, in order to characterize as many soil units as possible. We present three alternative realizations of the mineralogical maps, taking the uncertainties in the mineralogical data into account. We examine the implications of the new database for calculations of the single scattering albedo of airborne dust and thus for dust radiative forcing.
Journal Article
Resource colimitation governs plant community responses to altered precipitation
Ecological theory and evidence suggest that plant community biomass and composition may often be jointly controlled by climatic water availability and soil nutrient supply. To the extent that such colimitation operates, alterations in water availability caused by climatic change may have relatively little effect on plant communities on nutrient-poor soils. We tested this prediction with a 5-y rainfall and nutrient manipulation in a semiarid annual grassland system with highly heterogeneous soil nutrient supplies. On nutrient-poor soils, rainfall addition alone had little impact, but rainfall and nutrient addition synergized to cause large increases in biomass, declines in diversity, and near-complete species turnover. Plant species with resource-conservative functional traits (low specific leaf area, short stature) were replaced by species with resource-acquisitive functional traits (high specific leaf area, tall stature). On nutrient-rich soils, in contrast, rainfall addition alone caused substantial increases in biomass, whereas fertilization had little effect. Our results highlight that multiple resource limitation is a critical aspect when predicting the relative vulnerability of natural communities to climatically induced compositional change and diversity loss.
Journal Article
Skin Cleansing without or with Compromise: Soaps and Syndets
Products designed to cleanse the skin commonly do so through surfactant action, which leads to the lowering of the surface tension of the skin to facilitate the removal of dirt from its surface. Skin cleansers generally come in one of two types: soap-based and synthetic detergents, or syndets. While the latter can effectively maintain the native skin structure, function and integrity, the former tends to negatively affect the skin by causing barrier disruption, lipid dissolution and pH alteration. Despite this, soap is still often preferred, possibly due to the negative connotations around anything that is not perceived as ‘natural’. It is, therefore, important that the science behind cleansers, especially those designed for the maintenance of healthy skin and the management of common skin conditions such as eczema, be understood by both formulators and end-users. Here, we carefully weigh the advantages and disadvantages of the different types of surfactant—the key ingredient(s) in skin cleansers—and provide insight into surfactants’ physicochemical properties, biological activity and potential effects. Fine-tuning of the complex characteristics of surfactants can successfully lead to an ‘optimal’ skin cleanser that can simultaneously be milder in nature, highly effective and beneficial, and offer minimal skin interference and environmental impact.
Journal Article
الثقافات وقيم التقدم
هذه مجموعة دراسات حوارية مثيرة للجدل تعالج مسائل صعبة نحن بحاجة إلى أن نتأملها بعقل ناقد. هل هناك ثقافات أفضل من ثقافات تعزز قيم الحرية والرخاء والتقدم والعدالة؟ وهل الثقافات أو القيم الثقافية هي وحدها المسئولة ؟ وهل هي جبلية من ثوابت الطبيعة البشرية والمجتمعات ؟ أو قابلة للتطوير والتغيير، ومن ثم تكون الدعوة لدى الشعوب المختلفة تطويراً حضارياً قرين تغيير ثقافي على نحو ما تؤكد شهادات التاريخ ؟ الدراسات الواردة ليست توجهاً واحداً. ثراء الكتاب في تباين وجهات النظر الي حد التعارض. إنها مع وضد، تنحاز إلى هنا أو إلي هناك، ولكنها تكشف عن محتوى صراع ساخن، وعن حرب ثقافية. نحن ضحايا ؛ إذ نلوذ بالصمت أو نلوذ بالسلف. والكتاب في ترجمته العربية ليس دعوة إلي تبنى فكر، بل حفزاً للقارئ العربي إلى السؤال النقدي عن ثقافتنا، ودعوة إلى الإفلات من وهم نعيش أسرى له هو الحفاظ على ثوابت الثقافة، كأن الثقافة بنية لا تاريخية أحادية الكيان، لا تتغير في الزمان، ليست منتج فعل متطور، وحصاد تفاعل دينامي انفصالاً واتصالاً كنهج الحياة الجدلي الأبدي.
Book
Schizophrenia genes, gene expression, and neuropathology: on the matter of their convergence
This review critically summarizes the neuropathology and genetics of schizophrenia, the relationship between them, and speculates on their functional convergence. The morphological correlates of schizophrenia are subtle, and range from a slight reduction in brain size to localized alterations in the morphology and molecular composition of specific neuronal, synaptic, and glial populations in the hippocampus, dorsolateral prefrontal cortex, and dorsal thalamus. These findings have fostered the view of schizophrenia as a disorder of connectivity and of the synapse. Although attractive, such concepts are vague, and differentiating primary events from epiphenomena has been difficult. A way forward is provided by the recent identification of several putative susceptibility genes (including neuregulin, dysbindin, COMT, DISC1, RGS4, GRM3, and G72). We discuss the evidence for these and other genes, along with what is known of their expression profiles and biological roles in brain and how these may be altered in schizophrenia. The evidence for several of the genes is now strong. However, for none, with the likely exception of COMT, has a causative allele or the mechanism by which it predisposes to schizophrenia been identified. Nevertheless, we speculate that the genes may all converge functionally upon schizophrenia risk via an influence upon synaptic plasticity and the development and stabilization of cortical microcircuitry. NMDA receptor-mediated glutamate transmission may be especially implicated, though there are also direct and indirect links to dopamine and GABA signalling. Hence, there is a correspondence between the putative roles of the genes at the molecular and synaptic levels and the existing understanding of the disorder at the neural systems level. Characterization of a core molecular pathway and a ‘genetic cytoarchitecture’ would be a profound advance in understanding schizophrenia, and may have equally significant therapeutic implications.
Journal Article
كتاب أكسفورد المختصر في الطب النفسي
هذا الكتاب غني عن التعريف فهو معروف على المستوى الدولي والعربي منذ صدور طبعته الأول وحتى الطبعة الحالية السابعة، والتي تحتوي على الطب النفسي بشكله المعاصر. كتاب أكسفورد المختصر في الطب النفسي معترف به بشكل واسع، هو كتاب أساسي للمتدربين في الطب النفسي، ويقف هذا الكتاب متميزا فوق التنافس. واكتسب زخما على مدى سبع طبعات، يتميز الكتاب بالسلاسة والسهولة، السلطة والبصيرة وهذه نادرا ما تجدها في الكتب المرجعية، مما يجعل عملية اكتساب المعلومات منة فعالة وممتعة. الكتاب يقدم استهلالا لكل المواضيع السريرية، والاختصاصات الفرعية، والاضطرابات النفسية الأساسية الكبيرة المطلوبة للأطباء المتدربين في الطب النفسي. طول صفحات الكتاب، يؤكد المؤلفون على المهارات السريرية الأساسية المطلوبة لاستكمال تقييم وفهم حالة المريض. مناقشة أشكال العلاج المتاحة تشمل بالإضافة إلى الدلائل العلمية المشاكل العملية في تدبير المرضى في إطار الأسرة والمجتمع. تم إعطاء الانتباه الكامل للجوانب الأخلاقية والقانونية من خلال المقاربة المستندة على الدليل للممارسة التي تقدم في هذا الكتاب. الكتاب يعطي ظهورا متساويا للتقسيم الدولي العاشر للأمراض، والتقسيم الأمريكي الخامس، وهذا يجعل الكتاب مفيدا للممارسين في كل أنحاء العالم، وهذا التوجه للعالمية تم تدعيمه بفصل عن الصحة النفسية العالمية. ولاستعراض الكتاب وفصوله فإنه يقع في ستة وعشرين فصلا، تغطي كافة جوانب الطب النفسي بداية بالأعراض والعلامات النفسية التي تساعد في التعرف على الاضطرابات المختلفة من شكوى المريض ومن يحيط به إلى المظاهر التي يراها الطبيب أثناء الفحص، إلى التصنيف بأشكاله وأنواعه مع التركيز على التصنيف الدولي العاشر والأمريكي الخامس، والتقييم للحالة الذي لا بد أن يقوم به من يقيم الحالة، فالأخلاقيات والقوانين المدنية ذات العلاقة.
Book
Links between tropical Pacific seasonal, interannual and orbital variability during the Holocene
The El Niño/Southern Oscillation (ENSO) is the leading mode of interannual climate variability. However, it is unclear how ENSO has responded to external forcing, particularly orbitally induced changes in the amplitude of the seasonal cycle during the Holocene. Here we present a reconstruction of seasonal and interannual surface conditions in the tropical Pacific Ocean from a network of high-resolution coral and mollusc records that span discrete intervals of the Holocene. We identify several intervals of reduced variance in the 2 to 7 yr ENSO band that are not in phase with orbital changes in equatorial insolation, with a notable 64% reduction between 5,000 and 3,000 years ago. We compare the reconstructed ENSO variance and seasonal cycle with that simulated by nine climate models that include orbital forcing, and find that the models do not capture the timing or amplitude of ENSO variability, nor the mid-Holocene increase in seasonality seen in the observations; moreover, a simulated inverse relationship between the amplitude of the seasonal cycle and ENSO-related variance in sea surface temperatures is not found in our reconstructions. We conclude that the tropical Pacific climate is highly variable and subject to millennial scale quiescent periods. These periods harbour no simple link to orbital forcing, and are not adequately simulated by the current generation of models.
The frequency and amplitude of the El Niño/Southern Oscillation varied during the Holocene. A comparison of proxy records and model simulations suggests that any link between orbital forcing and this variability is either complex or non-existent.
Journal Article