Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
97,261
result(s) for
"De Marco, Marco"
Sort by:
Evaluating collinearity effects on species distribution models: An approach based on virtual species simulation
The increasing use of species distribution modeling (SDM) has raised new concerns regarding the inaccuracies, misunderstanding, and misuses of this important tool. One of those possible pitfalls - collinearity among environmental predictors - is assumed as an important source of model uncertainty, although it has not been subjected to a detailed evaluation in recent SDM studies. It is expected that collinearity will increase uncertainty in model parameters and decrease statistical power. Here we use a virtual species approach to compare models built using subsets of PCA-derived variables with models based on the original highly correlated climate variables. Moreover, we evaluated whether modelling algorithms and species data characteristics generate models with varying sensitivity to collinearity. As expected, collinearity among predictors decreases the efficiency and increases the uncertainty of species distribution models. Nevertheless, the intensity of the effect varied according to the algorithm properties: more complex procedures behaved better than simple envelope models. This may support the claim that complex models such as Maxent take advantage of existing collinearity in finding the best set of parameters. The interaction of the different factors with species characteristics (centroid and tolerance in environmental space) highlighted the importance of the so-called \"idiosyncrasy in species responses\" to model efficiency, but differences in prevalence may represent a better explanation. However, even models with low accuracy to predict suitability of individual cells may provide meaningful information on the estimation of range-size, a key species-trait for macroecological studies. We concluded that the use of PCA-derived variables is advised both to control the negative effects of collinearity and as a more objective solution for the problem of variable selection in studies dealing with large number of species with heterogeneous responses to environmental variables.
Journal Article
Neuronal activity is required for the development of specific cortical interneuron subtypes
Active migrating neurons
Interneurons migrate long distances before settling into a specific microcircuit. Because these cells are known to participate in correlated network activity, it is possible that electrical inputs may influence migration and integration. By manipulating neuronal activity in subsets of developing interneurons, Fishell and colleagues find that proper migration does indeed depend on this activity, involving a transcription-factor signalling pathway specific to those interneuron cell types.
Electrical activity has been shown to regulate development in a variety of species and in various structures
1
, including the retina
2
,
3
,
4
, spinal cord
5
,
6
and cortex
5
. Within the mammalian cortex specifically, the development of dendrites and commissural axons in pyramidal cells is activity-dependent
7
,
8
. However, little is known about the developmental role of activity in the other major cortical population of neurons, the GABA-producing interneurons. These neurons are morphologically and functionally heterogeneous and efforts over the past decade have focused on determining the mechanisms that contribute to this diversity
9
,
10
,
11
. It was recently discovered that 30% of all cortical interneurons arise from a relatively novel source within the ventral telencephalon, the caudal ganglionic eminence (CGE)
11
,
12
. Owing to their late birth date, these interneurons populate the cortex only after the majority of other interneurons and pyramidal cells are already in place and have started to functionally integrate. Here we demonstrate in mice that for CGE-derived reelin (Re)-positive and calretinin (Cr)-positive (but not vasoactive intestinal peptide (VIP)-positive) interneurons
12
,
13
, activity is essential before postnatal day 3 for correct migration, and that after postnatal day 3, glutamate-mediated activity controls the development of their axons and dendrites. Furthermore, we show that the engulfment and cell motility 1 gene (
Elmo1
)
14
, a target of the transcription factor distal-less homeobox 1 (
Dlx1
)
15
, is selectively expressed in Re
+
and Cr
+
interneurons and is both necessary and sufficient for activity-dependent interneuron migration. Our findings reveal a selective requirement for activity in shaping the cortical integration of specific neuronal subtypes.
Journal Article
Freddy's teddy
Little Teddy has a rip, but Freddy's mother has needle, thread, and more than enough stuffing to fix him.
Book
The Use of Poly(N-vinyl pyrrolidone) in the Delivery of Drugs: A Review
Polyvinylpyrrolidone (PVP) is a hydrophilic polymer widely employed as a carrier in the pharmaceutical, biomedical, and nutraceutical fields. Up to now, several PVP-based systems have been developed to deliver different active principles, of both natural and synthetic origin. Various formulations and morphologies have been proposed using PVP, including microparticles and nanoparticles, fibers, hydrogels, tablets, and films. Its versatility and peculiar properties make PVP one of the most suitable and promising polymers for the development of new pharmaceutical forms. This review highlights the role of PVP in drug delivery, focusing on the different morphologies proposed for different polymer/active compound formulations. It also provides detailed information on active principles and used technologies, optimized process parameters, advantages, disadvantages, and final applications.
Journal Article
Artificial Intelligence-Based Digital Transformation for Sustainable Societies: The Prevailing Effect of COVID-19 Crises
Digital transformation (DT) is becoming a necessity for enterprises in different industries all over the world. The necessity for DT turned out to be inevitable with the coronavirus (COVID-19) outbreak. On March 2020, the World Health Organization (WHO) announced the COIVD-19 as global pandemic that caused thousands of deaths and brought the world to a standstill with huge economic burden (World Health Organization, 2020). This pandemic accelerated the need for organizations to transform using extensive digitization in response to the unprecedented change (Morgan, 2020). However, significant obstacles still encounter these organizations when it comes to recommending the necessary changes to make the digital leap. In today’s artificial intelligence age, digital transformation has enormous impact across societies (Nambisan, 2019; George & Paul, 2020; Majchrzak, Markus, Wareham, 2016); organizations need to realize that both digital transformation and artificial intelligence have to go hand in hand to help achieve prosperous digital transformation (Wuest et al., 2020). Therefore, becoming a digital enterprise is much more than investing in latest digital technologies. It is about adopting artificial intelligence to support the business strategy (Joda et al. 2020), searching for new business models (Kotarba, 2018), and considering afresh how to embed the social impact in the measure of the success of the business.
Journal Article
رحلات ماركو بولو
من أعماق الغابات والصحراوات والجبال والوديان .. من وسط الشعوب وأعيادهم وعاداتهم .. من فوق لغات عديدة وثقافات مختلفة دائما تأتينا كتب أدب الرحلات، فهى دائما كتب تجوب العالم شرقه وغربه .. تجتمع حبات در ثقافاته فى كتاب واحد، وهو ما جعل لها مذاق خاص وأدب خاص يمتعنا وفى ذات الوقت يطلعنا على كل جديد لم نألفه ولم نعايشه فى بلادنا أيا كانت هذه البلاد. ومن كتب أدب الرحلات الذائعة الصيت والهامة فى ذات الوقت رحلات \"ماركوبولو\" ذلك الرحالة الذى تعد رحلاته مرجعا هاما فيما يتعلق بحضارات آسيا القديمة وشعوبها، فهى رحلات جابت البلاد من إيطاليا للصين مرورا بآسيا وحضاراتها الجذابة مخلفة ورائها صفحات غنية ثرية نافذة فى نظرتها ونافذة يطل منها العالم إلى تلك الحضارات البائدة. ففى هذه الرحلات ومجلداتها الثلاثة قام \"ماركوبولو\" بتسجيل نواحى الحياة العديدة فى هذه البلاد من عادات لسكانها وما اتبعه حكامها فى إدارتها، أيضا وصفها وصفا تفصيليا سواء كان هذا الوصف لطبيعتها الجغرافية أو الإقتصادية أو السياسية أو الإجتماعية. فهو كتاب يقرأه قارئ عادى وقارئ متخصص وباحث فى التاريخ على السواء .. فهو للصغير ممتع وللكبير مرجع، وفى المكتبة الأدبية درة والمكتبة التاريخية تحفة، وهو ما يجعلنا لا نتعجب إذ جاءنا كحلقة من سلسلة \"الأعمال الخاصة\" فهو عمل خاص ذو مذاق متميز متفرد.
Book
Ultrafast 2D IR spectroscopy of the excess proton in liquid water
Despite decades of study, the structures adopted to accommodate an excess proton in water and the mechanism by which they interconvert remain elusive. We used ultrafast two-dimensional infrared (2D IR) spectroscopy to investigate protons in aqueous hydrochloric acid solutions. By exciting O–H stretching vibrations and detecting the spectral response throughout the mid-IR region, we observed the interaction between the stretching and bending vibrations characteristic of the flanking waters of the Zundel complex, [H(H2O)2]+, at 3200 and 1760 cm–1, respectively. From time-dependent shifts of the stretch-bend cross peak, we determined a lower limit on the lifetime of this complex of 480 femtoseconds. These results suggest a key role for the Zundel complex in aqueous proton transfer.
Journal Article