Do changes in coiling directions in planktonic foraminifera correspond to dimorphic reproduction?

A total of 25 surface sediment samples, collected along a North-South transect (from 9.69° N to 55.01° S and from 80° E and 40° E) in the south western Indian Ocean, were used to study the coiling direction patterns in foraminifera planktonic species Neogloboquadrina pachyderma, Globigerinita glutinata and Globigerina bulloides. Comparison between the coiling direction and mean proloculus size (MPS) revealed that all these profiles along N-S transect were not in tandem and thus indicated non-existence of any relationship between the coiling direction and reproductive modes expressed in terms of mean proloculus size.     

Strain estimation from single forms of distorted fossils — A computer graphics and MATLAB approach

Most of the existing methods of strain analysis can estimate strain in a single form of distorted brachiopod, or trilobite provided independent evidence, such as the association of the fossil with cleavage and/or stretching lineation is available for inferring the direction of maximum principal strain. This article proposes a simple computer graphics based method and its MATLAB code that determine the minimum amount of strain in a single distorted fossil form even if data for inferring the maximum principal strain direction are lacking. Our method is a rapid computer-graphics alternative to some of the existing analytical methods. In a distorted fossil form of original bilateral symmetry, the relative senses of angular shears along the hinge line and the median line are mutually opposite to each other. It follows, therefore, that the maximum principal strain direction lies within the acute angle between the hinge and the median lines in the plane of the fossil. Using this principle, our method performs several simulations such that each simulation retrodeforms the distorted fossil by assuming a particular orientation, lying within the acute angle between the hinge line and the median line, as the potential direction of the maximum principal strain. Each simulation of retrodeformation yields a potential strain ratio. The distribution of all the potential strain ratios, obtained by assuming different orientations as the potential directions of the maximum strain, is typically a parabola-like curve with a distinct vertex that corresponds to the minimum amount of strain in the distorted fossil. An entirely computer graphical approach is somewhat time-intensive because it involves a large number of retrodeformational simulations. We, therefore, give a MATLAB code, namely, the Minstrain, that rapidly retrodeforms the fossil and determines the minimum strain with precision.     

Redox-linked conformation change and electron transfer between monoheme c-type cytochromes and oxides

Electron transfer between redox active proteins and mineral oxides is important in a variety of natural as well as technological processes, including electron transfer from dissimilatory metal-reducing bacteria to minerals. One of the pathways that could trigger electron transfer between proteins and minerals is redox-linked conformation change. We present electrochemical evidence that mitochondrial cytochrome c (Mcc) undergoes significant conformation change upon interaction with hematite and indium-tin oxide (ITO) surfaces. The apparent adsorption-induced conformation change causes the protein to become more reducing, which makes it able to transfer electrons to the hematite conduction band. Although Mcc is not a protein thought to be involved in interaction with mineral surfaces, it shares (or can be conformed so as to share) some characteristics with multiheme outer-membrane cytochromes thought to be involved in the transfer of electrons from dissimilatory iron-reducing bacteria to ferric minerals during respiration. We present evidence that a 10.1 kDa monohoeme cytochrome isolated and purified from Acidiphilium cryptum, with properties similar to those of Mcc, also undergoes conformation change as a result of interaction with hematite surfaces.     

Assessing anthropogenic pressure and its impact on Hippophae salicifolia pockets in Central Himalaya, Uttarakhand

Natural habitat of Hippophae salicifolia in Central Himalaya is continuously being degraded due to habitat destruction and harvesting.Although logging is prohibited,habitat destruction has increased because of regular road construction,repairing and broadening activities.In addition,Hippophae resources are continuously being harvested by lopping(both partial and complete) for fuelwood,fodder and fruits in higher Himalayan region.This paper presents a detailed analysis of relationship between density,demographic structure,and harvesting of H.salicifolia growing pockets in the five major valleys(Gangotri,Yamunotri,Niti,Mana and Bhyundhar) of Uttarakhand in Central Himalaya,India.A total of 120 quadrats were laid randomly to study population structure,regeneration,sex ratio and lopping using quadrats of 100 m 2(24 in each valley) in Hippophae growing patches.Our study shows that the density,size distribution,and regeneration of Hippophae vary considerably among the major valleys.Trees in the Yamunotri valley have the highest density of large trees but the lowest density of seedlings.In contrast,there are few large trees but many seedlings in the Mana valley.The number and size of lopped trees also varied among the valleys.Lopping was greatest in Bhyundhar(11.4%) and Yamunotri(19.7%) and least in Niti(3.9%).The size of lopped trees differed substantially as well.In Bhyundhar,the largest trees were taken while saplings were taken in Yamunotri.Our study revealed that unsustainable harvesting from plants for fuel,fencing and fruits along with road broadening activities in Central Himalaya are the main cause of habitat destruction.Our research highlights the urgent need for in-situ and ex-situ conservation of Hippophae salicifolia so that it’s potential can be harnessed sustainably by rural hill societies for their socio-economic development.     

Experimental impact shock chemistry on planetary icy satellites

We present new experimental results on impact shock chemistry into icy satellites of the outer planets. Icy mixtures of pure water ice with CO₂, Na₂CO₃, CH₃OH, and CH₃OH/(NH₄)₂SO₄ at 77 K were ablated with a powerful pulsed laser—a new technique used to simulate shock processes which can occur during impacts. New products were identified by GC-MS and FTIR analyses after laser ablation. Our results show that hydrogen peroxide is formed in irradiated H₂O/CO₂ ices with a final concentration of 0.23%. CO and CH₃OH were also detected as main products. The laser ablation of frozen H₂O/Na₂CO₃ generates only CO and CO₂ as destruction products from the salt. Pulsed irradiation of water ice containing methanol leads also to the formation of CO and CO₂, generates methane and more complex molecules containing carbonyl groups like acetaldehyde, acetone, methyl formate, and a diether, dimethyl formal. The last three compounds are also produced when adding ammonium sulfate to H₂O/CH₃OH ice, but acetone is more abundant. The formation of two hydrocarbons, CH₄ and C₂H₆ is observed as well as the production of three nitrogen compounds, nitrous oxide, hydrogen cyanide, and acetonitrile.     

A comprehensive and quantitative assessment of Raunthi Gad flash flood,Rishi Ganga catchment,central Himalaya,Uttarakhand, India

Natural Hazards - Drought severity is increasing in Southern Africa which is affecting rain-fed agriculture, the main source of livelihood in most countries in this region. The study assessed the...     

Appropriate viscous damping for nonlinear time‐history analysis of base‐isolated reinforced concrete buildings

There is no consensus at the present time regarding an appropriate approach to model viscous damping in nonlinear time‐history analysis of base‐isolated buildings because of uncertainties associated with quantification of energy dissipation. Therefore, in this study, the effects of modeling viscous damping on the response of base‐isolated reinforced concrete buildings subjected to earthquake ground motions are investigated. The test results of a reduced‐scale three‐story building previously tested on a shaking table are compared with three‐dimensional finite element simulation results. The study is primarily focused on nonlinear direct‐integration time‐history analysis, where many different approaches of modeling viscous damping, developed within the framework of Rayleigh damping are considered. Nonlinear direct‐integration time‐history analysis results reveal that the damping ratio as well as the approach used to model damping has significant effects on the response, and quite importantly, a damping ratio of 1% is more appropriate in simulating the response than a damping ratio of 5%. It is shown that stiffness‐proportional damping, where the coefficient multiplying the stiffness matrix is calculated from the frequency of the base‐isolated building with the post‐elastic stiffness of the isolation system, provides reasonable estimates of the peak response indicators, in addition to being able to capture the frequency content of the response very well. Furthermore, nonlinear modal time‐history analyses using constant as well as frequency‐dependent modal damping are also performed for comparison purposes. It was found that for nonlinear modal time‐history analysis, frequency‐dependent damping, where zero damping is assigned to the frequencies below the fundamental frequency of the superstructure for a fixed‐base condition and 5% damping is assigned to all other frequencies, is more appropriate, than 5% constant damping. Copyright © 2013 John Wiley & Sons, Ltd.     

Dry season precipitation over the Mesoamerican Biological Corridor is more sensitive to deforestation than to greenhouse gas driven climate change

To prevent the loss of biodiversity in northern Central America, which is one of 34 global biodiversity hotspots, the Mesoamerican Biological Corridor, a network of protected parks and reserves has been proposed. While on-going deforestation to croplands and pastures outside the protected regions is likely to effect the dry season precipitation over the regenerated and extant forests in the proposed protected regions, global climate change driven precipitation changes may also be a significant factor, at least at some locations. This study compares the effects of land cover change to the effects of elevated greenhouse gas concentrations on precipitation in the proposed areas of the Mesoamerican Biological Corridor network. Using 5 consecutive dry season simulations of the effects of land cover change that included dry, wet and normal years, and using statistically downscaled global climate model (GCM) precipitation from the fourth assessment report (AR4), a larger expanse of the proposed protected regions was found more sensitive to precipitation decreases due to land cover changes. Two specific protected regions however stand out: the Maya Highlands and some areas of the Maya lowlands that were more sensitive to global climate change driven precipitation decreases. In these protected regions it is likely that irrespective of local policies the climate change signal would dominate.