Agriculture on the Brazilian basaltic plateau. Cultivation practices and soil conservation : First results of the Potiribu project

In the Northwest Vietnam, traditional maize (Zea mays) cultivation practices of farmers mainly based on sole cropping, intensive tillage combined with burning crop residues on steep slopes. These cultivation practices resulted in severe erosion, soil degradation, reducing crop production and un-sustainable production systems. It requires assessing of the impact of agroforestry practice on the soil conservation in the context of the upland areas in Northwest Vietnam. This study has been carried out since 2017 to present the actual impact of agroforestry practice including longan (Dimocarpus longan)+mango (Mangifera indica L.)+maize+forage grass strips (Guinea-Panicum maximum) on soil conservation. The assessment based on quantifying soil loss by soil traps and evaluating terrace’s formation by erosion pins placing above forage grass strips. The sole maize system had been using for the comparison. The initial results showed that the evaluated agroforestry practice reduced soil loss from 18.3 to 37.4% in compared with the sole maize system in 2017 and 2018, respectively. In the second year (2018), the deposition of sediment on the front and rear pins at the above grass trips was 0.81 and 0.41 cm, respectively. It indicated the increment in soil surface at the above grass strips. In contrast, the negative value of the deposition of sediment was recorded in the sole maize system. We are continuing to monitor the impact of agroforestry practices on reducing soil loss and terrace formation, and evaluate the function of the system on soil fertility improvement, nutrient use efficiency and economic profitability.

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Discussion of the Oblique Rotator Model Cases Of 108 Aqr and x Serp.

International Astronomical Union Colloquium ◽

10.1017/s0252921100080891 ◽

1976 ◽

Vol 32 ◽

pp. 577-588

Author(s):

C. Mégessier ◽

V. Khokhlova ◽

T. Ryabchikova

Keyword(s):

Mathematical Formulation ◽

The Other ◽

Rotator Model ◽

Oblique Rotator ◽

First Results

My talk will be on the oblique rotator model which was first proposed by Stibbs (1950), and since received success and further developments. I shall present two different attempts at describing a star according to this model and the first results obtained in the framework of a Russian-French collaboration in order to test the precision of the two methods. The aim is to give the best possible representation of the element distributions on the Ap stellar surfaces. The first method is the mathematical formulation proposed by Deutsch (1958-1970) and applied by Deutsch (1958) to HD 125248, by Pyper (1969) to α2CVn and by Mégessier (1975) to 108 Aqr. The other one was proposed by Khokhlova (1974) and used by her group.

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Meridional Circulation, Turbulence, and Diffusion Processes in Stars

International Astronomical Union Colloquium ◽

10.1017/s0252921100080477 ◽

1976 ◽

Vol 32 ◽

pp. 109-116 ◽

Cited By ~ 1

Author(s):

S. Vauclair

Keyword(s):

Convection Zone ◽

Diffusion Processes ◽

Meridional Circulation ◽

Diffusion Time ◽

Work In Progress ◽

First Results ◽

Stellar Envelopes ◽

And Diffusion ◽

Turbulence And Diffusion ◽

Hr Diagram

This paper gives the first results of a work in progress, in collaboration with G. Michaud and G. Vauclair. It is a first attempt to compute the effects of meridional circulation and turbulence on diffusion processes in stellar envelopes. Computations have been made for a 2 Mʘstar, which lies in the Am - δ Scuti region of the HR diagram.Let us recall that in Am stars diffusion cannot occur between the two outer convection zones, contrary to what was assumed by Watson (1970, 1971) and Smith (1971), since they are linked by overshooting (Latour, 1972; Toomre et al., 1975). But diffusion may occur at the bottom of the second convection zone. According to Vauclair et al. (1974), the second convection zone, due to He II ionization, disappears after a time equal to the helium diffusion time, and then diffusion may happen at the bottom of the first convection zone, so that the arguments by Watson and Smith are preserved.

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Investigation of cluster layers of small netal particles by TEM, SEM, EELS and by photoacoustic spectroscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100174382 ◽

1990 ◽

Vol 48 (4) ◽

pp. 250-251

Author(s):

H. Seiler ◽

U. Haas ◽

K.H. Körtje

Keyword(s):

Bulk Material ◽

High Vacuum ◽

Optical Methods ◽

Metal Particles ◽

Silver Particles ◽

Low Loss ◽

Plasmon Excitation ◽

First Results ◽

Diffraction Patterns ◽

Small Metal Particles

The physical properties of small metal particles reveal an intermediate position between atomic and bulk material. Especially Ag has shown pronounced size effects. We compared silver layers evaporated in high vacuum with cluster layers of small silver particles, evaporated in N2 at a pressure of about 102 Pa. The investigations were performed by electron optical methods (TEM, SEM, EELS) and by Photoacoustic (PA) Spectroscopy (gas-microphone detection).The observation of cluster layers with TEM and high resolution SEM show small silver particles with diameters of about 50 nm (Fig. 1 and Figure 2, respectively). The electron diffraction patterns of homogeneous Ag layers and of cluster layers are similar, whereas the low loss EELS spectra due to plasmon excitation are quite different. Fig. 3 and Figure 4 show first results of EELS spectra of a cluster layer of small silver particles on carbon foil and of a homogeneous Ag layer, respectively.

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Towards 1-Ångstrom-resolution STEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100150812 ◽

1993 ◽

Vol 51 ◽

pp. 996-997

Author(s):

H.S. von Harrach ◽

D.E. Jesson ◽

S.J. Pennycook

Keyword(s):

High Resolution ◽

Field Emission ◽

Phase Contrast ◽

Spherical Aberration ◽

A Priori ◽

Dark Field ◽

Image Resolution ◽

Objective Lens ◽

Annular Dark Field ◽

First Results

Phase contrast TEM has been the leading technique for high resolution imaging of materials for many years, whilst STEM has been the principal method for high-resolution microanalysis. However, it was demonstrated many years ago that low angle dark-field STEM imaging is a priori capable of almost 50% higher point resolution than coherent bright-field imaging (i.e. phase contrast TEM or STEM). This advantage was not exploited until Pennycook developed the high-angle annular dark-field (ADF) technique which can provide an incoherent image showing both high image resolution and atomic number contrast.This paper describes the design and first results of a 300kV field-emission STEM (VG Microscopes HB603U) which has improved ADF STEM image resolution towards the 1 angstrom target. The instrument uses a cold field-emission gun, generating a 300 kV beam of up to 1 μA from an 11-stage accelerator. The beam is focussed on to the specimen by two condensers and a condenser-objective lens with a spherical aberration coefficient of 1.0 mm.

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Imaging of polymer single crystals in low-voltage, high-resolution scanning electron microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100178665 ◽

1990 ◽

Vol 48 (4) ◽

pp. 1106-1107

Author(s):

W.W. Adams ◽

G. Price ◽

A. Krause

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

High Resolution ◽

Single Crystals ◽

Low Voltage ◽

Polymer Surface ◽

Beam Current ◽

Image Features ◽

First Results ◽

Scanning Electron

It has been shown that there are numerous advantages in imaging both coated and uncoated polymers in scanning electron microscopy (SEM) at low voltages (LV) from 0.5 to 2.0 keV compared to imaging at conventional voltages of 10 to 20 keV. The disadvantages of LVSEM of degraded resolution and decreased beam current have been overcome with the new generation of field emission gun SEMs. In imaging metal coated polymers in LVSEM beam damage is reduced, contrast is improved, and charging from irregularly shaped features (which may be unevenly coated) is reduced or eliminated. Imaging uncoated polymers in LVSEM allows direct observation of the surface with little or no charging and with no alterations of surface features from the metal coating process required for higher voltage imaging. This is particularly important for high resolution (HR) studies of polymers where it is desired to image features 1 to 10 nm in size. Metal sputter coating techniques produce a 10 - 20 nm film that has its own texture which can obscure topographical features of the original polymer surface. In examining thin, uncoated insulating samples on a conducting substrate at low voltages the effect of sample-beam interactions on image formation and resolution will differ significantly from the effect at higher accelerating voltages. We discuss here sample-beam interactions in single crystals on conducting substrates at low voltages and also present the first results on HRSEM of single crystal morphologies which show some of these effects.

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Melting driven by natural convection A comparison exercise: first results

Revue Générale de Thermique ◽

10.1016/s0035-3159(99)88013-1 ◽

1999 ◽

Vol 38 (1) ◽

pp. 5-26

Author(s):

O Bertrand

Keyword(s):

Natural Convection ◽

First Results ◽

Comparison Exercise

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Multidisciplinary management of vascular access for haemodialysis: from the preparation of the initial access to the treatment of stenosis and thrombosis

VASA ◽

10.1024/0301-1526/a000093 ◽

2011 ◽

Vol 40 (3) ◽

pp. 188-198 ◽

Cited By ~ 19

Author(s):

Reinhold ◽

Haage ◽

Hollenbeck ◽

Mickley ◽

Ranft

Keyword(s):

Vascular Access ◽

Central Venous ◽

Advantages And Disadvantages ◽

Multidisciplinary Study ◽

First Results ◽

Lower Complication ◽

Lower Complication Rate ◽

Access Problems ◽

Arteriovenous Grafts ◽

The Individual

In February 2008 a multidisciplinary study group was established in Germany to improve the treatment of patients with potential vascular access problems. As one of the first results of their work interdisciplinary recommendations for the management of vascular access were provided, from the creation of the initial access to the treatment of complications. As a rule the wrist arteriovenous fistula (AVF) is the access of choice due to its lower complication rate when compared to other types of access. The AVF should be created 3 months prior to the expected start of haemodialysis to allow for sufficient maturation. Second and third choice accesses are arteriovenous grafts (AVG) and central venous catheters (CVC). Ultrasound is a reliable tool for vessel selection before access creation, and also for the diagnosis of complications in AVF and grafts. Access stenosis and thrombosis can be treated surgically and interventionally. The comparison of both methods reveals advantages and disadvantages for each. The therapeutic decision should be based on the individual patients constitution, and also on the availability and experience of the involved specialists.

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