text:
\section{Introduction}

The dynamics and roughening of moving interfaces in a disordered
medium is a subject of intense interest in non-equilibrium
statistical physics \cite{barabasi95}. Examples where such processes
are relevant include thin film deposition \cite{mg00}, slow
combustion fronts in paper \cite{Myllys00}, fluid invasion in
fractals \cite{asikainen02} and porous media
\cite{bg90,sch57,krug97}, and wetting and propagation of contact
lines \cite{mrkr,jr90,ek94}. The understanding of the underlying
physics involved in interface roughening is crucial to the control
and optimization of these processes, with immediately apparent
technological importance. Progress in the theoretical study of
interface dynamics has been made over the last two decades and a
number of theories have been developed \cite{barabasi95,krug97}
which agree with the experimental findings in some cases. Much of
the theoretical work has been based on analyzing (spatially) local
interface equations, such as the celebrated Kardar-Paris-Zhang (KPZ)
equation \cite{kpz}, where the physics is governed by a (nonlinear) partial
differential equation which couples the interface {\it locally} with
itself and the quenched randomness. However, in many cases such a
description is not possible \cite{asikainen02,dubeprl}.

A particularly important class of problems in the field of kinetic
roughening where local theories cannot provide a complete
description are those involving fluid invasion in porous media,
which are often experimentally studied using Hele-Shaw cells
\cite{SOH1,soh,Hernandez-machado01,GMH02} or even paper as the wetting medium
\cite{bb92,hs95,amaral94,KHO96}. The reason for this is that if the
transport of liquid to the advancing wetting front from the
reservoir is neglected as in local theories, slowing down of the
front in spontaneous imbibition of water in paper cannot be
explained by local theories unless the liquid conservation law is
included in some artificial way. To properly describe the dynamics
of wetting fronts in random medium is a challenging task, and there
are several recent theoretical attempts to this end
\cite{Hernandez-machado01,pc03,ganesan98}. In particular, in Refs.
\cite{dubeprl,dube00a,dube01,AME04} Dube {\it et al.} developed a
phase-field model explicitly addressing the issue of liquid
conservation in the wetting of a random medium. This is achieved by
a generalized Cahn-Hilliard equation with suitable boundary
condition which couples the system to the reservoir. A variant of
the sharp interface projection method \cite{kawasaki82,elder01} was used to
analytically obtain a non-local interface equation for the case of
spontaneous imbibition, and from it a new time dependent length scale governing the
kinetic roughening $\xi_\times \sim t^{1/4}$, was extracted. In
Refs. \cite{dubeprl,dube01} the kinetic roughening of 2D wetting
fronts was also analyzed, and estimates for the corresponding
scaling exponents were obtained. Furthermore, in a recent
comprehensive review paper \cite{alava04} the case of forced wetting
in 2D was briefly discussed, and in Ref. \cite{dube05} forced
wetting in a 3D model of paper was also considered.

In the present work our aim is to carry out a comprehensive analysis
of wetting fronts in 2D in the case of forced wetting. To this end,
we use the phase-field model of Ref. \cite{dubeprl} with boundary
conditions corresponding to a constant mass flux at the reservoir
boundary. This makes the wetting fronts move at a constant average
velocity, in contrast to the Washburn law for spontaneous wetting.
We first expand on the standard projection method to make it usable
under constant flow boundary conditions, and derive the linearized
interface equations corresponding to the forced case. Analysis of
these equations reveals a crossover length scale $\xi_\times$, which
is time-independent in contrast to the spontaneous wetting case
\cite{dubeprl}, and depends on the interface velocity as
$\xi_\times \propto v^{-1/2}$. It separates two
regimes of dissipative behavior and governs the kinetic roughening
of the interfaces by giving an upper cutoff for the correlation
length of the interface fluctuations. By numerically integrating the
phase field model, we find that the interfaces are superrough with a
roughness exponent of $\chi = 1.35 \pm 0.05$, and a growth exponent
of $\beta = 0.50 \pm 0.02$. These results are in good agreement with
recent experiments on Hele-Shaw cells \cite{soh}. We also make a direct
numerical comparison between the solutions of the full phase field
model and the corresponding linearized interface equation. Good
agreement is found in spatial correlations, while the temporal
correlations in the two models are somewhat different.

This paper proceeds as follows: In Section \ref{model} we define the
phase field model, and present results from the projection and
linearization procedure. We present the resulting interface
equations, as well as discuss how the crossover length scale
$\xi_\times$ emerges. In Section \ref{numerics} we present our
numerical results for the driven interfaces in disordered medium. We
consider both spatial and temporal correlation functions, as well as
compare the numerical results from the linearized interface equation
to the phase field model. Finally, we present our discussion and
conclusions in Section \ref{conclusions}. The Appendices A and B
contain some technical details on the projection and linearization
procedures leading to the interface equations.

\section{Model for Wetting}
\label{model}

\subsection{Definition of the Phase Field Model}

The model describes the dynamics of a liquid invading a disordered
medium at a coarse-grained level. A phase field is used to
describe the ``wet'' and ``dry'' phases, with a free energy
functional such that the dimensionless phase field obtains the
values $\phi=+1$ and $\phi=-1$ at the wet and dry phases,
respectively. Since the phase field is an effective density field
it is locally conserved. Energy cost for an interface is added by
the standard coarse-grained gradient squared term. The interaction
energy between the random medium and the invading liquid is
represented by a quenched random field linearly coupled to the
phase field. This leads to the free energy density \cite{dubeprl}
\begin{equation}
\label{free energy}
\mathcal{F}[\phi(\mathbf{x},t)]=\frac{1}{2}(\nabla\phi(\mathbf{x,t}))^2+V(\phi(\mathbf{x,t}))
-\alpha(\mathbf{x})\phi(\mathbf{x},t),
\end{equation}
where $V$ has two minima at $\phi=-1$ and $\phi=+1$, and $\alpha$ is the
quenched random field. The standard Ginzburg-Landau form is chosen for $V$,
{\it i.e.} $V(\phi)=-\phi^2/2+\phi^4/4$ \cite{dubeprl}, and the quenched
field obeys the relations
\begin{eqnarray}
\label{random field}
\langle\alpha(\mathbf{x})\rangle&=&0\\
\langle\alpha(\mathbf{x})\alpha(\mathbf{x}')\rangle&=&(\Delta \alpha)^2
\delta(\mathbf{x}-\mathbf{x}').
\end{eqnarray}
The case of positive (negative) $\langle\alpha(\mathbf{x})\rangle$
corresponds to the liquid spontaneously wetting (dewetting) the
medium for the case of no external driving \cite{dubeprl}.

The equation of motion for the conserved phase field is given by
the continuity equation $\partial_t\phi=-\nabla\cdot \mathbf{j}$
and Fick's law $\mathbf{j}=-\nabla\mu$, where
$\mu=\delta\cal{F}/\delta\phi$. The result is
\begin{equation}
\label{pf_eq}
\partial_t \phi({\bf x},t) = \nabla^2 \mu({\bf x},t) = \nabla^2 \left[
- \phi({\bf x},t) + \phi^3({\bf x},t) - \nabla^2 \phi({\bf x},t) -
\alpha({\bf x})\right],
\end{equation}
which is essentially the Cahn-Hilliard equation \cite{cahn58}. Note
that dimensionless units have been set such that the constant
relating the phase field gradient to the free energy and the
mobility in Fick's law are both unity. This fixes the choice of
units in Eq. \eqref{pf_eq}.

In Refs. \cite{dubeprl,dube00a} the case of spontanous,
capillary driven wetting was modeled with Eq. \eqref{pf_eq} using
boundary conditions where the chemical potential was set to a
constant at the liquid reservoir $y=0$. In order to model the
experimental setup of driving the liquid from the reservoir, we
define our phase-field in the half-plane $\{\mathbf{x}\vert y\ge
0\}$, and at the line $y=0$ impose the boundary condition
$\nabla\mu = -F\hat{y}$, where $\hat{y}$ is the unit vector, and
$F$ is a constant (flux) parameter (see Fig. 1(a)). On the top end
of the system we set $\phi(y\rightarrow\infty)=-1$, and use
periodic boundaries in the $x$ direction. Physically this
corresponds to driving the liquid via a constant mass flow,
leading to an interface propagating at a constant average velocity
\cite{alava04}.

The initial condition for the phase field is given by a step
function at some height $H(0)=H(t=0)$,
$\phi(\mathbf{x},t=0)=1-2\Theta(y-H(0))$. $H(0)$ is also a
parameter in our model, but with the gradient boundary condition
here its value is irrelevant, in contrast to the case of
spontaneous imbibition, where $H(0)$ defines the initial average
velocity of the interface \cite{dubeprl}.

\subsection{Linearized interface equation}

The quenched disorder field $\alpha(\mathbf{x})$ will cause an
initially flat interface to kinetically roughen when it propagates
as the liquid invades the medium. A key step in understanding the
physics of this process is writing an equation of motion for the
1D single-valued height variable $H(x,t)$, defined conveniently by
the condition $\phi(x,H(x,t))=0$ as shown in Fig. 1(a). It is not
obvious {\it a priori} that this can be done, since the problem is
inherently non-local due to the conservation law \cite{dubeprl},
but it has been shown in Refs. \cite{dubeprl} that this
can be done using methods discussed in Refs.
\cite{kawasaki82,bray94,langer77}. In Appendix \ref{A} we will
discuss some technical details of the derivation. The main idea is
to use the relevant Green's function of the problem defined by
\begin{equation}
\nabla^2  G(x,y|x',y') = \delta (x-x') \; \delta(y-y'),
\end{equation}
with appropriate boundary conditions. This leads to the
integro-differential equation of motion
\begin{equation}
2\int_{-\infty}^{\infty} dx' \; G (x,H(x,t)|x',H(x',t)) \;
\frac{\partial H(x',t)}{\partial t} = \alpha (x,H(x,t)) + \sigma \kappa
+\Lambda\vert_{y=H(x,t)},
\label{non-local}
\end{equation}
where $\kappa$ is the interface curvature, and $\Lambda$ is the
boundary term, which is non-vanishing for inhomogenous boundary
conditions. Note that Eq.~\eqref{non-local} holds for any geometry
given the appropriate Green's function. For the half plane with
von Neumann boundary condition at $y=0$, the 2D Green's function
is obtained by image charge method as
\begin{equation}
\label{half-plane Green}
G(x,y|x',y') = \frac{1}{4\pi} \ln\left[((x-x')^2 +
(y-y')^2)((x-x')^2+(y+y')^2)\right].
\end{equation}
The next step towards an explicit interface equation is to
linearize in fluctuations around the disorder-free system
solution, $H(x,t)=H_0(t)+h(x,t)$, and transform to Fourier space,
where the equations of different modes of fluctuation are
decoupled. The half plane Green's function defined in Eq.
(\ref{half-plane Green}) is not square integratable, however, and
thus it does not have a Fourier representation. However, we have
found that we can avoid this problem by considering a finite strip
of width $L$ where $0 \le x \le L$, and derive a linearized
equation of motion for the {\it discrete} Fourier modes of the
fluctuations. Then we can take the limit $L \rightarrow \infty$ to
obtain the equation of motion in Fourier space for an interface in
half-plane geometry, and the end result is well-defined. This
procedure is exposed in some detail in Appendix \ref{B}.

The linearization procedure, by construction, gives a separate
equation of motion for the mean interface position $H_0(t)$, which
turns out to be coupled to all the fluctuation Fourier modes
$h_k$, while the evolutions of the fluctuation modes are
independent of each other. The resulting equations are given by
\begin{eqnarray}
\label{ave_int}
\dot{H_0}&=&\frac{F}{2}; \\
\label{fluct_int}
\dot{h}_k \left( 1 + e^{-2 \vert k \vert H_0} \right)&=&
|k| \left( -\dot H_0 \; h_k \left( 1 - e^{-2 \vert k \vert H_0}
\right) - \sigma k^2 h_k + \eta_k (t) \right),
\end{eqnarray}
from which we immediately obtain the expected result that
\begin{equation}
\label{linear}
 H_0(t) = \frac{Ft}{2}.
\end{equation}
This should be contrasted with the Washburn law $H_0(t) \propto
t^{1/2}$ in the case of spontaneous wetting \cite{dubeprl}. It is
interesting to note that the functional form of Eq.
\eqref{fluct_int} for the fluctuations of the interface is similar
to the case of spontaneous wetting in Ref. \cite{dubeprl}, except
for some sign changes in the terms. It can be shown that these
changes are a direct consequence of the differences between the
Green's functions in the two cases, and they lead to significant
differences in the behavior of the fluctuations as will be
discussed below.

The most immediate aspect of these equations is that the
fluctuation equation is non-local in real space. This is to be
expected due to the conservation law \cite{dubeprl}. The locality
of the interface equation in Fourier space owes to the fact that
it has been linearized. The interface configuration couples to the
disorder in a fundamentally non-linear manner, a fact that is
somewhat obscured by the superficially simple form of the disorder
term $\eta_k$, which is defined as
\begin{equation}
 \eta_k (t) \equiv \int dx~e^{-ikx} \alpha(x,H(x,t))
\end{equation}
The moments of $\eta_k$ averaged over disorder realizations thus
couple to the interface configuration realizations, which in turn
are defined by the disorder. This makes the analysis of $\eta_k$ a
formidable task that must be solved self-consistently involving
the interface equation. In more explicit terms, in expressions
such as $\langle \alpha(x,H(x,t))\alpha(x',H(x',t'))\rangle$, the
angular brackets denote averages over different realizations of
$H$, and results can only be obtained numerically.

In Eq. \eqref{fluct_int} there are two terms that dissipate
fluctuations corresponding to different physical effects: the
surface tension term $\sigma k^3 h_k$ and the liquid transport
(conservation law) $|k| \dot H_0 \left( 1 - e^{-2 \vert k \vert
H_0}\right) h_k$. The surface tension dominates when
$k\dot{H_0}\ll \sigma k^3$, leading to a {\it time independent} crossover length
scale between the two terms given by
\begin{equation}
\label{cross}
\xi_\times=2\pi\sqrt{\frac{\sigma}{\dot{H}_0}}=2\pi\sqrt{\frac{2\sigma}{F}}.
\end{equation}
This is in striking contrast to the spontaneous case, where the
corresponding crossover length is {\it time dependent} with
$\xi_\times \propto t^{1/4}$ \cite{dubeprl}. Moreover, in the
dispersion relation of the fluctuations there is an additional
crossover in the transport term obtained by comparing the length
scales $H_0(t)$ and $k$. Namely, for $kH_0(t)\gg 1$ the transport
term is $k\dot{H}_0$, while for $kH_0(t)\ll 1$ it is
$2k^2H_0\dot{H}_0$, leading to a crossover between $\omega\propto
k$ and $\omega\propto k^2$ in the dispersion relation of the
interface fluctuations. Regardless of the magnitude of $kH_0(t)$,
we will show through numerical studies that the crossover length
scale $\xi_\times$ controls the kinetic roughening of the
interface in analogy to the spontaneous imbibition case, in that
it defines an upper cut-off for fluctuations that are increasing
in time and correlated by the surface tension.

\section{Numerical analysis}
\label{numerics}

\begin{figure}[t]

\includegraphics [height = 6cm, width = 6cm]{SetupDriven.eps}
\includegraphics [height = 6cm, width = 6cm]{MuProfile.eps}
\includegraphics [height = 6cm, width = 6cm]{PhiProfile.eps}
\includegraphics [height = 6cm, width = 6cm]{every8th.eps}
\caption{
(a) A schematic geometry and setup of the model. The
height of the front is described by a single-valued function
$H(x,t)$, and the driven boundary condition at the reservoir
at $y=0$ is described by a constant gradient of the chemical potential.
(b) The profile of the chemical potential $\mu(x,y)$ along the
$y$ axis at successive time steps $t_1 < t_2 ... < t_4$.
(c) The profile of the density field $\phi(x,y)$ along the
$y$ axis at successive time steps corresponding to (b). Note that due to
the conservation law these profiles have a finite slope in the wet region
of the medium.
(d) A set of typical rough front configurations of a rising interface $H(x,t)$
taken at equal time intervals $ \Delta t = 80$.}
\label{Configuration}
\end{figure}

\begin{figure}[t]
\includegraphics [height = 6cm, width = 6cm]{G2_v005_xi.eps}
\includegraphics [height = 6cm, width = 6cm]{StrFinal.eps}
\caption{(a) Spatial correlation functions $G_2(r,t)$ for a system
of size $L = 256$, with $\Delta \alpha = 0.3$, $v = 0.05$ at
different times. The data are from $t = 10^3$ to $ t = 10^4 $ at
equal time intervals of $ t = 2 \times 10^3$. In the inset, the
crossover lengths $\xi_\times(V)$ obtained from $G_2$ for
different velocities are plotted. (b) The
structure factor $S(k,t)$ plotted against the wave vector $k$ for
the same set of parameters as in (a). In the inset, the structure
factor obtained from the linearized interface equations is plotted
against $k$ for the corresponding set of parameters, except that
$L = 512$.} \label{CorrelationFigure}
\end{figure}

\begin{figure}[t]
\includegraphics [height = 6cm, width = 6cm]{WidthCollapse.eps}
\caption{Data collapse of the interface width according to the
scaling form of Eq. \eqref{CollapseForm} for different sets of
parameters with $L=256$: (i) $\Delta \alpha = 0.3$, $v= 0.05$ and
$0.01$; (ii) $\Delta \alpha = 0.2$, $v= 0.01, 0.005$, and $0.002$;
(iii)  $\Delta \alpha = 0.1$, $v= 0.005, 0.002$, and $0.001$. The
inset shows the original interface width data. }
\label{DataCollapse}
\end{figure}

\begin{figure}[t]
\includegraphics [height = 6cm, width = 6cm]{C2tInsert.eps}
\includegraphics [height = 6cm, width = 6cm]{CqtWithTd.eps}
\caption{(a) The temporal correlation function $C_2(t)$ for $L =
256$, with $\Delta \alpha = 0.2$ and $v=0.015, 0.01$, and $0.005$.
In the inset, the corresponding data are shown for the linearized
interface equations. (b) Temporal correlation functions $C_q(t)$
with $q = 2, 4$, and $6$ for $L = 256$, with $\Delta \alpha = 0.2$
and $v=0.015$. In the inset, the the corresponding functions are
shown for the linearized interface equations. See text for
details.} \label{TemporalFigure}
\end{figure}

The interface fluctuations in the presence of quenched disorder
were analyzed by numerical integrations of Eq. (4) with the
appropriate boundary conditions shown in the schematic
representation of Fig. \ref{Configuration}. In order to implement
the von Neumann boundary condition at $y=0$, Eq. (4) is modified
as follows:
\begin{eqnarray}
\partial_t \phi({\bf x},t) & = &  \nabla^2 \left[
- \phi({\bf x},t) + \phi^3({\bf x},t) - \nabla^2 \phi({\bf x},t) -
F H_0(t)-\alpha({\bf x})\right],
\label{Num}
\end{eqnarray}
where the addition of the term $F H_0(t)$ ensures that the
interface will propagate at constant velocity $v \equiv \dot H_0 =
F/2$ due to the boundary condition $\partial_y \mu|_{y=0} = -F$.
The above equation is then solved with the Dirichlet boundary
condition $\mu|_{y=0} = 0$. This is a numerical trick invoked to
obtain a chemical potential profile consistent with the von
Neumann boundary condition in the domain from the reservoir at
$y=0$ to the interface at $y=H$. The position of the interface
$H(x,t)$ at each $x$ was defined as $H(x,t)=0$ by linear
interpolation between the points of the numerical grid. Without
any loss of generality, the chemical potential at the boundary is
chosen such that $\mu(x,y=0)=0$, leading to $\phi (x,y=0) =
\phi_0$, where $\phi_0$ is the solution of $-\phi_0 + \phi_0^3 = F
H_0(t)$ \footnote{It should be pointed out that the von
Neumann boundary condition can
also be implemented directly by using $\mu(y = 0) = \mu(y = \Delta
y) + F \Delta y$, where $\Delta y$ is the size of the spatial
discretization. The numerical implementation of the von Neumann
boundary condition is then used to fix $\phi(x, y = 0) = \phi_0$,
where $\phi_0$ is the solution of $-\phi_0 + \phi_0^3 = -\phi(x,y =
\Delta y) + \phi(x,y = \Delta y)^3 + F \Delta y$. We have
compared the two different implementations and found no
distinguishable differences.}.

Typical plots for the chemical potential and the density field
along the $y$ axis obtained from numerical integration of Eq.
\eqref{Num} without quenched disorder ($\Delta \alpha = 0$) are
shown in Figs. \ref{Configuration} (b) and (c), respectively. A
set of successive interface configurations with $v = 0.02$, and
$\Delta \alpha = 0.2$ are also shown in Fig. \ref{Configuration}
(d). It is interesting to note from Fig. \ref{Configuration}(c)
that behind the moving interface the density field has a finite
slope, which remains constant in time. This is due to the
underlying local conservation law for $\phi(x,y)$. We note that
the slighly growing value of $\phi$ which is greater than $+1$ is
just a numerical artifact and can be removed by using a method of
moving box to hold the interface at a constant height, {\it i.e.}
pulling down the disorder field at constant time intervals.

\subsection{Spatial roughness}

With $\Delta \alpha > 0$, the driven wetting front kinetically
roughens as can be seen in Fig. 1(d). To characterize the spatial
extent of the roughness, we first consider the spatial two-point
correlation function
\begin{eqnarray}
G_2(r,t) = \langle \overline{[h(x+r,t) - h(x,t)]^2}
\rangle^{1/2},
\end{eqnarray}
which is directly related to the structure factor $S(k,t) \equiv
\langle \overline{h_k (t)  h_{-k} (t)} \rangle$. In the above
equations the brackets denote an average over different
configurations of random noise, and the overbar a spatial average
over the system.

In Fig. \ref{CorrelationFigure}(a) we show numerical data for the
spatial correlation function. We find that the correlation length
of the roughness of the interface saturates after an initial
growth. According to Eq. \eqref{cross}, the crossover length
$\xi_\times$ is related to the interface velocity by $\xi_\times
\sim v^{-1/2}$. In the inset of Fig. \ref{CorrelationFigure}(a) we
plot the velocity dependence of the corresponding crossover length
$\xi_2$ found from $G_2(r)$. We indeed find that this length
$\xi_2 \sim v^{-0.45}$, which means that $\xi_2 \propto
\xi_\times$ as in the case of spontaneous wetting, too
\cite{dubeprl}.

An estimate for the global roughness exponent $\chi$ can be
obtained from the structure factor $S(k,t)$, as shown in Fig.
\ref{CorrelationFigure}(b). As expected, we find that $S(k) \sim
1/k^{1+2\chi}$ is well satisfied, with a global roughness exponent
of $\chi \approx 1.25 $, and a crossover to a plateau
corresponding to distances larger than the intrinsic correlation
length $\xi_\times$, consistent with
the analysis from the linearized interface equation. We actually
found that the global roughness exponent slightly depends upon the
velocity and increases with decreasing velocity until
asymptotically approaching a value of about $1.35$. For velocities
$v=0.005, 0.002$, and $0.001$, with $\Delta \alpha = 0.1$,
it was found that  $\chi \approx 1.27,
1.35$, and $1.37$, respectively. Moreover, that global roughness
exponent slightly depends on the strength of the noise. For
example, for $v=0.005$, $\chi \approx 1.27$ and  $1.36$ for
$\Delta \alpha = 0.1$ and $0.2$, respectively. We also compared
the crossover lengths obtained from $G_2(r,t)$ to those from
$S(k,t)$,
and found that the value of $\xi_\times$ from $S(k,t)$ is
about one-half of that from $G_2(r,t)$, independent of disorder strength.

We also estimated the the local roughness exponent $\chi_{\textrm{loc}}$
according to the scaling relationship
$G_2(r = 1, t) \sim \xi_\times^{\chi-\chi_{\textrm{loc}}} \sim
v^{(\chi_{\textrm{loc}}-\chi)/2}$ for different velocities \cite{dubeprl},
and found that
$\chi_{\textrm{loc}} \approx 1.0$, as expected for superrough interfaces.
The spatial
correlation funnction $G_2(r,t)$ should also follow the same scaling form
$G_2(r,t) \sim \Delta \alpha v^{-\chi/2}g(rv^{1/2})$ as
$G_2(r,H)$ for spontaneous imbibition with fixed interface front height
\cite{dubeprl}.

\subsection{Temporal roughness}

To quantify the temporal development of the roughness, we consider
the width of the interface defined by
\begin{eqnarray}
w^2(t) =  \langle \overline {(h(x,t)-
\overline {h(x,t)})^2 } \rangle.
\end{eqnarray}
In the presence of quenched disorder the roughness initially
increases as a power law of time, as shown in Fig.
\ref{DataCollapse}. After a crossover, the roughness reaches a
saturated regime. For small $\Delta \alpha = 0.1$, only relatively
low velocities were studied, because for velocity as high as
$v=0.05$, the roughness profile shows pronounced oscillations. The
cause of such numerical oscillations was identified to be the
numerical interpolation of the interface position between the grid
points with time scale equal to lattice size over the velocity. It
can be clearly seen from the inset of Fig. \ref{DataCollapse} that
for the same noise strength, all the roughness curves follow the
same initial growth profile, suggesting an universal growth
exponent $\beta$. It was found that for $\Delta \alpha = 0.1,
0.2$, and $0.3$, the corresponding values of $\beta$ are about
$0.48, 0.50$, and $0.52$, respectively.

The saturated width of the interface was found to be independent of
the lateral system size as long as the lateral system size is larger
than the intrinsic crossover length $\xi_\times$, which has been
derived from the linearized interface equation in the preceding
section. It should be pointed out that in Ref. \cite{alava04}, where
the case of driven wetting was briefly discussed, it is claimed that
after an initial growth, the interface roughness follows a weak
logarithmic growth. From Fig. \ref{DataCollapse} one can see that we
do not find any evidence of such a logarithmic growth regime,
although it could be too slow to be detected numerically.

Assuming that the crossover length $\xi_\times$ controls the
roughening process, we can use the results in Ref. \cite{dubeprl}
and write a Family-Vicsek type of scaling relation
\begin{equation}
\label{CollapseForm}
w(t)=\Delta\alpha\xi_\times^{\chi}g\left(\frac{t^{\beta}}{\xi_\times^{\chi}}\right).
\end{equation}
Data collapse using this scaling from is presented in Fig.
\ref{DataCollapse}. Using the data collapse, we give our best
estimates for the roughness and growth exponents as $\chi  = 1.35
\pm 0.05$ and $\beta = 0.50 \pm 0.02$. We note that Ref.
\cite{alava04} estimates that $\chi \approx 1.25$ and $\beta \approx
0.4$, with $\beta=\chi/3$. However, our results do not support this
relation.

In the case of spontaneous imbibition, it was found that the rough
interfaces obey temporal multiscaling, with different scaling
exponents for different moments of the time-dependent correlation
functions \cite{dubeprl}. These functions and the corresponding
exponents are defined by
\begin{eqnarray}
C_q(t) =   \langle \overline{[H(x,t+s) -H_0(t+s)- H(x,s)+H_0(s)]^q}
\rangle^{1/q},
\end{eqnarray}
for $q=1,2,3,...$. The correlation functions $C_2(t)$ are shown in
Fig. \ref{TemporalFigure}(a) for different velocities. The crossover
time $t_\times$ between the power law regime of $C_2(t)$ and
saturation increases with decreasing velocities. The different
functions $C_q(t)$ for $q = 2, 4$ and $6$ are shown in Fig.
\ref{TemporalFigure}(b). At early times all the functions follow
power law behavior $C_q(t) \sim t^{\beta_q}$, with exponents $\beta_q \approx 0.94$
which are independent of $q$.
This behavior is, however, observed only in time scales
smaller than the disorder persistence time $t_d=\Delta y/v$, where
$\Delta y  = 1$ is the dimensionless spatial discretization step. If
we consider $C_q(t)$ for $t>t_d$, we find evidence multiscaling with
$\beta_2 \approx 0.79$, $\beta_4 \approx 0.69$ and $\beta_6 \approx 0.54$
in a small time regime, similar to the spontaneous case
\cite{dubeprl}. However, it is difficult to verify true multiscaling
here because of the rapid crossover to the saturated regime,
although we do expect avalanche type of motion to be present here,
which often leads to multiscaling behavior \cite{leschhorn94}.

\subsection{Numerical Results from the Linearized Interface Equations}
\label{numerics_interface}

An interesting question concerns the range of validity of the
linearized interface equation (LIE), Eq. \eqref{fluct_int}, for the
fluctuations of the height, in particular in the driven, nonlinear
regime with noise included. This issue is also related to the
possible existence of universality classes of roughening for
conserved systems with quenched noise; a problem for which there are
virtually no analytical results. To this end, we have integrated Eq.
\eqref{fluct_int} numerically in time. To incorporate the nonlinear
nature of the disorder $\eta(x,H(x,t))$, a back-and-forth Fourier
transformation scheme is required at every time step. A square
lattice landscape of independently Gaussian distributed noise was
used for $\eta(x,y)$. We note that solving Eq. \eqref{fluct_int}
instead of the full 2D phase field model is numerically much easier.

To compare the results with the phase-field model, we numerically
computed the same set of correlation functions. From the analytic
derivation of the interface equation, we can obtain a quantitative
map between the parameters of the phase field model and the
interface model, which is as follows. The interface velocities
should obviously be the same. The disorder fields between the models
are related by $\eta=M\alpha$, where $M$ is the mobility in Fick's
law. In our dimensionless units $M=1$. The effective surface tension
in the phase field model is given by the standard form of the
potential $V(\phi)$ as $\sigma_{pf}=\int
du~(\partial_u\phi_0(u))^2$, where $\phi_0$ is the 1D kink solution
of the disorder-free system. The surface tension in the interface
equation comes out as $\sigma=M\sigma_{pf}$.

The results from the LIE are collected in the insets of the
corresponding phase field results in Figs. 2-4. Obviously, the
length scale $\xi_\times$ is present in an identical manner in both
cases. Remarkably enough, the corresponding results from the two
cases are in most cases quantitatively close to each other. There
are some important differences, however. First, the saturated
interface widths differ by about $20\%$, the interfaces from the LIE
being rougher. Since the interface model only takes into account
linear dissipation effects, we would expect it to underestimate the
stiffness of the interface, leading to larger roughness amplitudes
than in the full phase field model.

Next, we examine the data collapse for the interface roughness (Fig.
\ref{DataCollapse}) using the scaling function of
Eq.~\eqref{CollapseForm}. The best collapse is obtained for slightly
different values of the exponents as compared to the phase-field
model. The roughness exponent is close to the previous value, namely
$\chi=1.27 \pm 0.05$. However, the growth exponent is now given by
$\beta=0.37 \pm 0.04$ for the LIE, where the difference to the phase
field result is outside of the numerical uncertainties. In the LIE
we also noted a slight deviation from the behavior of the crossover
time $t_\times \propto \xi_\times^{\chi/\beta}$ as a function of the
disorder strength $\Delta\alpha$.
Another difference between the two models was found in temporal
multiscaling. In the LIE each of the moments increases with a
different exponent $\beta_q$ even at times smaller than the disorder
persistence length $t_d$. The exponents are $\beta_2 = 0.75
\pm0.03$, $\beta_4 = 0.55 \pm 0.05$, and $\beta_6 = 0.47 \pm 0.03$.
The values of these exponents are lower than in the phase-field
model, which is not surprising since the LIE has a lower value of
$\beta$, too.

\section{Summary and Conclusions}
\label{conclusions}

In the present work, we have studied wetting of a disordered medium
driven by a constant mass flux in a 2D system. Our model is a
prototype phase field model incorporating mass conservation into the
flow of two immiscible fluids, Eq. \eqref{pf_eq}. From this model we
have derived non-local interface equations to lowest order in
Fourier space fluctuations, Eqs. \eqref{ave_int} and
\eqref{fluct_int}. Because of the linearization, these equations are
local in Fourier space. The constant flux boundary condition gives
rise to a interface that moves with a constant velocity proportional
to the flux. We have obtained a time-independent crossover length
scale $\xi_\times \propto \sqrt{\sigma/v}$ from the
interface equations. Numerically, we find that the kinetic
roughening of an interface is governed by a scaling relation of the
Family-Vicsek type, where $\xi_\times$ controls the extent of the
fluctuations (for $\xi_\times < L$) as given by Eq.
\eqref{CollapseForm}. For the kinetic roughening of the interfaces,
we find that they are superrough, with $\chi = 1.35 \pm 0.05$ and
$\chi_{\rm loc} \approx 1$. For
temporal roughness, $\beta=0.50 \pm 0.02$, and there is numerical
evidence of temporal multiscaling for $t>t_d$. We note that all
these results are in qualitative but {\it not in quantitative}
agreement with the case of spontaneous imbibition studied earlier in
Refs. \cite{dubeprl} for interfaces, which are kept at
constant height in the steady-state regime described by Washburn's
law.

In addition to obtaining the LIE by analytic methods, we have also
made a direct comparison between it and the full phase field model
with quenched noise properly included. We find very good agreement
between the spatial correlations of the interfaces, even including
approximately the same roughness exponent of $\chi \approx 1.3$.
However, the temporal correlations in the two cases are different:
while the amplitude of the saturated roughness is larger in the LIE,
but the growth exponent $\beta = 0.37 \pm 0.04$ is smaller than the
phase-field result $\beta = 0.50 \pm 0.02$ in the phase field model.
Also, spatial multiscaling is more clearly present in the LIE within
our numerics.

Our analytical and numerical results of forced wetting can be
compared with experimental results of kinetic roughening of an
oil-air interface in a forced wetting where the experiments were
done in a horizontal Hele-Shaw cell with quenched disorder
\cite{SOH1}. It was found in the experiments that the growth
exponent $\beta \approx 0.5$ which is nearly independent of the
experimental parameters, and the roughness exponent $\chi \approx
1.3$, which, however, depends on experimental parameters. While a
fully quantitative comparison may be difficult, both exponents
obtained experimentally are in very good agreement with our
numerical results. Furthermore, the experiments confirm that the
crossover length scales as the inverse of the square root of
velocity, as found in our theory. Further experiments on the
dependence of the results on other systems parameters would be most
interesting.

\section*{Acknowledgments}
This work has been supported in part by the Academy of Finland
through its Center of Excellence grant. We would like to thank M.
Alava and M. Dube for their insightful comments.

\section*{Appendix}

redpajama_set_name: RedPajamaArXiv


text:
Polyacanthonotus è un genere di pesci ossei abissali appartenente alla famiglia Notacanthidae.

Distribuzione e habitat
I membri del genere si incontrano nell'Oceano Atlantico, nell'Oceano Pacifico e nel mar Mediterraneo dove vive la specie Polyacanthonotus rissoanus.

Specie
Polyacanthonotus africanus
Polyacanthonotus challengeri
Polyacanthonotus merretti
Polyacanthonotus rissoanus

Note

Collegamenti esterni

Notacanthiformes

redpajama_set_name: RedPajamaWikipedia


Vince Brown, not Vincent Jackson, led all Chargers receivers Thursday night with five catches for 97 yards and a single TD lending speculation that Brown could become the next mentionable waiver wire add.
Fantasy Impact: Brown looked exciting and he looked very sharp for a youngster in a complex offense, but his fantasy potential rest on how long Malcom Floyd remains injured, which isn't expected to be very long. Another issue to remember for next week is the fact that the Chargers face a Bears defense that is much better at getting to the quarterback than Oakland is, and Oakland tore apart that San Diego front five. Brown should be on your watch list, but he is nothing more than a boom or bust player right now.


text:
KLENOTA Jewellery
Gems and pearls
Back Gems and pearls
Gemstone cutting: an exact craft with a tradition
A gemstone in its natural, uncut form is often indistinguishable from an ordinary stone. It is only by being cut and polished that it becomes beautiful. When it is cut, it allows the gemstone to shine to the fullest and to show off its hidden beauty of colours, sparkle and other unique properties. In this article, we will reveal the process of the very precise and traditional craft of gem cutting.
The origins of gem cutting
Mineralogy as a science in the true sense of the word only began to develop roughly at the end of the 18th century. Until then, the study of gemstones was more akin to fortune-telling from a crystal ball and in the Middle Ages, Europeans were far behind the Arabs in this field. In 1048, a treatise written by Abu Rayhan al-Biruni described various techniques for cutting stones and the knowledge discussed in this work probably then spread to European territory.
We can judge what gem cutting was like in the Bohemian lands in the 14th century during the reign of Charles IV by looking at the St. Wenceslas crown or the paneling of the Chapel of the Holy Cross at Karlštejn. The shape of the cuts on the stones already suggests a more advanced level of cutting and polishing as well as the fact that certain techniques were used that were not yet commonplace at that time. Unfortunately however, we do not have any written records of these from this period.
A very important document describing the development of the gem cutter's craft and the methods of working gemstones is a document from the period of Rudolf II entitled Gemmarum et Lapidum Historia, published in 1609 by Anselmus Boetius de Boot. It is also the source of a picture of a quadrant, a cutting machine that allows a mineral to be cut into facets and rounded shapes, which is still used even today. In the 17th century, a major change came in the form of cutting the lower part of the stone into a point. Until this time, stones were cut with a flat base and this was the first time that light was to be intentionally used in minerals.
During the Renaissance, gem cutters were already able to cut minerals with a hardness of 8 on the Mohs scale. They used diamond abrasive pastes for this purpose, but because of the grittiness of these pastes, it left grooves in the gemstones. These are so typical of the period that they are one of the hallmarks when dating jewellery work from the Renaissance.
In Bohemia, the town of Turnov and its surroundings became the centre of gem cutting. In addition to minerals, glass, which was used in Jablonec jewellery also began to be cut here. The cutters later divided into two groups. One specialised in cutting minerals while the other in glassmaking and cut glass.
The most sophisticated way to finish off the look of precious stones is to cut the surface into many flat areas called facets. These have an important function since they reflect and transmit light depending on the angle at which the light strikes them. Each facet has a specific role. A stone which has been cut is an ingeniously thought out object that uses the principle of refraction from physics. The aim of cutting the stone is to reflect as much of the light entering the stone back through the table (the flat top of the stone) and the facets to the human eye.
Gem cutting methods in practice
It is absolutely essential for cutters to know the characteristics of the stone in question, as these will be their best guide for choosing the right cut. However attention also has to be paid to the specific stone being worked on and its particular qualities, which include transparency, the number of inclusions and, most importantly, the number of fractures. It is the gem cutter's job to choose the appropriate cut for the stone so that its best features stand out the most.
Diamond cutting
Diamond cutting requires special technology. The rough diamond is scanned before the process begins and a 3D model is then created in the computer. Based on this model and any imperfections it reveals, the most suitable shape and type of cut is then selected. When the diamonds are initially worked on, the way they cleave is used in the process. The area where the stone will be split is marked with a laser, then cut and split by a strike with a hammer or mallet. In professional workshops, special circular diamond saws are used to cut diamonds.
Diamond cutting companies
The most famous diamond cutting workshops were located in Amsterdam and later in Antwerp, where many Dutch cutters moved. An example is the well-known Coster Diamonds BV cutters which cut the famous Koh-I-Noor diamond that adorns the British Crown Jewels. The oldest diamond cutting company was Van Moppes Diamonds, founded in 1828. Many Dutch diamond cutters are renowned to this day, even though they are far from being the only cutters in the world anymore. Israel for example has become a competitor, where old Jewish families which originally came from Antwerp continue the tradition. Other current gem cutting centres are in India, China and Africa.
Assessing gemstone cuts
Each cut has clearly defined parameters that must be followed to maximise the use of the light. However this does not always happen. It may be due to a poor choice of cut that does not match the shape of the raw stone or a deliberate failure to adhere to the guidelines in order to increase the carat weight (and thereby also the price) of the final piece. This assessment category is called proportion and it is very much taken into account.
Small details that can only be seen through careful examination with a magnifying glass are also taken into account when evaluating the cut. The gemologist observes the size and symmetry of the individual facets, their sharpness and mutual continuity, the symmetry of the entire cut as well as the good centering of the main facets. The surface finish is also very important and the quality of the polish on the stone is taken into account. The surface should be completely smooth and without any scratches.
The internal characteristics of the stones such as its brilliance, fire and scintillation are also assessed. Brilliance is the degree of white light reflected. Fire on the other hand refers to the number of spectral colours which the light coming out of the diamond breaks down into. Scintillation occurs when the diamond is moved from side to side and the amount and pattern of light and dark areas within the stone is also assessed in this category.
A sophisticated system designed by the GIA helps when grading the cuts on diamonds. It divides diamonds into five categories.
The best quality diamonds are designated EX and account for approximately 3% of the world's total diamond production. They are just about perfect and reflect almost all of the light that hits them.
VG diamonds are a close second. To the untrained eye, they are indistinguishable from completely perfect diamonds. They reflect almost all the light that hits them, but they are not quite perfect. They account for about 15% of the world's total production.
The happy medium is called G. About a quarter of diamonds which are cut fall into this category. They reflect most of the light.
In fourth place are diamonds rated F. This is still considered to be a quality cut but these diamonds shine much less than the previous ones.
Poor cut
The final fifth place is referred to as P. These cuts are rated as poor and do not meet the criteria for a quality cut. Light is practically not reflected back at all and leaks through the diamond. The stone appears dark, it doesn't sparkle and it is not attractive.
The gemstone cuts used in KLENOTA jewellery
KLENOTA jewellery is typically set with stones with a quality rating of VG. A traditional and very popular cut, especially for engagement rings, is the brilliant cut. However we also like to work with less traditional cuts such as the heart, asscher, princess, emerald and others at our studio. The visual quality, size and symmetry are all crucial for these cuts, since they affect the overall impression of the jewellery as well as the quality of the setting – that is, that the stone fits perfectly in the ring and doesn't fall out over time.
Stone setting is a master craft in the jewellery industry and requires top quality control and excellent stone setters. We have devoted a separate article on our blog just to this topic and In it you'll find out how this precise craft evolved and how we set stones into jewellery nowadays.
Jewellery right for you
Did you like the article? Then you might also like these jewels.
Diamond £2 219
Diamond & Diamond £5 149

redpajama_set_name: RedPajamaCommonCrawl


text:
Home Entertainment How Can Gaming Improve Your Social Life?
How Can Gaming Improve Your Social Life?
The media often presents gamers as antisocial, rather nerdy beings that spend all day cloistered in their gaming dens, eating junk food and seeing little of the outside world. Statistics, however, indicate that this image is a mere myth. Approximately 78% of gamers in the US feel that gaming plays a major part in making new friendships and improve your social life.
Some make new friends when they sign up for a game, while many others strengthen relationships with work colleagues and classmates by 'hanging out' together online. If you love nothing more than getting together with friends but you also enjoy challenging yourself with your favorite game, read on to discover why you shouldn't stop.
Online Gaming Helps Foster Lasting Relationships
Finnish academics have found that multiplayer games are far from isolating. In fact, they typically encourage players to interact by making them compete against other teams or making teamwork necessary to reach higher levels in a game. Some games provide players with tools for interaction and for communication between groups and communities. It is also typical for players to connect between games via email, on the phone, and even face to face.
Modeling Friendly Support
If you play social games like Animal Crossing, then you know that good vibes and positive interaction are encouraged in many top-rated games. Popular Animal Crossing characters like Cookie, for instance, are always there to chat and take part in activities together (practicing being pop stars, or heading to a natural spot).
These characters model good behavior, as it were, especially for younger players. They openly discuss their thoughts and feelings, with some characters being particularly well known for their caring, supportive nature. When players are engaged in games with other human beings, they can model the language used by their favorite characters and up the fun factor by engaging in activities with friends and characters simultaneously.
Forming Part of a Community
Harvard Divinity School Professor, Casper ter Kuile, states for many millennials, community activities are taking the place of spiritual gatherings such as community worship or church-going.
Ter Kuile believes that group activities can offer the sense of community and accountability that was once offered by religious congregations. This sentiment is echoed by author, Craig E. Mattson in his book, Why Spiritual Capital Matters: Activating Latent Resources in Your Organizational Community.
Mattson argues that human beings today are exploring sites of deep community outside of religion, "whether it's fitness communities or gaming communities." What is it that makes gaming a potential source of connection to something greater than oneself? The answer is shared values, support from fellow players, unconditional acceptance (even if you have had a 'bad game') and a sense of joy in togetherness.
Gaming in modern times is a vital and popular way to connect with others. Research has shown that many players form lasting friendships through this hobby, with some finding additional ways to connect, such as via telephone and in-person get-togethers. Gaming is also providing many people with a powerful sense of community that helps them feel more spiritually connected to others.
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text:
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redpajama_set_name: RedPajamaGithub


Prabhakar Chavhal, 30, has a tougher job than his uncle, Shivaji Chavhal, 55. Both are farmers in Moregaon village in Marathwada's Parbhani district. Both mainly grow cotton. But while Shivaji's cotton had for years been a cash crop, Prabhakar's same crop no longer brings much cash.
The Chavhals are not alone. Parbhani, Hingoli and Aurangabad districts in Marathwada nurture vast cotton belts – 17.60 lakh hectares, according to the state agriculture department. The crop used to generate higher returns as compared to food crops such as jowar, tur and soyabean – the reason cotton is called a 'cash' crop. However, the production cost of cotton has risen over the years, while the returns have remained almost stagnant, turning cotton into a cash crop in name only.
Prabhakar explains the slide in detail. He takes out a piece of paper on which he has written all the expenses he incurs to cultivate one acre of cotton – Rs. 800 for a bag of seeds, Rs. 1,100 as wages to labourers to prepare the land ahead of the sowing period in mid-June, and Rs. 400 more at the time of sowing. If the monsoon rains are good, he will need to remove the weeds in three phases, which is another Rs. 3,000 as wages. Fertilisers? Rs. 3,000 more. Pesticides come to Rs. 4,000. Harvesting costs are Rs. 5,000.
And it's not over yet. The final hurdle is selling it in the market, which costs Rs. 3,000 per harvest, including transport and commissions to be paid to traders.
"It adds up to 20,300 rupees per acre," Prabhakar says. The anticipated market rate this year, when he harvests his cotton in November-December, is Rs. 4,300 per quintal (last year it was Rs. 4,000). "The income [after all costs] is 34,800 rupees," he says. So eight hard months of work and investments yields just Rs. 14,500 per acre. And then Chavhal has to pay electricity bills for the water pumps and borewells — and spend more than Rs. 14,000 per month on his six cows.
Around 15 years ago, Shivaji Chavhal was able to cultivate an acre of cotton for Rs. 4,500-5,000. The pesticides, fertilisers and seeds used to cost less than half of what they cost now. Daily wages of agricultural labourers have also more than doubled. Electricity costs too have risen.
Prabhakar's 15-member joint family, including his uncle Shivaji, owns about 30 acres of farmland, of which 15 acres used to be reserved for cotton. They have reduced it to 7-8 acres over the past four years, replacing the cotton with food crops like tur, moong, urad and soyabean.
Cotton is a thirsty crop, requiring much more water than food crops. Four years of drought from 2012-2015 in Marathwada played havoc with cotton yields. This year, too, the rains have been inconsistent. The dry years have forced farmers to spend more on irrigation – by drilling borewells, purchasing water tankers, or digging wells.
The price of cotton though, has not gone up in the same proportion. "The market rate for cotton was around 2,000 per quintal [15 years ago]," says Chavhal. "Eight quintals of produce on an acre meant 16,000 rupees. The profit was about 11,000 back then – just 3,000 rupees less than what we now make, 15 years later."
The low price is due to various factors, including the government's refusal to consider the rising input costs when fixing the minimum support price (MSP) for the crop. Another reason, says Vijay Javandiya, veteran farm leader, is that the price of cotton in the international market is heavily subsidised for the American cotton grower, which negatively influences a fluctuating domestic rate in India. "Also, though both sugarcane and cotton are cash crops, different yardsticks are applied to them," he says. "When there is a glut in the market, sugar is exported with subsidies so it does not affect the prices so much. There are no subsidies to export cotton. Similarly, there is 50 per cent import duty on sugar, while there is no import duty on cotton."
While cotton farmers are being squeezed between mounting costs and stagnant returns, a single medical emergency, a marriage in the family, or even the added cost of school fees can force them to apply for a bank loan. Or, worse, approach a private moneylender, who typically charges an exorbitant 5 per cent interest per month.
In 2006, the Swaminathan Commission, which was set up on the directive of the Congress government to assess the farm crisis and come up with solutions, submitted its report. One of its major suggestions was that the central government provide an MSP to farmers that would add up to the cost of production plus 50 per cent. But the government did nothing. In 2014, the opposition Bharatiya Janata Party campaigned vigorously in agrarian areas, promising to enforce the report, but after coming to power has not implemented the report's recommendations.
Asaram Lomte, a senior journalist and Sahitya Akademi award-winner based in Parbhani, says for farmers used to cultivating cotton, alternatives such as tur or soyabean aren't promising either because these crops too are not being given a fair MSP, and returns on such food crops are anyway relatively low.


From then to now, nothing has been the same. U.N. paramilitaries occupy the country. Washington effectively controls it. President Rene Preval got a choice – go along or pay the price. He submitted knowing what awaits him if he resists. Nonetheless, he's disappointed bitterly.
At the same time, huge crowds massed in front of the National Palace awaiting a Clinton, Ban Ki-moon, Preval press conference. They had signs, banners, and T-shirts displaying Aristide's image, and from a sound truck asked Clinton to tell Obama that since the "kidnapping of our president … [our] situation has only worsened." One demonstrator told Haiti Liberte: "We are waiting for the soonest possible return of the president….and if Lavalas is not part of the elections, free and fair [ones] will not take place." In addition, Preval was denounced as a traitor, and repeated chants were "Down with the MINUSTAH," the UN paramilitary occupiers.


The Literary Resistance Book Club is live! What started on the blog as a response to the election has become a real life meetup!
It took some courage to get it off the ground. After all, I've never been the host of a book club before. I wasn't sure if anyone would want to come, but I was mistaken. The first two meetups have been a success. I even have plans to take it on the road this summer as I do some traveling. I can already imagine a network of Literary Resistance Book Clubs popping up across California!
If you're in the Bay Area and interested in joining you can find more info here. It's a rather non-traditional book club. Instead of collectively deciding on a book and reading it together, all I ask is for each person to bring a book they'd like to share with the group. I was a bit worried that conversation would be stuttered, but people are curious and have no problems asking questions about each book. This naturally leads to discussion.
A lot of interesting books have been brought to the table. A few are new to me, The Looting Machine: Warlords, Oligarchs, Corporations, Smugglers, and the Theft of Africa's Wealth; Waste Away: Working and Living with a North American Landfill; Dark Money: The Hidden History of the Billionaires Behind the Rise of the Radical Right; and Culture and Society. A few others I knew and was eager to discuss, Stranger's in Their Own Land: Anger and Mourning on the American Right and Between the World and Me.
For my pick I brought Secondhand Time: The Last of the Soviets by Svetlana Alexievich. I've talked about it on the blog a couple of times already, it's just that I'm in such awe of her writing and the stories she captures. The book also sent me down a Russian rabbit role.
I've since devoured Masha Gessen's book The Man Without a Face: The Unlikely Rise of Vladimir Putin in time to see her speak at the Bay Area Book Festival. Masha is a Russian and American journalist and outspoken critic of Putin. When she was asked how she felt about the current state of Russia, her home country, she solemnly replied, "hopeless". This is the sense I get from reading Secondhand Time, a sheer and terrifying sense of hopelessness.
Hopelessness is what I hope literary resistance can prevent. I don't want to lose my own sense of power to make a difference. Use #literaryresistance to let me know what you've been reading and how your reading is making a difference.


One year ago today, a fertilizer plant in West Texas blew up and killed 15 people, injured 160 and flattened dozens of homes.
Thursday, April 17, 2014 is the one year anniversary of the West, Texas fertilizer storage facility explosion, a disaster that devastated a community, claimed 15 lives, and injured over 160 others. The West Fertilizer Company supplied chemicals to farmers since it was founded in 1962, and was last inspected by the Occupational Safety and Health Administration in 1985.
In the aftermath of the explosion, the operator of the fertilizer plant was cited for 24 safety violations and charged $118,300 in penalties. Safety violations included exposing workers to explosion hazards and chemical burns, unsafe handling and storage of chemicals, failing to have an emergency response plan and not having an appropriate number of fire extinguishers.
The US Chemical Safety Board reported that regulation of the dangerous chemicals used in the industry fall under shoddy standards that are dated and far weaker than standards in other countries. However, Texas, which has the country's highest number of workplace fatalities, is still wary of regulations.
During the government shutdown 90% of CSB employees were furloughed, causing a delay in the investigation of the West, Texas disaster.
Please sign this petition here to tell the EPA to increase standards for chemical safety, work harder to ensure responsible chemical storage and transportation, and mandate that companies replace dangerous chemicals with safer alternatives.


Mining in Zimbabwe Zimbabwe's mining industry is focussed on a diverse range of small to medium mining operations. The most important minerals produced by Zimbabwe include gold, asbestos, chromite, gold and base metals.
Increase of area of mining lease. 155. Abandonment of portion of mining lease. 156. Total abandonment of mining lease. 157. Failure to comply with terms and conditions of mining PART IX SPECIAL MINING LEASES 158. Interpretation in Part IX. 159. Application for special mining lease. 160. Application of certain provisions of Part VIII to special mining leases.
Part XIII Zimbabwe Government Mining Diploma Part XIV Zimbabwe Government Mine Manager's Certificate of Competency Part XV Miscellaneous: Amending text(s): 1996-10-18 (ZWE-1996-R-45667) Mining (Management and Safety) (Amendment) Regulations, 1996 (No. 6) (S.I. 234 of 1996). 1996-08-09 (ZWE-1996-R-44864) Mining (Management and Safety) (Amendment) Regulations, 1996 (No. 5) (S.I.
Health and Safety Laws in Zimbabwe, All about Health and Safety Regulations in the Workplace, Sector Laws on Health and Safety and more on Mywage Zimbabwe Complete our Salary Survey and Win a Wage! What are the laws surrounding Health and Safety in the Workplace in Zimbabwe?
CWA-based regulations cover such mining-related situations as the disposal of mining-related waters, the pumping or draining of mine water to the surface, storm water runoff in mining operation areas, and control of seeps from mine tailings impoundments.
Occupational health and safety management in Zimbabwe is pursued through the International Labour Organizations Zimbabwe Office, the Ministry of Public Service, Labour and Social Welfare, the National Social Security Authority, and the Zimbabwe Occupational Health and Safety Council, which comprises government, employers and labour unions.
coal mining regulations in zimbabwe Zimbabwe: Mining Involves Many Safety, Health Hazards , 19 May 2015 , Mining requires extreme caution and the observance of safety regulations designed to minimise the dangers , shafts, outlets of underground mines to the surface, ventilation, gases, dust, mine surveying, gold mines and fiery.
Zimplats platinum mine in Zimbabwe was held up as a safety benchmark at the Joburg Indaba, which on Thursday observed a minutes silence for mining colleagues fatally injured at work.
Zimbabwe as a nation adopted the OHSAS18001 standard for occupational safety and health management. Any other OSH system must be in addition to this and not replace it.
Mining requires extreme caution and the observance of safety regulations designed to minimise the dangers inherent in mining and ensure the safety of miners.
The workshop discussed the legislative framework that guides mining and mineral resources in Zimbabwe. The mining sector in Zimbabwe is regulated by an Act of parliament (The Mines and Minerals Act [Chap 21:05]. The Act provides for security of tenure and has clear provisions for acquisition, maintenance and relinquishing of mining titles.
the Mining (General) Regulations; the Mining (Managements and Safety) Regulations; the Mining (Health and Sanitation) Regulations; the Mines and Minerals (Custom Milling Plants) Regulations; and; the Zimbabwe Investment Authority Act deals with investment coming into the country and the necessary permits that investors need to work in the country.
Mineral Marketing Corporation of Zimbabwe Act Gold Trade Act Precious Stones Trade Act Base Minerals Export Control Act The Chamber of Mines of Zimbabwe (established by an Act of parliament) is the dominant representative body of the mining industry in Zimbabwe.
Mining job seekers in Zimbabwe Mining job seekers found in Zimbabwe save your resume searches for future reference. New resumes located in Zimbabwe are added daily on Careermine.


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Bowing With FiddlingMonk
Mind of the Monk
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violin - You have come to the right place!
Venture into the world of Kaleidoscopic sound of Indian
music under the guidance of Fiddling Monk (Kumaresh R).
ABHYASA - Prathama
This course is for beginners. If you have never learnt Violin before, this is where you start your musical journey.
ABHYASA - Dwitheeya
In this course, you will be learning - simple exercises to understand the swara positions, you will improve the Left-hand techniques, posture & learn how to shift from 1st to 5th position. You will master the techniques to playing on all 4 strings.
ABHYASA - Thritheeya
In this course, the student is made to understand the seamless movement of the left hand across multiple octaves on the Violin, through lucidly designed exercises and melodies.
ABHYASA - Chaturthi
This course is all about strengthening and enhancing the playing skill and technique of the Indian Violin. This course will enable you to get comfortable with playing the instrument and the musical notes with confidence and clarity.
CHOCOLATE MELODIES - Prathama
In this course, the student is introduced to the kaleidoscopic dimension of the aura and the sound of various Indian Ragams (Musical Scales) and Thalams (Rhythmic cycles), through small lilting compositions - Chocolate Melodies...
VARNAM - Prathama
In this course, the student gets to learn one of the most prominent and dynamic form of Compostions - Varnams. Introduction to Gamaka, which is an intrinsic sound & character of Carnatic Music. Ragams covered are Mayamalavagowla & Hamsadhwani.
VARNAM - Dwitheeya
In this course, the student gets to learn one of the most prominent and dynamic form of Compostions - Varnams. We are going to extensively look in to how to play the gamaka. Ragams covered in Dwitheeya are Mohanam and Abhogi.
A short prelude to what's coming soon ! Talapravahams, Kritis, Ragam Tanam Pallavis, Pancharatnams and much much more! Stay tuned for Master Classes as well as 1-on-1 Mentoring announcements. Click to learn more.
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Violin Maestro Kumaresh is a limitless phenomenon whose musical career spanning 48 years has created a paradigm shift in the way the world looks at Indian Violin.
An out of box thinker and a philosopher, Kumaresh, fondly known as the Fiddling Monk , has redefined the teaching methods and repertoire for the students of violin.
A Child Prodigy who played his first concert when he was just 5 years, he was a sensation in the field of Carnatic music by completing his 100th stage performance even before he was 10. There are many firsts in his career, like being one of the youngest to perform a full-fledged concert on stage, one of the youngest artists to be honoured as "The State Artist" , by the Tamil Nadu Government, to getting an "A Top" Grade by the All India Radio, and the list goes on! He is also a proud recipient of "Sangeeta Natak Academy" award, the highest award given to an artist by the Government of India (GoI)
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The portal is an ammmmaaazing experience, easy to navigate and the interaction sessions are very comfortable... I am just loving the portal. My heartfelt thanks to The Fiddling Monk for giving us an opportunity to learn the Indian violin"
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Bill Gates used to say that "Every employee in Microsoft should have be aware that Microsoft will go into liquidation three months later." Many people consider it as a puzzling thing and they wonder if Bill Gates is afraid of that the prophecy will someday come true. In fact, it's not like that.
As the saying goes, to stand still is to move back. It reminds us that it's common for us to meet with setbacks so that we must strive or we fail.
It implies an awareness of unexpected development and every one should possess it, foreign trader is no exception. In foreign trade, our colleagues are also our competitors. After all, leaders love to contrast their employees and attempt to find out if they have the ability to make contributions to the company.
And after hearing Katherine's feedback, I was enlightened from the blindness with profound understanding.
Katherine got into the saddle with some other persons. And at the very beginning, Katherine didn't get along well with her colleagues while through Katherine's efforts and her outstanding ability to communicate, they became close friends. And the friendships won by Katherine through her efforts seemed pretty precious.
It seemed that things were going smooth and just as Katherine was planning for the future with her intimate friends in the company in search of the bright future, the company arranged an examination. It related to the issues of exhibition so Katherine dared not relax and passed the exam successfully. Before Katherine could even delight, she heard that two colleagues of her who were also her intimate friends failed in the exam and got fired, afterwards. And Katherine's manager who had cultivated her chose to quit the job for this reason.
Katherine was covered with sorrow for her close colleagues and honorific manager left the company. In the company, there was one other salesperson who was good at developing customers apart from Katherine. Therefore, she was highly favoured by the boss and the boss promises to cultivate her to be a supervisor.
Additionally, the new manger wasn't Katherine's liking. Katherine begins thinking she was besieged on all sides and felt uneasy and nervous. She started to feel no intention of staying at the company. Katherine had no faith in herself and she supposed that she wasn't supposed to make any mistake, elsewise, she will be the next person who got fired.
Katherine turns to be overcautious and has doubts about everything she did. She becomes stress-out and has lost the spirit to try her best.
As 2018 came with the environmental protect taxes, the prices of raw materials raised due to a series of chain reaction which also led to nationwide rise in price. Plus there were some fairs round the corner so that some foreign trade companies took measures such as examination to select the salespersons, especially those upcoming salespersons.
As regards Katherine's lot, I suppose there is no need for her to be overcautious but learn to march forward despite the coming setbacks and pressure. Otherwise, she would only defeated by the era and her foreseeable future like getting fired wasn't far away from her.
Try to endure the loneliness. Despite those persons displeasing Katherine, she can still chin up and chest out in the company as long as she can be responsible for her occupations and make adequate preparations for the coming fairs.
Besides, since she has possessed the crisis awareness and realized the potential destabilizing factors, she should save for the rainy day and make sure she can escape unscathed even she gets fired instead of being overcautious since it's last thing foreign traders need to do.
You have no intention of advancing, your rival does. You have no intention of endeavouring, your rival does. You have no idea where the road ahead leads while your rival has advanced triumphantly. Everything may come all of a sudden while it's also likely to arise slowly. Bear in mind that to stand still is to move back.


Coming into the second floor, there is a corridor, from where you can enter into a 15,6m2 and a 13,6m2 sized bedrooms. The corridor leads to the kitchen with a dining-room, and a living-room with a balcony, with a beautiful view. From the living-room opens a 11,23 m2 sized room, and from the dining-room you can reach the bathroom with a toilet, the staircase and a back entrance as well.
The bedrooms have fitted carpet, the living room has parquet and the other rooms have tiled floor.
You can built the loft in, there is also a balcony.
In the ground floor there is a 26,6 m2 sized garage with an inspection pit. In the garage there is a gas heating boiler, which heats the entire house. Going further, you get to a 20,8 m2 sized room, which is now used as a workshop and a mixed heating boiler is located also here.
Going forward you can find a 18,3m2 sized kitchen, from where open a bath-, and laundry-room, a chamber and a 17,6m2 sized, very bright room. You can also find here the staircase, which leads to the second floor.
The doors and windows are made of double wood, equipped with shutters. The warm of the house is provided by the unique mixed and gas heating furnace. The house is connected to the industrial power.
The building is ideal for two generation, because the separate entrance is resolved.
To the house belongs to an outhouse and a railed off space where you can keep poultry.
In the yard you can find a cellar, where you can store vegetables, fruits, and vine and there is a nice garden, filled with beautiful flowers, and fruit trees, which is an entertainment for all ages.
I am interested in "Property for sale in Geresdlak - Hungary". Please contact me.


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The Durban University of Technology has produced and donating 3D printed face shields to selected communities in Durban. Picture: AP Photo/David J. Phillip
Covid-19: DUT donates 3D printed face shields to protect frontline workers
By Staff Reporter Apr 15, 2020
Durban - The Durban University of Technology has produced and donated 3D printed face shields to communities in Durban.
Some of these face shields have already been donated to Prince Mshiyeni Hospital, to various doctors around Durban, to the Berea SAPS and Aryan Benovelent Old Age Home in Chatsworth.
"The 3D printed face shields are produced at the University's Luban Workshop, situated at Ritson Campus in Durban. Using the 3D printing laboratory which has 12 high quality 3D printers, DUT saw a need to extend its hand to the Durban community during the global Covid-19 pandemic. In addition to the 12, 3D printers, DUT has two industrial Resin printers that could be used to print moulds to support large scale manufacturing processes," explained DUT's Alan Khan.
Khan said the concept of 3D printing refers to a process of additive manufacturing of three-dimensional real-world objects from a digital file. The process allows for the production of complex solid shapes using less material than the traditional manufacturing methods.
"Industries worldwide have proposed the application of 3D printing to curtail the pervasive outbreak of Covid-19 through massive production of equipment such as face shields, oxygen connectors, oxygen splitters, Venturi valves, masks, gowns and respirators," he said.
It only takes 24 minutes for each shield to be printed.
The shield protects the eyes, nose and the mouth which are known to be the main areas which the virus can enter a person.