text:
\section{Introduction} \label{sec:intro}
Astrochemistry is a complex web of processes that are hard to disentangle, as physical parameters affect the chemistry of the interstellar medium (ISM) in different ways. The cosmic-ray (CR) ionization rate, $\zeta_{\rm CR}$, is the important ingredient that leads the way for ion-neutral reactions by ionizing neutral atoms and molecules. In particular, deep inside molecular clouds CR particles are the sole source of ionization, as the thick material shields the inner regions from ionizing UV photons \citep{2009ApJ...694..257I}. In extreme environments CR ionization can drive the formation of species but also destroy them as molecules are ionized and quickly dissociated due to a large amount of free electrons.

CRs are predominantly charged particles, with protons being the dominating component, and smaller contributions from electrons, positrons, and bare nuclei of helium and other heavy elements \citep[see, e.g.][for a thorough review]{2012PhRvD..86a0001B}.

But the origin of CRs is still not fully understood. It is impossible to directly pinpoint the point of origin as the charged CR particles\footnote{In the following we use the terms cosmic rays (CRs) and cosmic-ray particles synonymously.} are deflected and redirected by the Galactic magnetic field. Additionally, disentangling the direct CR contribution is complicated due to the interactions CR particles suffer on their way to Earth, and their interactions with X-rays.

CRs can be studied with a variety of methods. Astrochemical methods, as discussed here, provide one opportunity. Specifically, these methods are sensitive to the ionization rate caused by CR interactions. Other methods are summarized by, e.g. \citet{2015ARA&A..53..199G}. It is, for example, possible to directly detect the protons, electrons, and other constituents of the CR sea in particle detectors. Unfortunately, the trajectories of CR particles with energies below a few GeV are heavily influenced by the solar wind. One must correct for this so-called solar modulation if one wishes to study these lower-energy CRs via direct detection. This possibly excludes CR data from \textit{Voyager 1}, which potentially has left the heliosphere. Alternatively, one can explore CRs via indirect methods, i.e., by studying the electromagnetic radiation CRs produce as they propagate through interstellar space. Synchrotron radiation from CRs moving in magnetic fields is one example. CRs also produce $\gamma$~rays when they interact with ISM particles: the collisions produce pions that decay in a variety of ways. The $\gamma$~ray observations allow us to study CRs down to energies $\sim{}1~\rm{}GeV$ \citep[e.g.][]{2014A&A...566A.142Y}.

CRs with energies $\lesssim{}0.1~\rm{}GeV$ are the primary agent responsible for the ionization in the dense sectors of the ISM that are shielded well from UV~radiation \citep[e.g., Fig. 14 of][]{2009A&A...501..619P}. Note that the properties of these CRs are poorly constrained by many of the aforementioned experiments: direct detection experiments and investigations of $\gamma$~rays can only provide reliable statements for energies $\ge{}1~\rm{}GeV$. This means that astrochemical studies that are sensitive to the ionization rate can deliver meaningful constraints on low-energy CRs, but it also means that CR-influenced astrochemistry is badly constrained by other observations, such as those of gamma-rays.

The importance of these CR ionization events for initiating interstellar chemistry means that observations of molecules become useful probes for $\zeta_{\rm CR}$. ISM ion-molecule chemistry begins with the formation of H$_3^+$, which is directly linked to the CR ionization rate as
\begin{eqnarray}
{\rm H}_2 + {\rm CR} 	&\Rightarrow& {\rm H}_2^+ + {\rm e}^{-} \\
{\rm H}_2^+ + {\rm H}_2 	&\Rightarrow& {\rm H}_3^+ + {\rm H}
\end{eqnarray}
H$_3^+$ can then interact with neutral atoms and small molecules to form larger molecules, such as HCO$^+$, OH$^+$ and H$_2$O$^+$, which are thus indirectly linked to the CR ionization rate. For an overview of the ion chemistry in the interstellar medium, we refer the reader to \citet{2008ARAC....1..229S}.

As such, observations of ions and other species are essentially indirect probes of the cosmic-ray ionization through its effects on the interstellar chemistry. By observing and interpreting the abundances of molecules in the ISM we can therefore constrain $\zeta_{\rm CR}$. This can, for example, be done using statistical methods, such as $\chi^2$ minimization for fitting parameters. In the case of a few well-understood molecules with a simple chemistry, it is even possible to estimate the CR ionization rate directly from observed molecular abundances \citep[see, e.g.][]{1998ApJ...499..234C, 2010A&A...521L..10N, 2012ApJ...758...83I, 2015ApJ...800...40I}.

But first we need to get a better understanding of CR-driven chemistry in the ISM by exploring how and which molecules are affected by the CR ionization rate the most. The aim of this paper is therefore to seek better probes that can improve future surveys of the CR ionization rate by studying the distinctive effect that it has on a selection of species often found in large surveys. To develop a first overview here we focus on a --- rather idealized --- situation in the parameter space of cloud structure. We consider molecules in a medium with constant gas and dust temperature at a density of $10^4~\rm{}cm^{-3}$ that develop out of some initial state assumed to be the same for all calculations. Reality is likely to be more intricate. However, our approach reduces the problem to a tangible one, and the calculations are certainly suited to revealing the astrochemical complexity encountered even under the most simple conditions.

In Section~\ref{sec:CRrate} we discuss previous observational measurements. In Section~\ref{sec:model} we present our model and a comparative model of derived measurement techniques. The results of the models are separated into discussions of the general trends of the increasing $\zeta_{\rm CR}$~in Section~\ref{sec:chemsen}, and single species and species pairs as effective probes in Section~\ref{sec:single} and \ref{sec:pairs} respectively. We discuss our conclusions in Section~\ref{sec:conclusions}.

\section{Observational measurements}\label{sec:CRrate}
\begin{figure*}[!htb]
\centering
\includegraphics[width=0.99\textwidth]{fig1.pdf}
\caption{Compilation of observed sources with measured H$_2$ column densities and $\zeta_{\rm CR}$. The symbols specify the type of object in the observations as follows: diffuse clouds ($\blacksquare$), low-mass cores ($\bullet$), and massive protostellar envelopes ($\times$). Data from diffuse clouds come from \citet{2002ApJ...577..221R}, and \citet{2007ApJ...671.1736I, 2015ApJ...800...40I}; low-mass cores are from \citet{1998ApJ...499..234C}, \citet{1998ApJ...503..689W}, \citet{2001Natur.409..159A}, and \citet{2007ApJ...664..956M}; massive protostellar envelopes are from \citet{1996A&A...310..315D}, \citet{2000ApJ...537..283V}, \citet{2000A&A...358L..79V}, \citet{2002A&A...389..446D}, and \citet{2008ApJ...675..405S}. The red squares are observations of low-mass cores by \citet{1998ApJ...499..234C}, the gray boxes are observations of diffuse clouds toward Sagittarius B2 by \citet{2015ApJ...800...40I}, and the gray box shows the range of values derived from the sample of low-mass cores by \citet{1998ApJ...503..689W}. The solid lines are from fits derived by \citet{2009A&A...501..619P} from proton \citep[W98]{1998ApJ...506..329W}, \citep[M02]{2002ApJ...565..280M} and electron \citep[C00, E00]{2000ApJ...537..763S} LIS data. This is an updated version of Figure~15 in \citet{2009A&A...501..619P}.
}
\label{fig:CRobs}
\end{figure*}

The rate of CR ionization events varies depending on the environment and its physical properties. In Figure~\ref{fig:CRobs} we plot CR ionization rates and H$_2$ column densities derived from observations toward diffuse clouds, low-mass cores, and protostellar envelopes. We also include the models derived by \citet{2009A&A...501..619P}, who considered two different determinations of the steady-state local interstellar spectrum (LIS) for CR protons by \citet[][``minimum"; W98]{1998ApJ...506..329W} and \citet[][``maximum"; M02]{2002ApJ...565..280M}, and two electron LISs by \citet{2000ApJ...537..763S}, C00 for their ``conventional" model C and E00 for their steeper (``SE") model. We combine the two proton and electron LIS results in the four lines in Figure~\ref{fig:CRobs}.

Following \citet{1973ApJ...185..505H}, a CR ionization rate of $3\times{}10^{-17}~\rm{}s^{-1}$ is often adopted for dense cores in the solar neighborhood. One should, however, note that quite a range of values for the CR ionization rate has been reported in the literature \citep[e.g.][]{1998ApJ...499..234C, 1998ApJ...503..689W, 2007ApJ...664..956M}. In particular, exploration of the large sample studied by \citet{1998ApJ...499..234C} yields rates in the range $10^{-18}~{\rm{}to}~10^{-16}~\rm{}$ s$^{-1}$. Such estimates are subject to a range of uncertainties - of which some are examined in this paper. Still, Caselli et al. claim that their data are best explained by an actual variation in the CR ionization rate. If so, a variation of $\zeta_{\rm CR}$~by two orders of magnitude in the solar neighborhood is certainly worthy of future investigations.

Many previous studies have sought to quantify the relationship between the CR ionization rate and measurables such as column densities of different ions. In Figure~\ref{fig:CRobs} we plot the results of observations for determining the CR ionization rate in different objects. Atomic and molecular diffuse clouds themselves lie in the range $10^{-16} - 10^{-15}$ s$^{-1}$, while dense molecular clouds and low-mass cores lie in the lower range 5$\times 10^{-18} - 1 \times 10^{-15}$ s$^{-1}$.

\section{Model and measurement techniques}\label{sec:model}
One of the goals of this study is to present our adopted model and then compare it to equations derived for determining the CR ionization rate from observational quantities.

\subsection{Model}
In this study we have utilized the gas-grain chemical model ``ALCHEMIC" developed by \citet{2010A&A...522A..42S}, who also presented a detailed description of the code and its performance. Below we give a brief explanation of the code. A UV photodesorption yield for surface species of 10$^{-3}$ is assumed \citep[see, e.g.][]{2009A&A...504..891O, 2009A&A...496..281O}. The self-shielding of H$_2$ from photodissociation is calculated by Equation 37 with \citet{1996ApJ...468..269D}, assuming a total extinction of 0.5 mag with a total column density $1.1 \times 10^{21}$ cm$^{-2}$ \citep{2009MNRAS.400.2050G}. The shielding of CO by dust grains, H$_2$, and its self-shielding, are calculated using the precomputed table from \citet{1996A&A...311..690L}. We use the chemical network from \citet{2013ApJS..207...27A}, which was updated for the ortho-para chemistry of H$_2$, H$_2^+$ and H$_3^+$ by \citet{2014ApJ...787...44A}. For initial abundances we adopt the ``low metal" initial abundances from \citet{1982ApJS...48..321G}, meaning that the medium begins as half molecular (due to H$_2$ being the dominant species), and completely neutral. We have also updated several tens of photoreaction rates from the original chemical model using the calculations of \citet{2006FaDi..133..231V}.

\begin{figure}[!hbt]
\centering
\includegraphics[width=0.46\textwidth]{fig2.pdf}
\caption{Gas and dust temperature as a function of $\zeta_{\rm CR}$, based on heating and cooling rates calculating using the procedure described in \citet{2001ApJ...557..736G}.
\label{fig:temperature}}
\end{figure}

\begin{deluxetable*}{ll}
\centering
\tablewidth{1.0\textwidth}
\tabletypesize{\small}
\tablecaption{Selection of observationally relevant molecules of primary concern in this paper. CH$_3$CCH is renamed to C$_3$H$_4$ in the adopted chemical network. \label{tab:selected_mols}}
\tablehead{
\colhead{Molecules}							&	\colhead{Reference}
}
\startdata
C, C$^+,$ CO, O												&	\citet{2001ApJ...557..736G} and \citet{2013ApJ...768L..34C}		\\
HNCO, HCN, HCO$^+$, HNC, N$_2$H$^+$, CH$_3$OH, CS, CN, CO		&	\citet{2014ApJ...788....4W}						\\
C$_3$H$_2$, CH$_3$CCH (C$_3$H$_4$), C$_4$H, NH$_2$D, SO			&	\citet{Frau2012}								\\
HC$_3$N, C$_2$H, SiO											&	MALT90 survey; \citet{2013PASA...30...57J}, 			\\
															&	\citet{2011ApJS..197...25F}, and \citet{2013PASA...30...38F}		\\
HOC$^+$														&	\citet{2015MNRAS.446.3842A}		\\
DCO$^+$														&	\citet{1998ApJ...499..234C}		\\
H$_3$O$^+$													&	\citet{2006AA...454L..99V}		\\
\enddata
\end{deluxetable*}

In Table~\ref{tab:selected_mols} we have compiled a list of observationally relevant molecules that we seek to investigate as possible probes. This selection is motivated by a number of studies that are broadly representative of observational investigations of molecules at millimeter wavelengths. Specifically, the line surveys by \citet{2011ApJS..197...25F, 2013PASA...30...38F}, \citet{Frau2012}, \citet{2013PASA...30...57J}, and \citet{2014ApJ...788....4W} give a broad overview of species that are easily detected in molecular clouds. We include additional molecules that are relevant for particular astrophysical reasons. These species are taken from the following studies: \citet{2001ApJ...557..736G} and \citet{2013ApJ...768L..34C}, who investigated cooling via spectral lines; \citet{1998ApJ...499..234C}, who introduced DCO$^+$ as a tool for CR determination; \citet{2015MNRAS.446.3842A}, who highlighted HOC$^+$ as an important ionized molecule; and \citet{2006AA...454L..99V}, who employed H$_3$O$^+$ as a probe of CRs in the Galactic Center region.

Based on Figure~\ref{fig:CRobs} we will investigate CR ionization rates in the range 5$\times 10^{-18}-$1$\times 10^{-15}$ s$^{-1}$ distributed in 25 logarithmically separated steps. Because CRs are heat sources, we include a routine to calculate the CR heating and cooling rates using the procedure described in \citet{2001ApJ...557..736G} to adjust the temperature based on the typical temperature of the modeled object. For these calculations we adopt a dust temperature of 10 K, consider negligible gas-dust coupling, and calculate gas temperature from balancing the heating and cooling rates based on the depletion factor at a density of 1$\times 10^{4}$ cm$^{-3}$. This gives us a improved estimate on the temperature structure of our object. Calculated gas and dust temperatures are shown in Figure~\ref{fig:temperature}.

\subsection{CR estimation techniques}\label{sec:crest}
\begin{figure}[!htb]
\centering
\includegraphics[width=0.48\textwidth]{fig3.pdf}
\caption{Calculated CR ionization rates from relations derived by different studies vs. the actual modeled CR ionization rate. We adopt $\epsilon = 0.07\pm 0.04$ \citep{2012ApJ...758...83I}. The gray dashed line represents a perfect agreement between the CR ionization rate relations and the actual modeled CR ionization rate.}
\label{fig:CRcalc}
\end{figure}

So far, one of the most practiced methods for constraining $\zeta_{\rm CR}$~is using ions and other species as indirect probes by interpreting their abundances based on our understanding of the interstellar chemistry. In Figure~\ref{fig:CRcalc} we plot the calculated versus the modeled CR ionization rate. Equations are based on studies by \citet{1998ApJ...499..234C} for dense clouds (top panel), and \citet{2010A&A...521L..10N} and \citet{2015ApJ...800...40I} for diffuse clouds (bottom panel). The dotted line represents a perfect agreement between the equations and our model. The relation by \citet{1998ApJ...499..234C} fits our model results quite well, within a factor 2--5. We also see changes between 1 and 10 Myr, but the chemistry does not change significantly after 10 Myr.

The equations from \citet{2010A&A...521L..10N} and \citet{2015ApJ...800...40I} have a much larger disagreement with the models for diffuse clouds. But if we exclude the lower end of the CR ionization rate, $\lesssim 10^{-16}$ s$^{-1}$ as CR ionization rates are higher than those in dense clouds, they agree within a factor of 2--5. It appears that there is not much variation already after 1 Myr for diffuse clouds.

\citet{1998ApJ...499..234C} determined the ionization degree and cosmic ionization rate for 24 dark cloud cores based on observations by \citet{1995ApJ...448..207B}. Employing simple steady-state models for deriving HCO$^+$/CO ratios \citep[see, e.g.][]{1979ApJ...234..876W, 1982A&A...107..107G}, they derived the following relation:
\begin{equation}	\label{eq:caselli}
\zeta_{\rm CR}	=	\left[(k_1 + k_2) + \delta\right] n(e^-) \frac{n({\rm HCO}^+)}{n({\rm CO)}} \frac{k_3}{k_4}
\end{equation}
where $\delta$ is the reaction rate for H$_3^+$ (and H$_2$D$^+$) due to reactions with neutral species such as CO and O. \citet{1998ApJ...499..234C} estimated this as $\delta = 6.5\times 10^{-13} /$ f$_D$ cm$^3$ s$^{-1}$, where $f_D$ = [CO$_{\rm gas}$]/$\left([{\rm CO}_{\rm gas}]+[{\rm CO}_{\rm ice}]\right)$ is the depletion factor, i.e. the abundance fraction of gaseous CO over total (gas phase plus ice mantle) molecules. [X] denotes the absolute abundance of species X. The rates $k_i$ of other reactions included are as follows:
\begin{eqnarray}
&k_1&:	{\rm (o/p)\textnormal{-}H}_3^+ 	+	e^-		~~\Rightarrow	{\rm H}_2			+	{\rm H}		\label{eq:1}	\\
&k_2&:	{\rm (o/p)\textnormal{-}H}_3^+ 	+	e^-		~~\Rightarrow	{\rm H} + {\rm H} 	+	{\rm H}	\label{eq:2}	\\
&k_3&:	{\rm HCO}^+			  ~~~+	e^-		~~\Rightarrow	{\rm CO}			+	{\rm H}		\label{eq:3}	\\
&k_4&:	{\rm (o/p)\textnormal{-}H}_3^+	+	{\rm CO}	\Rightarrow	{\rm HCO/HOC}^+	+	{\rm (o/p)\textnormal{-}H}_2	\label{eq:4}
\end{eqnarray}
For the comparison we adopted a TMC 1-like molecular cloud model with $n_{\rm H}~=~10^4$ cm$^{-3}$, $A_{\rm V}$~=~10 magnitudes, $n(e^{-})$ calculated from the models, and compared our model to Equation~\ref{eq:caselli}.

Modeling of dense clouds is easier, as we had high extinctions that block out UV photons and other additional processes, and we are left with CR photons as a dominant process. But some of the results presented here can also be transferred to diffuse clouds, and for comparison we also briefly discuss CR calculations in diffuse clouds. Compared to dark clouds, diffuse clouds have lower extinction values, which leads to higher effective CR ionization rates. Together with the high temperatures, this results in a different chemistry than that in dark clouds. More specifically, it leads to other ions dominating the chemistry. H$_3^+$ is not as abundant because of a high abundance of free electrons, which efficiently react with it and reduce its abundance. While HCO$^+$ is a strong probe for $\zeta_{\rm CR}$~in dark clouds, OH$^+$ and H$_2$O$^+$ are two dominant ions that commonly are used as probes for $\zeta_{\rm CR}$~in diffuse clouds.

\citet{2010A&A...521L..10N} observed OH$^+$ and H$_2$O$^+$ from diffuse clouds along the sightline to the bright continuum source W49N. \citet{2012ApJ...758...83I} observed OH$^+$, H$_2$O$^+$, and H$_3^+$ in diffuse molecular clouds along sightlines near W51 IRS2.

Following these results, \citet{2015ApJ...800...40I} examined observations of OH$^+$, H$_2$O$^+$ and H$_3$O$^+$ in diffuse clouds observed toward 20 sightlines with different Galactocentric radii with bright submillimeter continuum sources. These studies focused on the OH$^+$/H$_2$O$^+$ abundance ratio as a critical probe of the molecular fraction. Assuming that all OH$^+$ is destroyed by reacting with H$_2$ and by dissociative recombination at a rate equal to its formation rate (e.g. steady-state chemistry), they derived an equation for calculating $\zeta_{\rm CR}$:
\begin{equation}	\label{eq:indriolo15}
\epsilon\zeta_{\rm CR}	=	\frac{n({\rm OH}^+)n(e^-)}{n_{\rm H}}  \left[\frac{k_3}{n({\rm OH}^+) / n({\rm H}_2{\rm O}^+) - k_4/k_1} + k_2 \right]
\end{equation}
where $k_j$ are the reaction rates for the following reactions:
\begin{eqnarray}
k_1:	{\rm OH}^+ 		+	{\rm H}_2			&\Rightarrow&	{\rm H}_2{\rm O}^+	+	{\rm H}	\label{eq:5}	\\
k_2:	{\rm OH}^+		+	e^-				&\Rightarrow&	{\rm products}					\label{eq:6}	\\
k_3:	{\rm H}_2{\rm O}^+	+	e^-				&\Rightarrow&	{\rm products}					\label{eq:7}	\\
k_4:	{\rm H}_2{\rm O}^+	+	{\rm H}_2			&\Rightarrow&	{\rm H}_3{\rm O}^+	+	{\rm H}	\label{eq:8}
\end{eqnarray}
and $\epsilon$ is an efficiency factor introduced by \citet{2010A&A...521L..10N} that accounts for the fact that not every CR ionization event results in the net production of an OH$^+$ molecule \citep[e.g. $\epsilon = 0.07\pm0.04$; ][]{2012ApJ...758...83I}. For this comparison we assume a similar diffuse cloud model to \citet{2015ApJ...800...40I} with $n_{\rm H}$~=~35 cm$^{-3}$, $T=100$ K, $n(e^{-}) = 5.25 \times 10^{-3}$ cm$^{-3}$, $\epsilon = 0.07\pm 0.03$ and $A_{\rm V}$~=~1~magnitude. Because of the intense conditions, these environments are often predominantly atomic. Hence, we initiate our models with atomic abundances, including hydrogen.

It is clear that the equation overestimates $\zeta_{\rm CR}$. But this overestimation decreases with time and at higher modeled $\zeta_{\rm CR}$~it even underestimates the rate. It shows the problem with assuming steady-state chemistry.  \citet{2012ApJ...754..105H} argued, for example, that steady-state is achieved on a timescale $\sim{}10^9~{\rm{}yr}/n(H)$, corresponding to $\sim{}30~\rm{}Myr$ at the density of $35~\rm{}cm^{-3}$ adopted here. It is conceivable that gas in the diffuse ISM is subject to relatively constant conditions over long periods of time. In that case estimates following the \citet{2015ApJ...800...40I} formalism do yield correct results. Still, the caveat of steady-state chemistry should be kept in mind. UV photons are contributing significantly to the production of electrons in diffuse clouds, and this is taken into account in our model, but not the equations.

While the two relations reproduce our model results quite well, there are still discrepancies. Our aim is to outline the use of molecular probes of $\zeta_{{\rm CR}}$ that are now routinely accessible with advanced facilities such as the Atacama Pathfinder Experiment (APEX) or the Atacama Large Millimeter/submillimeter Array (ALMA). In the next sections we will review and discuss the chemical species that are the most promising as probes of the CR ionization rate over the full ionization range and chemical ages in dense clouds. The identified list of species might also help with finding possible probes in circumstances where the standard probes are not available.

\section{General trends}
\label{sec:chemsen}
\begin{figure*}[hbt]
\centering
\includegraphics[width=0.49\textwidth]{fig4.pdf}
\caption{The ratio between abundances for ions vs. neutral species is shown in the bottom panel, calculated by adding all species abundances that contain a charge (+/-). The figure shows the same general behavior as the electron abundance. The top panel shows the atomic vs. molecular (right) abundances as a function of $\zeta_{\rm CR}$.
}
\label{fig:ions_and_atoms}
\end{figure*}
We begin by looking at the overall trends in the chemistry to get an idea about the effects an increase in $\zeta_{\rm CR}$~has on the chemistry of molecular clouds. Because our selection of species is small, we have calculated these trends based on the full chemical network, consisting of approximately 1300 species. In Figure~\ref{fig:ions_and_atoms} we look at the ratio of atomic versus molecular abundances (top panel) and the ionization degree of the material (bottom panel) as a function of $\zeta_{\rm CR}$.

The atomic versus molecular abundance ratio in the left panel is calculated as the ratio between the mass-weighted sums of the two groups:
\begin{equation}
\sum_{i} m_{\rm atoms} \times n_{\rm atoms}/\sum_{j} m_{\rm molecules} \times n_{\rm molecules}\nonumber
\end{equation}
Up to 10 kyr the ratio is fairly flat and not affected by the increasing $\zeta_{\rm CR}$. It is not until later that the effects starts to show. At 100 kyr the material has become overall more molecular, with the small exception for the highest $\zeta_{\rm CR}$~$\sim 10^{-15}$ s$^{-1}$ for which molecular dissociation has already begun dominating the chemistry. At 1 Myr the trend from 100 kyr continues, and from here on the molecular dissociation stepwise begins dominating with time, which results in a monotonic increase in the ratio with $\zeta_{\rm CR}$. As such, for old objects $\gtrsim$1 Myr, this could be a very powerful probe. It requires a detailed examination of the abundances of atoms versus molecules, which we leave for a future study.

The effects of molecular dissociation are much clearer when we consider the abundance ratio between ions and neutral species, shown in the right panel of Figure~\ref{fig:ions_and_atoms}. Charged species can carry either a positive (+) or negative (--) charge, and we calculate the mass-weighted ratio as
\begin{equation}
\sum_{i} m_{\rm ions} \times n_{\rm ions}/\sum_{j} m_{\rm neutrals} \times n_{\rm neutrals}\nonumber
\end{equation}
The distribution clearly shows that ions are sensitive to an increase in $\zeta_{\rm CR}$, as we see a shallow but clear trend of the ratio increasing with $\zeta_{\rm CR}$. But it is the large increase at 1 Myr for $\zeta_{\rm CR}$~$\gtrsim 3 \times 10^{-16}$ s$^{-1}$ that is the strongest sign of the molecular dissociation, where the number of atomic ions is greatly increased. Aside from that, we see that the ratios decrease overall with time, meaning that the material is, with time, slowly becoming more neutral: part of the atomic material is reforming neutral molecules. Though the trend increases for old objects at the highest $\zeta_{\rm CR}$~$\sim 10^{-15}$ s$^{-1}$ and the trends are monotonic at every time step, the variance is very small. Again, this should be investigated by future studies.

\begin{figure*}[!bthp]
\centering
\includegraphics[width=0.99\textwidth]{fig5.pdf}
\caption{Abundances for a selection of the most commonly observed molecules as a function of time, plotted for different densities and $\zeta_{\rm CR}$.
}
\label{fig:timedens}
\end{figure*}

We will also look at the effects of an increase in both density and time. Because temperature is directly linked to $\zeta_{\rm CR}$~through the calculated cooling and heating rates, we do not investigate this parameter separately.

In Figure~\ref{fig:timedens} we plot abundances for a variety of commonly observed molecules as a function of time for three different densities (rows; $10^4$, $10^6$ and 10$^8$ cm$^{-3}$) and two different CR ionization rates (columns; $10^{-17}$ s$^{-1}$ and $10^{-15}$ s$^{-1}$).

Increasing the density has the strongest effect on the chemical time scale. In Figure~\ref{fig:timedens} we see the abundances increasing, in some cases monotonically, until they reach a peak value. This peak moves to earlier times with increasing density. After this point, the chemistry becomes more complex. Compared to previously only being dominated by ion--neutral reactions, surface chemistry and neutral--neutral reactions begin to play a significant role. An increase in small ions, in particular atomic ions, also affects the chemical equilibrium values.

With time, often after approximately 1 or 10 Myr, depending on the ionization rate, the system reaches an equilibrium state. The equilibrium state of the species' abundances largely depends on the adsorption of species onto grain surfaces, which becomes more efficient with higher densities and $\zeta_{\rm CR}$. The effect from an increase in $\zeta_{\rm CR}$~is indirect, as it also increases the temperature, and thus the amount of material desorbed into the gas phase for some species, but also increases the amount of ions, which has significant effects on the chemistry.

In comparison, $\zeta_{\rm CR}$~can have very significant influence on the chemistry, in particular on the steady-state abundances. But density has a similar effect between low and high $\zeta_{\rm CR}$. That means that density only competes with time to effect the chemistry, and its effect is much less significant. We conclude that density is not as important as time for the chemical evolution, and in order to simplify the analysis, we exclude it from the study by keeping it constant at $n_{\rm H} = 10^{4}$ cm$^{-3}$.

\section{Individual tracers}\label{sec:single}
Here, we look at the overall trends in abundances for the species listed in Table~\ref{tab:selected_mols}. Species must fulfill a number of conditions to be useful as probes of the CR ionization rate. First, molecules must be sufficiently abundant to be observable; in our case we consider a relative abundance of $10^{-15}$ to be the limit of observability. Second, ideal probes must show a monotonous increase or decrease of their abundances versus $\zeta_{\rm CR}$. Third, these abundance variations as a function of $\zeta_{\rm CR}$~are ideally large so that differences can easily be observed. While the species that we consider in Table~\ref{tab:selected_mols} have been proven to be observable, and hence fulfill the first criterion, we will take into account the two other criteria.

\subsection{Probe score}\label{sec:score}
The usefulness of an individual or pair of species will be discretized to a probe score, ranging between 0 and 1, based on the above criteria. The score is defined by the multiplication of two factors; the fractional range in $\zeta_{\rm CR}$~where the species can be used as a probe, and the logarithm of the maximum abundance variations. By multiplying the two factors, which we have named as the $functional$ and the $variation$ factors, respectively, we calculate the probe score.

The functional factor will be calculated based on the most dominant trend between positive and negative trends. In order to do this, we need to determine trends in the data and as such, need to define what constitutes a significant variation. All CR ionization events will not result in the production of the target species, represented by $\epsilon$ for the case of OH$^+$ in Section~\ref{sec:crest}. We consider a conservative effectiveness of 50\%. This means that for an increase in $\zeta_{\rm CR}$~by one order of magnitude, abundance should increase by at least a factor of 5, and anything less signifies a $plateau$. After plateaus have been identified we use Theil-Sen regression to determine the remaining trends in the distribution. This is a robust regression method from the python package \textsc{scikit-learn} that ignores outliers.

\pdfimageresolution=10
\begin{figure*}[!tb]
\centering
\includegraphics[width=1.00\textwidth]{fig6.pdf}
\caption{Violin plots showing ranges of abundances for essential molecules after 0.01, 0.1, and 1 Myr. Values are normalized to each molecule's median abundance, which better represents the abundance variation between species, and for comparison the median abundance is shown near the bottom. Mean values are shown with a green line and the probe scores are calculated from the different quartiles of the total distribution of probe scores. The green scores represent the top quartiles with scores $\geq 0.59$, the yellow scores represent the second quartiles with scores $> 0.39$, the orange scores represent the third quartile with scores $> 0.20$, the red scores represent any non-zero values, and the gray scores represent a fully plateaued distribution.
}
\label{fig:violinplots}
\end{figure*}

A plateau limits the functional range of a probe, but a repeated switch between positive and negative trends will also have a great impact on how useful a probe is. If it switches once, we get a bow-shaped distribution, and as long as we can clearly distinguish between the positive and negative sides of the distribution, the species is still useful as a probe. However, if the trend changes more than once, it severely reduces how useful the species is as a probe, and in these cases we therefore halve the probe score.

The variation factor in the probe score is defined as the logarithm of the ratio between the maximum and the minimum abundance, $R =$ log$_{10}$~(max[X]/min[X]), for species X. Abundance variations will be restricted, as variations beyond a certain factor will not have a significant impact. In this study we consider this limit to be a factor of 100, based on our observational experience. We still want to be able to separate and rank species that have extremely large abundance variation. For this reason the variation factor will be linear with $\zeta_{\rm CR}$~up to a factor 0.1 below the maximum allowed variance. After that, we adopt a relation $\propto x/(1+x)$, where $x$ is the logarithm of the abundance variation. Finally, the $variation$ factor is normalized.

\subsection{Survey of observable species}
We start with an overview of our selection of species. In Figure~\ref{fig:violinplots} the abundances are shown separately for 0.01, 0.1, and 1 Myr (top to bottom) in so-called ``violin plots". Abundances are shown relative to their median values and for comparison the mean abundance is indicated with a green line. The median values of each species are printed at the bottom of each panel. The gray shapes show the probability density function, a non-parametric estimate of the probability distribution, determining the probability of specific abundances to be found at certain abundance ranges.

The probe scores of individual species are shown at the bottom of each panel. They are color-coded based on the four quartiles of the distribution of calculated probe scores for all species in Table~\ref{tab:selected_mols} and the three investigated time steps. We split calculated probe scores into quartiles, each containing a fourth of the total probe scores. The green probe scores represent the top quartile with values $\geq$0.59, the yellow scores represent the second quartile with scores $\geq$0.39, the orange scores represent the third quartile with scores $\geq$0.20 and the red scores represent with scores >0.0. Cases for which there is no significant variation in the abundances over the complete $\zeta_{\rm CR}$~range are flagged as plateau distributions and are represented in gray with a probing score of 0.

The species in Figure~\ref{fig:violinplots} are arranged such that ions are shown first, followed by neutral molecules, both with an increasing number of atoms. Though ions are strongly connected to $\zeta_{\rm CR}$, their probe scores are telling a different story, with many examples of having low probe scores. No ions show a persistently high score. This is due to a mix of small abundance variations and sensitivity to the increasing electron density that follows the increase in $\zeta_{\rm CR}$. N$_2$H$^+$ and HOC$^+$ both stand out as great probes at times <1 Myr, and to some lesser extent also HCO$^+$, but at 1 Myr C$^+$ is the only useful probe.

Amongst the neutrals, the trends vary a lot, and we find good probe scores for all different types and sizes of species. Amongst the atoms, C stands out as an excellent probe at 1 Myr, just like C$^+$, but at earlier times its probe scores also suffer from small abundance variations. Amongst diatomic species, SO is the sole species that shows promise, and in fact at all three time steps. The triatomic species all have below average scores, but amongst the more complex species we find several probes, and amongst these, HNCO and C$_3$H$_4$ are the most promising.

\subsection{Selected tracers}\label{sec:ind_tracers}
\begin{figure*}[!htb]
\centering
\includegraphics[width=1.00\textwidth]{fig7.pdf}
\caption{Abundance as a function of $\zeta_{CR}$ for differently behaved molecules at times 0.01 (black line), 0.1 (red line), and 1.0 Myr (blue line). The green scores represent the top quartiles with scores $\geq 0.59$, the yellow scores represent the second quartiles with scores $> 0.39$, orange for third quartile with scores $> 0.20$, and the red scores represent any non-zero values.
}
\label{fig:showcase}
\end{figure*}
As such we have identified eight promising probe candidates that we will take a closer look at by dissecting their chemistry and evaluating their fit as probes of $\zeta_{\rm CR}$. In Figure~\ref{fig:showcase} we illustrate variations in abundances for these selected species and in the following section individually discuss their chemistry. In Table~\ref{tab:ind_regions} we summarize the regions where the individual species are useful as probes for $\zeta_{\rm CR}$.

We compare our model results with the observations of the starless core L1498 by \citet{2006A&A...455..577T}, in order to ascertain the accuracy of our numerical models. Tafalla et al. simultaneously observed N$_2$H$^+$, HCO$^+$ and SO from our list of species. We have marked the observed abundances in Figure~\ref{fig:showcase} with $\times$, adopting $\zeta_{\rm CR}$~=~$3\times10^{-16}$ s$^{-1}$ derived by \citet{1998ApJ...499..234C}. The comparison points to a chemical age of $\sim$10 kyr or 1 Myr. These very different ages illustrate the uncertainties involved when only using a small number of species. The latter is closer to the derived lower age limit by \citet{2013A&A...559A..53M} of a few hundred-thousand years. Discrepancies are likely due to Maret et al. adopting the density structure from \citet{2004A&A...416..191T} instead of a single density point as in this paper.

Atomic ionized carbon (C$^+$) does not increase strongly enough at 10 kyr, and at high $\zeta_{\rm CR}$~it ends with a plateau. At 100 kyr molecular dissociation starts to affect the abundances, resulting in a wavy pattern during this transitional period. It is not until $\sim 1$ Myr that this ion becomes a promising probe. But once again, due to molecular dissociation, its abundance variation is approximately five orders of magnitude.

N$_2$H$^+$ is linked to $\zeta_{\rm CR}$~through its formation from H$_3^+$ reacting with N$_2$. At late chemical ages ($\approx 1$ Myr) it slowly reaches a peak abundance at $\zeta_{\rm CR}$ $\sim 10^{-16}$ s$^{-1}$, after which the abundance quickly drops several orders of magnitude due to molecular dissociation. This limits its usefulness as a probe at late times, which we see reflected in its probing score, while at earlier times it is a great probe with monotonic and large increasing trends.

HCO$^+$ is a commonly used probe for $\zeta_{\rm CR}$. But as we see in the second row of Figure~\ref{fig:showcase}, its isomer HOC$^+$ proves to be a much more consistent probe. At earlier times $< 1$ Myr, both HCO$^+$ and HOC$^+$ show a strong increase with $\zeta_{\rm CR}$. It is at 1 Myr that the two ions differ. While HCO$^+$ suffers greatly from molecular dissociation, and at higher $\zeta_{\rm CR}$~there is also an increase in o-H$_2$, which converts HCO$^+$ to HOC$^+$. As such, HCO$^+$ has a plateau until $\zeta_{\rm CR}$~$\sim 3\times 10^{-16}$ s$^{-1}$ when the dissociation quickly drops abundances. Meanwhile HOC$^+$ benefits from a small but monotonic increase in abundance and only suffers from a plateau at $\zeta_{\rm CR}$~$\sim 10^{-15}$ s$^{-1}$. As such, HOC$^+$ is clearly a more capable $\zeta_{\rm CR}$~probe. Note that the abundance of HOC$^+$ is lower than HCO$^+$ by a factor of 10--100 depending on the time and $\zeta_{\rm CR}$. This, of course, makes observations of HOC$^+$ more challenging than observations of HCO$^+$.

Atomic carbon (C) shows a wide range of behaviors over the three time steps. At 10 kyr it shows a slow decrease in abundance, so slow that it is considered a plateau up until $\zeta_{\rm CR}$~$\approx 10^{-16}$ s$^{-1}$. The decrease in the C abundance is much more significant at 100 kyr, dropping approximately three orders of magnitude until $\zeta_{\rm CR}$ $\gtrsim 10^{-16}$ s$^{-1}$, after which molecular dissociation slowly begins to dominate and increases the C abundance. This results in a much higher probe score, but because of the arc-shape, it is a functional probe over a very limited range in $\zeta_{\rm CR}$. At 1 Myr the molecular dissociation dominates the chemistry of atomic carbon, resulting in a monotonic positive trend. Compared to C$^+$, the two are great probes at 1 Myr, but atomic carbon is also a useful probe at 100 kyr.

SO has a clear positive trend at 10 kyr, but at 100 kyr it suffers from a plateau at $\zeta_{\rm CR}$$~\gtrsim 10^{-16}$ s$^{-1}$, again due to molecular dissociation. At 1 Myr this trend also spreads to lower $\zeta_{\rm CR}$, but the abundance is monotonic aside from a brief plateau at low $\zeta_{\rm CR}$~$\lesssim 10^{-17}$ s$^{-1}$. As such, SO is showing promise at all time steps, aside from a restricted functional range at 100 kyr.

HNCO is a very peculiar case. At 10 kyr it is slightly restricted by a small plateau, but at 100 kyr it is restricted to only being useful up to $\zeta_{\rm CR}$~$\sim 3\times 10^{-17}$ s$^{-1}$. The peculiarity arises at 1 Myr, when its abundance drops by almost eight orders of magnitude. This feature alone makes it interesting as a probe, in particular for more distant or diffuse targets. Reactions with H$^+$ and He$^+$ split the molecule into smaller parts, which are not so easy to reform. Considering that uncertainties in observational measurements increase for distant targets, HNCO shows great promise due to its large variations for for chemical ages $\gtrsim 1$ Myr. The large variations means it is not as sensitive to these errors as other probes and we can get more precise estimates of $\zeta_{\rm CR}$.

The final example is C$_3$H$_4$, another molecule primarily formed on the surface from C$_3$ being hydrogenated. At 10 kyr and 100 kyr, we see a sharp increase in the abundance at $\zeta_{\rm CR}$ $\sim 5\times 10^{-17}$ s$^{-1}$ that is most prominent at 10 kyr. This is caused by the sudden increased inflows of carbon and hydrogen atoms on the dust surfaces and by the dissociation of H$_2$ and longer carbon chains C$_{\rm m}$ for m$> 2$. Despite this bump, C$_3$H$_4$ shows an almost monotonic increase at 10 kyr, while at 100 kyr it is much more restricted at $\zeta_{\rm CR}$~$\gtrsim 10^{-16}$ s$^{-1}$ due to reactions with molecular ions such as H$_3$O$^+$, H$_3^+$ and HCO$^+$. Finally, at 1 Myr the molecule shows fluctuations in its abundance, similar to a sinus curve, which is due to destruction from reacting with molecular ions at low $\zeta_{\rm CR}$, while at $\zeta_{\rm CR}$~$\gtrsim 5\times 10^{-17}$ s$^{-1}$ it begins to reform into C$_4$H$_2$ instead thanks to the strong increase in atomic carbon. Compared to HNCO, C$_3$H$_4$ reforms much more efficiently. This is because it reacts with ions produce molecular ions such as C$_3$H$_{\rm m}^+$, with $m \geq 2$, which can quickly reform into C$_3$H$_4$. However, in this case it is a drawback, keeping its abundance steady and the molecule not useful as a probe for older objects $\gtrsim 1$ Myr.

\begin{table}[!tb]\normalsize
\centering
  \begin{tabular}{cccc}
	\hline	\hline\\[-1.4cm]
Species			&	\multicolumn{3}{c}{Probe area}																\\[-0.5cm]
				&	\multicolumn{1}{c}{10 kyr}		&	\multicolumn{1}{c}{100 kyr}	&	\multicolumn{1}{c}{1 Myr}		\\
	\hline\\[-1.5cm]
C$^+$		&	\mediummark	&	\mediummark		&	\cmark		\\[-0.6cm]
N$_2$H$^+$	&	\cmark		&	\peakmark			&	\barriermark	\\[-0.6cm]
HCO$^+$		&	\cmark		&	\cmark			&	\xmark		\\[-0.6cm]
HOC$^+$		&	\cmark		&	\cmark			&	\peakmark		\\[-0.6cm]
C			&	\bottommark	&	\barriermark		&	\cmark		\\[-0.6cm]
SO			&	\peakmark		&	\mediummark		&	\peakmark		\\[-0.6cm]
HNCO		&	\mediummark	&	\xmark			&	\peakmark		\\[-0.6cm]
C$_3$H$_4$	&	\cmark		&	\mediummark		&	\xmark		\\[0.0cm]
	\hline

  \end{tabular}
  \caption{Listing of the regions where selected individual species show the most promise as probes of $\zeta_{\rm CR}$. The color-coding specifies how restricted the functional range of the probe is: none (green), small (yellow), moderate (orange), and severe (red). The symbols specify the nature of the abundance variation: ticks ($\checkmark$) indicate only one monotonic trend, tildes ($\sim$) signify some level of restriction, and bars ($\mid$) denote a symmetric arc-shaped distribution centered near $\sim 10^{-16}$ s$^{-1}$.
  \label{tab:ind_regions}}
\end{table}

\section{Species pairs}\label{sec:pairs}
\begin{table*}[!htb]\scriptsize
 \centering
\begin{tabular}{lclclc}
\\	\hline	\hline\\[-0.7cm]
Species pair	&	Scores 	& Species pair	&	Scores		& Species pair	&	Scores					\\
\hline\\[-0.35cm]

\raisebox{\height-3px}{N$_2$H$^+$/C$_4$H}		&\greenscore{0.97}   \greenscore{0.82}   \greenscore{0.98}&
\raisebox{\height-3px}{H$_3$O$^+$/C}			&\greenscore{0.70}   \yellowscore{0.63}  \greenscore{0.99}&
\raisebox{\height-3px}{HC$_3$N/CH$_3$OH}		&\greenscore{0.82}   \greenscore{0.67}   \yellowscore{0.63}  \\

\raisebox{\height-3px}{N$_2$H$^+$/C$_2$H}		&\greenscore{0.97}   \greenscore{0.70}   \greenscore{0.98}&
\raisebox{\height-3px}{C$_2$H/HNCO}			&\greenscore{0.98}   \orangescore{0.33}  \greenscore{0.99}&
\raisebox{\height-3px}{C/NH$_2$D}				&\greenscore{0.77}   \yellowscore{0.63}  \greenscore{0.71}   \\

\raisebox{\height-3px}{N$_2$H$^+$/C}		    	&\greenscore{0.98}   \yellowscore{0.63}  \greenscore{0.99}&
\raisebox{\height-3px}{N$_2$H$^+$/C$_3$H$_2$}	&\greenscore{0.98}   \greenscore{0.82}   \orangescore{0.50}&
\raisebox{\height-3px}{SO/C$_4$H}				&\orangescore{0.33}  \greenscore{0.78}   \greenscore{0.99}   \\

\raisebox{\height-3px}{HCO$^+$/C}				&\greenscore{0.97}   \yellowscore{0.63}  \greenscore{0.98}&
\raisebox{\height-3px}{C/CH$_3$OH}			&\greenscore{0.71}   \yellowscore{0.59}  \greenscore{0.99}&
\raisebox{\height-3px}{C$_4$H/C$_3$H$_4$}		&\greenscore{0.78}   \greenscore{0.74}   \yellowscore{0.55}  \\

\raisebox{\height-3px}{C/C$_3$H$_4$}			&\greenscore{0.98}   \yellowscore{0.59}  \greenscore{0.90}&
\raisebox{\height-3px}{H$_3$O$^+$/HNCO}		&\greenscore{0.98}   \yellowscore{0.59}  \greenscore{0.71}&
\raisebox{\height-3px}{HNCO/C$_4$H}			&\greenscore{0.98}   \redscore{0.29}     \greenscore{0.79}   \\

\raisebox{\height-3px}{HOC$^+$/O}				&\greenscore{0.97}   \greenscore{0.97}   \orangescore{0.52}&
\raisebox{\height-3px}{N$_2$H$^+$/HC$_3$N}		&\greenscore{0.98}   \greenscore{0.71}   \yellowscore{0.59}&
\raisebox{\height-3px}{C/CN}					&\greenscore{0.73}   \greenscore{0.70}   \yellowscore{0.62}  \\

\raisebox{\height-3px}{CN/HNCO}				&\greenscore{0.98}   \orangescore{0.41}  \greenscore{0.99}&
\raisebox{\height-3px}{N$_2$H$^+$/O}			&\greenscore{0.98}   \greenscore{0.74}   \yellowscore{0.55}&
\raisebox{\height-3px}{HNCO/CH$_3$OH}		&\greenscore{0.99}   \orangescore{0.39}  \greenscore{0.67}   \\

\raisebox{\height-3px}{HOC$^+$/HNCO}			&\greenscore{0.98}   \greenscore{0.67}   \greenscore{0.71}&
\raisebox{\height-3px}{N$_2$H$^+$/CS}			&\greenscore{0.98}   \greenscore{0.67}   \yellowscore{0.62}&
\raisebox{\height-3px}{HOC$^+$/CS}			&\greenscore{0.97}   \greenscore{0.86}   \redscore{0.20}     \\

\raisebox{\height-3px}{N$_2$H$^+$/HNCO}		&\greenscore{0.99}   \greenscore{0.71}   \greenscore{0.67}&
\raisebox{\height-3px}{SO/HC$_3$N}			&\greenscore{0.97}   \greenscore{0.67}   \yellowscore{0.63}&
\raisebox{\height-3px}{C$^+$/N$_2$H$^+$}		&\greenscore{0.78}   \yellowscore{0.58}  \greenscore{0.67}   \\

\raisebox{\height-3px}{HCO$^+$/HNCO}			&\greenscore{0.98}   \yellowscore{0.59}  \greenscore{0.79}&
\raisebox{\height-3px}{HCO$^+$/HC$_3$N}		&\greenscore{0.97}   \greenscore{0.70}   \yellowscore{0.59}&
\raisebox{\height-3px}{H$_3$O$^+$/HC$_3$N}		&\greenscore{0.73}   \greenscore{0.70}   \yellowscore{0.59}  \\

\raisebox{\height-3px}{C/CO}					&\greenscore{0.77}   \yellowscore{0.59}  \greenscore{0.98}&
\raisebox{\height-3px}{DCO$^+$/N$_2$H$^+$}		&\greenscore{0.97}   \greenscore{0.97}   \orangescore{0.32}&
\raisebox{\height-3px}{C$^+$/HNCO}			&\greenscore{0.98}   \orangescore{0.31}  \greenscore{0.71}   \\

\raisebox{\height-3px}{HOC$^+$/C}				&\greenscore{0.97}   \yellowscore{0.63}  \greenscore{0.74}&
\raisebox{\height-3px}{NH$_2$D/HC$_3$N}		&\yellowscore{0.66}  \greenscore{0.70}   \greenscore{0.82}&
\raisebox{\height-3px}{C$^+$/O}				&\redscore{0.28}     \greenscore{0.74}   \greenscore{0.98}   \\

\raisebox{\height-3px}{N$_2$H$^+$/CN}			&\greenscore{0.97}   \yellowscore{0.58}  \greenscore{0.78}&
\raisebox{\height-3px}{HOC$^+$/HC$_3$N}		&\greenscore{0.89}   \greenscore{0.70}   \yellowscore{0.55}&
\raisebox{\height-3px}{HNCO/C$_3$H$_2$}		&\greenscore{0.90}   \orangescore{0.35}  \greenscore{0.71}   \\

\raisebox{\height-3px}{N$_2$H$^+$/SiO}			&\greenscore{0.97}   \greenscore{0.77}   \yellowscore{0.59}&
\raisebox{\height-3px}{CO/HNCO}				&\greenscore{0.98}   \orangescore{0.43}  \greenscore{0.71}&
\raisebox{\height-3px}{HCO$^+$/O}				&\greenscore{0.78}   \greenscore{0.70}   \redscore{0.27}     \\

\raisebox{\height-3px}{C$_2$H/HNCO}			&\greenscore{0.98}   \orangescore{0.33}  \greenscore{0.99}&
\raisebox{\height-3px}{C/NH$_2$D}				&\greenscore{0.77}   \yellowscore{0.63}  \greenscore{0.71}&               &   \\
\hline
\end{tabular}
\caption{Listing of species pairs in this study that show, in at least two out of the three time steps, a high probing score corresponding to the top quartile of the total distribution. The species pairs are sorted by their mean probing score. The green scores represent the top quartiles with scores $\geq$ 0.66, the yellow scores represent the second quartiles with scores $\geq$ 0.53, the orange scores represent the third quartile with scores $\geq$ 0.31, and the red scores represent any non-zero values. \label{tab:ProbingScore_MolPairs}}
\end{table*}

If we look at pairs of species as probes, it is possible that they can remove restrictions or troublesome behaviors that individual species might have. Because forming pairs based on the selected species in Table~\ref{tab:selected_mols} will create a large number of pairs, we will focus our discussion here on the species pairs with probe scores from the top quartile (scores $\geq 0.66$) in at least two of the time steps. These are listed in Table~\ref{tab:ProbingScore_MolPairs}, sorted by their mean score. From the probe scores we can immediately see that the species pairs perform much better than than the individual species. Many of these pairs have their lowest score at 100 kyr, but there are also many examples of species that have their lowest probe score at 1 Myr. Only a few exceptions have problems at 10 kyr: NH$_2$D/HC$_3$N, SO/C$_4$H and C$^+$/O, but they perform much better at the other time steps.

From the more than 200 species pairs generated, only 44 have at least 2 green probe scores amongst the 3 time steps. Not surprisingly, the majority of these pairs include an ion (22/44). The most commonly listed ion is N$_2$H$^+$ (12/44), which follows from it being one of the most promising individual probes. After this, HCO$^+$ and HOC$^+$ (4/44 and 5/44, respectively) are significantly less common. Amongst the neutrals, HNCO (12/44) is most common, mostly owing to its large abundance variation. It is closely followed by C (8/44) and HC$_3$N (6/44). With the exception of HC$_3$N, these belongs to the best performing individual species that we identified in Section~\ref{sec:ind_tracers}.

As an individual tracer, the mean score of HC$_3$N is pulled down because it is not affected by the increasing $\zeta_{\rm CR}$~at 10 kyr. Otherwise HC$_3$N performs well with green scores at other time steps. When paired with other species that are strongly affected by $\zeta_{\rm CR}$~at 10 kyr, we get a much more promising probe.

Looking at the size of the species pairs, it appears that small differences of 1 $-$ 2 atoms result in the best probes. Looking at differences in atomic weight between the two species, there is a grouping around 13$-$17 in atomic mass, identified as the difference between one heavier element (C, N, O), and possibly also a lighter element (H, D). These small differences suggest that the formation process for either partner of a species pair should have a length difference of one, or at most two, steps. However, the two individual species in the pairs often are formed from different formation pathways. The pairs N$_2$H$^+$/C$_4$H and N$_2$H$^+$/C$_2$H, are excellent examples of this, where one species belongs to nitrogen chemistry, and the other to carbon chemistry. In short: similarity is preferential, but they should not be too similar.

\begin{figure*}[!tb]
\centering
\includegraphics[width=1.00\textwidth]{fig8.pdf}
\caption{Abundance as a function of $\zeta_{CR}$ for differently behaving molecules at times 0.01 (black line), 0.1 (red line) and 1.0 Myr (blue line). Green scores belong to the top quartiles with a score $\geq 0.66$, yellow for the second quartiles with scores $> 0.53$, orange for third quartile with scores $> 0.31$, and red for any non-zero values.
}
\label{fig:showcasePairs}
\end{figure*}

In Figure~\ref{fig:showcasePairs} we plot the abundances of the top 10 scoring species pairs from Table~\ref{tab:ProbingScore_MolPairs}. All of these have a clear monotonic trend at 10 kyr, and the difference between these is their behavior at later times. Most of them have their lowest probe score at 100 kyr, an issue that it shares also with the individual probes. Only four pairs have green scores in all three time steps: N$_2$H$^+$/C$_4$H, N$_2$H$^+$/C$_2$H, HOC$^+$/HNCO, and N$_2$H$^+$/HNCO.

The two topmost pairs N$_2$H$^+$/C$_4$H and N$_2$H$^+$/C$_2$H show great promise as probes at all three time steps. Their greatest limitation is still at 100 kyr at $\zeta_{\rm CR}$~$\gtrsim 10^{-16}$ s$^{-1}$, meaning they are still great probes for more than half the $\zeta_{\rm CR}$~range. The other two fully green pairs HOC$^+$/HNCO and N$_2$H$^+$/HNCO both have steady monotonic increases at 10 kyr, but at later times there are some plateaus that affect the functional range, and limit the probe scores. This does not change the fact that also these are very capable $\zeta_{\rm CR}$~probes.

One particular species pair does not have its lowest probe score at 100 kyr: HOC$^+$/O. It is limited to $\zeta_{\rm CR}$~$\lesssim 2\times 10^{-16}$ s$^{-1}$ and along with a limited functional range, it receives a low score at 1 Myr. N$_2$H$^+$/HNCO also has its lowest scores at 1 Myr. But it produces high probe scores for all time steps, only limited in functional range by plateaus.

The remaining pairs are limited by arc-shaped distributions or extensive plateaus at 100 kyr, and either have a monotonic trend, or small limitations by plateaus or an arc-shaped distribution skewed toward the high end of the $\zeta_{\rm CR}$~range. Even with these limitations, they are capable as probes, as long as one knows enough about the targets to avoid the problematic time scales and areas in the $\zeta_{\rm CR}$~range.

We can clearly see that there are promising probes amongst these species pairs, and in Table~\ref{tab:pairs_regions} we list a summary of how well the most promising species pairs perform. Given that our species selection in Table~\ref{tab:selected_mols} is largely driven by observations, most of the abundance ratios listed in Table 4 can be observed using (sub)millimeter--wavelength telescopes. Species like C$_4$H, C$_3$H$_2$, and HOC$^+$ might require significant integration times, but they are generally observable. The situation is different for ratios involving atoms, though. Observations of C at 492~GHz from the ground are only possible in exceptionally high and dry sites.

High-spectral resolution observations of the ground-state fine structure of neutral atomic oxygen at 63 $\mu$m wavelength (4.7 THz) are now routinely possible with the German Receiver for Astronomy at Terahertz Frequencies \citep[GREAT;]{Risacher2016} on board the Stratospheric Observatory for Infrared Astronomy (SOFIA). The recent SOFIA observations cover this line in the dense \citep{Leurini2015} and diffuse ISM \citep{Wiesemeyer2016}.

\begin{table}[!tb]\small
\centering
  \begin{tabular}{cccc}
	\hline	\hline\\[-1.2cm]
Species			&	\multicolumn{3}{c}{Probe area}																\\[-0.4cm]
				&	\multicolumn{1}{c}{10 kyr}		&	\multicolumn{1}{c}{100 kyr}	&	\multicolumn{1}{c}{1 Myr}		\\
\hline\\[-1.2cm]
N$_2$H$^+$/C$_4$H	&	\cmark		&	\peakmark		&	\peakmark		\\[-0.45cm]
N$_2$H$^+$/C$_2$H	&	\cmark		&	\peakmark		&	\cmark		\\[-0.45cm]
N$_2$H$^+$/C			&	\cmark		&	\mediummark	&	\cmark		\\[-0.45cm]
HCO$^+$/C			&	\cmark		&	\mediummark	&	\cmark		\\[-0.45cm]
C/CH$_3$OH			&	\xmark		&	\barriermark	&	\cmark		\\[-0.45cm]
HNCO/C$_4$H			&	\peakmark		&	\xmark		&	\peakmark		\\[-0.45cm]
C/CO				&	\cmark		&	\barriermark	&	\cmark		\\[-0.45cm]
HOC$^+$/	O			&	\cmark		&	\cmark		&	\barriermark	\\[-0.45cm]
N$_2$H$^+$/C$_3$H$_2$&	\cmark		&	\cmark		&	\bottommark	\\[-0.45cm]
HOC$^+$/HNCO		&	\cmark		&	\bottommark	&	\mediummark	\\[0.05cm]
	\hline
  \end{tabular}
  \caption{Listing of the regions of the most promising species pairs based on their average probe scores. The color-coding specifies how restricted the functional range of the probe is: no (green), small (yellow), moderate (orange), and severe (red). The symbols specify the nature of the abundance variation: ticks ($\checkmark$) indicate only one monotonic trend, tildes ($\sim$) signify some level of restriction, and bars ($\mid$) represent an arc-shaped distribution.
\label{tab:pairs_regions}}
\end{table}

\section{Conclusions}\label{sec:conclusions}
We have looked at the potential of individual and pairs of species as probes for $\zeta_{\rm CR}$~in dense clouds. The study is limited to species commonly observed in large-scale surveys and for $\zeta_{\rm CR}$~=~$5\times 10^{-18} - 1\times10^{-15}$~s$^{-1}$ at the time steps 0.01, 0.1, and 1.0 Myr. Our study is a pilot intended to be expanded to include a larger sample of species to prepare for the new generation of telescopes and future surveys.

Ions are strongly linked to an increase in $\zeta_{\rm CR}$, but molecular ions suffer from molecular dissociation at high $\zeta_{\rm CR}$~$\gtrsim 10^{-16}$ s$^{-1}$ and 1~Myr. This means that primarily atoms are increasing in abundance beyond this point, and as we look at later time steps, the molecular dissociation is dominating at even lower $\zeta_{\rm CR}$. Atomic ions continuously increase with $\zeta_{\rm CR}$, and even more so when the molecular dissociation is dominating. Because the abundance of some atomic ions, in particular H$^+$, C$^+$, He$^+$, as well as those of some abundant molecular ions (e.g. H$_3^+$, HCO$^+$, H$_3$O$^+$), are very reactive, the atomic/molecular as well as ion/neutral ratios will affect the chemistry, and the former in particular could possibly also be used as a probe.

The probe candidates show a range of behaviors depending on their chemistry and in many cases it is the complexity of the species that determines how sensitive they will be to $\zeta_{\rm CR}$. It controls the abundances of atomic and molecular ions as well as electrons, which are the driving components of the destructive pathways. Large, complex molecules with long formation pathways will decrease or even dilute the effects of the steadily increasing $\zeta_{\rm CR}$, while abundances are low because reforming them takes a long time.

In order to infer how great an individual or pair of species can probe $\zeta_{\rm CR}$, we identify different trends in the abundance variations and use them to calculate a probe score. It is based on the multiplication of two factors: one relating to the $functional$ range of the probe, as in how much of the $\zeta_{\rm CR}$~range it can be used as a probe, and one factor relating to the magnitude of abundance $variation$ that the species experience over the studied $\zeta_{\rm CR}$~range. We find that all probe candidates investigated in this study have limitations. That is, none of the individual or pairs of species are perfect probes for the complete investigated $\zeta_{\rm CR}$~range and at all three time steps, but a few come very close with only small limitations.

Amongst individual species, the ions N$_2$H$^+$, HCO$^+$ and HOC$^+$ are the most capable probes. HNCO is a particularly interesting molecule, as it shows an incredibly large range of abundance variation at 1 Myr of almost eight orders of magnitude. This sensitivity is caused by its formation being slow and largely associated with surface chemistry. This may make it a useful probe for more distant targets, as it will not be as sensitive to large errors that can be expected for distant objects.

Species pairs show more promise. Most of them show a monotonic trend with an increasing $\zeta_{\rm CR}$~at 10 kyr and 1 Myr, while many suffer from restrictions during the transitional period at 100 kyr, where many trends are reversed as molecular dissociation begins to affect the chemistry.

Amongst the pairs, there are a few that stand out. N$_2$H$^+$/C$_4$H only shows restrictions at 100 kyr for high $\zeta_{\rm CR}$~$\gtrsim 3\times10^{-16}$ s$^{-1}$ and at 1 Myr for low $\zeta_{\rm CR}$~$\lesssim 8\times 10^{-18}$ s$^{-1}$. N$_2$H$^+$/C$_2$H on the other hand has no restrictions at 1 Myr, but is more limited at 100 kyr to $\zeta_{\rm CR}$~$\lesssim 10^{-16}$ s$^{-1}$. N$_2$H$^+$/C$_2$H, however, on the other hand has no restriction at 1 Myr, but a larger restriction at 100 kyr due to the peak of the arc being shifted to lower $\zeta_{\rm CR}$.

Many species pairs are restricted or not very useful as probes at 100 kyr due to low variations or the trends not being monotonic. But there is an equal number of species pairs that have their lowest probe score at 1 Myr. However, the highest scoring species pairs are almost exclusively belong to the former type.

A number of pairs with HNCO as a partner have the very particular property that their abundance varies by almost eight orders of magnitude at 1 Myr. This can be particularly useful in studies of distant targets, where larger abundance variations could improve the accuracy of the estimated $\zeta_{\rm CR}$.

We have summarized the functional ranges of individual species and species pairs, so that future surveys and observations can target the right probes for the right environments. While this study focused on dense clouds, at least some of these probes are likely also applicable in diffuse clouds and other astrochemical environments. This can be investigated in a future study, and the current one could also be extended to include more species to prepare for the next generation of observational facilities.

\acknowledgments
This research made use of NASA's Astrophysics Data System.

\software{ALCHEMIC \citep{2010A&A...522A..42S}}

redpajama_set_name: RedPajamaArXiv


This paper investigates the relative small sample performance of several robust unit root tests by means of a simulation study. It is confirmed that the traditional least-squares based Dickey-Fuller test has substantially lower power than several robust alternatives if the error distribution is fat-tailed while its power gain is small at the normal model. Particularly good results are achieved by a quasi-maximum likelihood test. However, all robust tests under consideration exhibit severe size distortions if the disturbances follow a skewed distribution. Moreover, under additive outliers, robust tests fail to produce stable sizes and good power properties. Consequently, the value of using robust unit root tests depends heavily of the type of nonnormality at hand.


Thank you so much for considering donating, we understand that money can be tight in today's economy. If you reconsider at a later date, we would love to hear from you. Thanks again, and have a fantastic day.


The Place to forget everything!!!
Constipation has become too normal these days, while some of you consider it as a routine thing. I know we all are at blame for our modern lifestyle and the irregular meal timings has resulted in the rise of the constipation cases. Some of the known reasons include eating junk food, smoking, alcohol dependency, and even overeating.
You may have to cut down on all the greasy and cheesy foods right now! If you have started a new weight-loss regime, then make sure you keep a close check on what's going inside your stomach. One of the common reasons for constipation is unhealthy food habits. Even too much of the caffeine is not recommended.
You read it, baking soda will defuse the acid inside the stomach and help the food to pass out the body quickly. For the usage, take 1 teaspoon of baking soda, and 1/4 cup of warm water. Mix both of these well, and drink it.
This one's the coolest option, but something we all like to skip out – exercise. It's the best solution out of all for pinning out constipation in one go. Jogging, running, bicycling or any form of physical exertion keeps a check on the condition of the bowel movement.
This is for those who have IBS (Irritable Bowel Syndrome), you can follow the low FODMAP diet. In this type of diet, you need to cut down or limit the intake of foods with high FODMAP value. FODMAP stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols. You will be advised to limit some foods for a period of time, which will let you know the main culprit behind the bowel troubles.
Also, kindly note here – just following the low FODMAP won't be enough for IBS condition.


Valentine's Day was the launch pad for the latest consumer campaign targeting unfair insurance tactics with the catchcry "show a little love".
Against a backdrop of throbbing hearts, the Consumer Action Law Centre (CALC) yesterday launched a "dating video" on fairinsurance.com.au, calling on insurers to dump unfair policies.
Australians who believe their insurance claims have been unfairly denied and would like redress are invited to submit their experiences to CALC.
The advocacy group is pushing for insurers to not be exempt from unfair contract terms laws with which other sectors must comply. The organisation yesterday also released a report titled DENIED, which it says details how "shockingly" insurance companies treat some policy-holders.
Insurers are being asked to consider if policy clauses go too far in their favour and whether some of them cause bigger headaches than is warranted.
Meanwhile, the campaign features three actors who humorously discuss how their hearts were broken by their "love interests", which are spoofs of actual insurance companies.
In a short video, a woman tells of once dating a royal (RACV) whose tastes were too expensive; a man says his ex, Amy (AAMI), left him out in the cold when he was most vulnerable; and another recounts how he was dropped by the love of his life, Ally (Allianz), over a pre-existing medical condition.
Tongue firmly in cheek, CALC Chief Executive Gerard Brody said yesterday that even though insurance companies had a bad reputation, he thought their hearts were in the right place".
"So today, for Valentine's Day, we're reaching out to the CEOs of all the major insurance companies to show us some love," he said.
While acknowledging that the Federal Government wanted the unfair terms laws extended to insurers, Mr Brody said "the industry could, and should, act now".
"Many people lose out on their insurance because of unfair contract terms. And insurers are facing a big trust problem with Australians," he said.
"People are getting huge shocks when their insurance claims are denied and yet insurers are the only industry who can legally include unfair contract terms in their contracts. Insurers should apply a fairness test to all terms in their contracts now.
CALC said "it appeared to be very difficult for an individual to get a good result without engaging a lawyer" when they contested an insurer's decision.
"A fair contracts regime for insurance is overdue. If insurers stick to the same rules as everyone else, it will even the playing field and give Australians a better chance of a fair outcome when they need it most," the organisation said.
Each time YourLifeChoices publishes an article about insurance companies' poor treatment of policy-holders, we receive dozens of responses from members who have been conned into buying cover that falls short of expectations.
No doubt the Financial Ombudsman Service (FOS), who is supposed to mediate insurance disputes, hears many similar stories each year. In fact, in its latest annual review it reported that complaints about general insurance had surged 26 per cent to 8100.
If, from a small population such as Australia's, more than 8000 citizens a year feel they have been wronged by the very companies they pay to take care of them when the chips are down, then there is something very broken with the system.
The Consumer Action Law Centre's (CALC) call out to the sector to be the "bigger person" and lift its own game is noble, but is it enough?
The advocacy group should be applauded for shining a light on the discrepancy that exempts insurers from laws on unfair contract terms.
And CALC's gimmicky campaign off the back of Valentine's Day certainly was eye-catching. But I won't be waiting around expecting insurers to become introspective about whether making outrageous profits is wrong.
Let's hope that the Government acts sooner rather than later to implement reforms to the sector as it proposes. And at the very least, the Royal Commission into the Banking and Financial Services sector also ought to use its wide powers to make insurers explain how their policies are fair when roughly one in three claims are rejected.
Yesterday, CALC senior policy officer Susan Quinn told YourLifeChoices the insurance sector was not living up to community expectations.
"Even if the insurers are not breaking the law, to us it is clear that the law has to change," Ms Quinn said.
A starting point would be to force insurers to abide by the same rules other sectors do and not write unfair contract terms which put the interests of consumers way below those of the company.
"In Australia today, protections for people with insurance are weak and hard to access," says CALC. This must change soon.
Has your claim ever been rejected by an insurer? Do you think it is worthwhile buying insurance cover? Have you ever been delighted by exceptional service from an insurer?
The evidence is clear. Insurance companies a very well supported on the ASX because of their high yields. Obviously the claims departments are not in sync with their actuaries.
It is objectionable when insurance companies use their bottomless bank accounts to steamroll people who have a GENUINE claim. This is where governments should be legislating but sadly governments in the western world are controlled by business. So the little person often gets done and the only way to get justice is using the media if it has interest in your story.
ABout time governments got out of bed with insurance companies and did what they were elected to do: work for the citizens of the country.
Oh my pet hate .The government wont do anything .We lost all in the 2011 floods .Bill Shorten came to Ipswich giving us promisez never kept.I sent an email to him NO REPLY. I ring arond every yr. To obtain quotes. .. some are $6,000.00 different some even more. We are paying $3,500.00 a yr on the pension, Talking to many pensioner 1 lady said 1 company wanted $12.000.00 to insure hers she is uninsured as many other pensioners. All the monies that were donated the government here took in interest for their own means a disgrace.
We my first husbane passed away at 29yrs.old The insurance company tried sssooooo many ways to get out off paying I had a 6yr old 4yr.old & a 4month old baby at the time What they put me through was just terrible.
SO MANY OTHER PEOPLE HAVE TOLD US SOME DISGRACEFUL STORIES. At a meeting in 2011 the insurance council head came he sat there for about 30min. got up (yes people were angry) what did he do after a few words he walked out never to return to follow meetings. These people Bill Shorten ,the head of insurances & others are paid the big bucks to sit on their throwns but when the crunch comes do thay do the right thing........INSURANCE IS A DAMED IF YOU DO & DAMED IF YOU DON'T THEY HOLD US TO RANSOM.
Don't blame Shorten and the ALP. Blame Turdball and his Lieberals. The insurance-industry scumbags are his mates, after all.
Don't jump to nasty conclusions, Raphael. Many areas that flooded were classified by councils as ''flood free'' before the 2011 disaster. I know of many homeowners who didn't take flood cover simply because they were advised their area would not flood, and it had not previously. Others were alarmed that insurers relied unfairly on dubious exclusion clauses to escape liability when they had a moral and ethical obligation to pay.
I haven't yet been rejected, but I've hardly ever had to make a claim in any case.
I do believe however, that the clause in most insurance policies which stipulates the first so many hundred dollars of any claim is to be paid for by the insured, coupled with the ubiquitous no-claim bonus, should be scrapped. It is simply an unfair money making ploy for insurers, which allows them to cop out of having to pay out for a great many legitimate, but smaller claims, which might be presented.
In effect, by not paying out on these smaller claims, this increases the profit margin for insurers by several billion dollars every year.
Every time someone complains about an insurance claim the response is along the lines of; "You should have read the policy." When solicitors trained in the skill of reading legal documents cannot agree on what a policy actually covers, what chance does the average person have. Has the argument been settled yet on what constitutes floodwaters and run-off water?
Insurance (a form of gambling) is one of the main scams around. There needs to be a Royal Commission into this industry sector: they are a pack of mongrels.
Its not compulsory to have insurances it always a just in case scenario. If you dont like whats being offered or how you are being treated and so on, change companies. The only way they will ever change is in response to mass consumer demand. There are many great posters on this site who could be asked to whip us mass consumer demand so they have no choice but to respond.
If only it were that simple, Ted, but sadly people often don't find out how bad an insurer is until that rare crisis happens - and then it's too late.
Some superannuation policies also offer TPD (Total Permanent Disability) and IP (Income protection) cover, which at first glance seems complimentary BUT it is far from it. With the IP component only contracted hours are covered. An employer may offer a contract of 20hrs/wk where actual worked hrs maybe 40+. The insurer will often only pay the contracted hrs (Check the fine print). As for the TPD, the initial cover is small often around $10-20K and when younger it may seem adequate. Hidden in the fine print is how this cover actually works: The balance of your superannuation fund is deducted from your payout. So let's say you have $20k of cover and you pay the annual premium for that cover, which is deducted from your super account monthly, which is hardly noticed. We all hope that it's never needed to be claimed but on the off chance that it is say in 20 years time you find that your superannuation contributions balance that you and your employer have been making over the years are actually deducted from your insurance payout figure. The result is that if you have $100k in super with $20k of insurance you will only receive $100k and not the $120K.
Another example is my husband increased his cover to cover our home mortgage "Just in case something happens..." Well, something did happen and he needed to claim and from here the dramas started. With the IP they 'tried' to say 'contracted hrs only' when in fact the policy stated 80% of pre injury income and not contracted hrs. Pre injury income INCLUDED overtime, as overtime was regular and expected by his employer it was part of his regular income. When he queried this with the insurer he was blatantly told "..You are getting what you are getting and that's all you are going to get..." He contacted the super company who sold the policy and eventually the insurer relented and begrudgingly paid the 80%.
Now my husbands intent was to return to work ASAP, which he did, part time, BUT he returned too soon and his condition worsened. He was then told by the Dr's that he would not be able to return to work, so reluctantly he applied for the TPD component of his policy. The insurer made this whole process so demeaning and convoluted, they wanted each and every piece of paperwork from every dr, every specialist and every hospital my husband had ever visited. Every page had to be signed by the relevant dr and each page needed to be certified by a JP. As if the stress of his condition was not enough, these companies had to add to it. If one page was not signed, it was returned. If a single report was missing the claim was rejected. Every obstacle possible was put in the way so as to not pay the claim. In the end my husband got a lawyer on a 'no win, no fee' basis. This was one of the best things he could have done, they dealt with it ALL. He had to attend medical assessment appointments with the insurers dr's but otherwise the lawyer managed it all. Then after another 12months the lawyer called "WE WON".
WON? well, we got the insurer to payout then we had the lawyers fees, then the tax AND the payout figure was less the balance of his super account.
They may offer 'discounted rates', they may offer 'Partnership discounts', even membership assistance programs. DO NOT DO IT. It has cost us thousands in dollars not to mention the stresses, mental anguish and unfathomable frustration in dealing with these mongrels. If you or I ran our business in such a manner we would be charged with a crime.
Someone else here (Elephants) wants to blame Bill Shorten. But the Liberals are all for big business and you can't get much bigger than the insurers. I wrote to Malcolm Turdball expressing my concern about such business practises. Seems it's all about individual business practises/policies and not government. My argument is that Government allows these practises/policies possible. We need legislation so that these multi nationals practises/policies are NOT possible.
I can only comment on how I find Insurance companies. I have had 2 claims over the years and they have been excellent. One car claim with AMMI, when someone backed into me. The car was still derivable. I was going overseas the next day. They took my car, got quotes and had it repaired and waiting for me when I returned from holiday. Taxis were paid to and from the airport. I could not ask for better service than this. The other claim was for contents insurance with APIA. A thunderstorm took out many of my electrical items, including the dishwasher, TV, recorder, and some other things. The claim was accepted (no questions, only receipts required, but items were paid for at current values) and I had a cheque in 48 hours. Again great service. I would strongly suggest using only reputable company s, after all, one does not want to claim but it is good to know when a claim is made it will be accepted. Obviously, if you look for cheap premiums, they have to cut service (and payouts) somewhere.
Whilst I do not defend the actions of insurance companies ( for years I have taken the position that their sole reason for existing is to find ways to avoid paying claims) I do think that the insured also needs to take some responsibility. Everyone should read the PDS of every insurance policy BEFORE they accept and pay for the product. It's no good saying later you didn't understand it. Yes some points can be obscure, yes they are not always written in plain English, yes the print is tiny, yes there may be many pages of it, but if you can't, won't or just don't read and understand it, then don't sign it and don't pay the premium.
However, I think that people who choose to live in obviously high risk areas e.g. on the edge of the bush, in known flood plains, close to the edge of cliff tops or on the beach etc should have to assume that risk.
And I do agree with Ductape that the 'excess' payment should be scrapped. The premiums paid are high enough and this is just another ploy to 'exclude' benefits from insurance.
The comments made me think about the rorts of home insurance. If your house is insured for, say, $300,000 and it burns down, the insurer can claim that the house was worth $400,000 and as it was under insured by $100,000, that amount is deducted from the amount insured. Interestingly, the amount that an insurance company values the property at includes the land value. If the dwelling burns down, the land remains.
If a house burned down in 1950's, the owner could ask for a cheque for the amount of the insurance but today, the insurer offers to rebuild the house to the same specifications as what was originally there. As we know, the cost to build a house is far less than the market value so, again, the insurer is able to dud the insured.
That is total utter rubbish Old Man - who are you insured with - Fly By Night Pty Ltd??
I pay an additional premium due to a pre existing illness. To me it is peace mind as I had a brain bleed whilst overseas resulting in 2 weeks in hospital, $15000 retrieval from the mountains by helicopter, accommodation costs for my husband and then medical evacuation back to Australia. Insurance paid everything, even a daily allowance for my husband even though he didn't obtain all receipts. Provide all medical info to the insurer, so they can't say they weren't advised.


A spot for chilling out and cultural events in Friedrichshain : the Coffehouse Les Enfants Terribles. On the menu: freshly prepared food, a great selection of hot and cold drinks, all topped off with tasty desserts. A neighbourhood friendly place where you can grab you coffee in the morning, find some fast but healthy meal at midday or take place to write, read or work, in a cosy atmosphere, and feel like home.
The baroque chic meets the bistro style, all modernized, to result a practical and comfortable room. You are first welcomed by the counter, a massive slate grey classic inspired with its moulding, made to measure to fit perfectly the needs of the team. Behind it, the wooden boards and dark steel pipe wall mounted and floor standing industrial shelf shows the brick wall at his best. The vibrating dark red wooden floor is slaked by the clear Perl white walls. A dark grey blue come between the windows to highlighting the architecture.
Request Interior Design Concept. Detailed Planning. Sanitation Layout. Tailored Counter, Storage and Stage. Furnishing research. Lighting.


text:
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Bishop Luciano Capelli sdb
"Lift up your hearts and all will be fine"
Luciano Don Capelli was born in Tirano (So) Italy on October 19th, !947. He attended primary school at Cologna di Tirano– Sondrio and went to high school at instituto Salesiano Montodine, in 1961.
He did his pre– aspirantate year in 1960-1961 and he went to instituto Salesiano San Bernardo for his aspiratate year. He did his novitiate at Missiagila Como from 1964– 1965 and made his first profession on August 16th, 1965.
From 1965– 1971 he was in the Philippines. He obtained his Bachelor Degree in Education– Philosophy studies in 1968, work as Biology instructor for Don Bosco Technical College of Engineering in 1969– 1970. Then in early 1971 he obtained Perpetual Profession and was a Classical Latin teacher in Don Bosco Seminary college.
In 1972 he returned to Italy to study theological studies at Instituto teologico Sam Tommaso. He was ordained a Deacon on December 10, 1974 at Sondrio. He completed his theological studies at 1975 in which he obtained his Bachelor Degree in theology. He was ordained a Priest in June 28, 1975 at Cologna di Tirano Sodrio (Italy).
In 1975 he went back to the Philippines and worked there until 1999. During those times, In 1976 to 1977 he was a Youth Center director for Don Bosco Technical College of Engineering. From 1977—1982 he become a Spiritual Director for Don Bosco Technical College of Engineering. In 1982 he was Rector for Don Bosco Technical institute at Tarlac, Philippians.
From !985 to 1991, he went for further studies and obtained his masters Degree in Education at Saint Joseph college of Graduate School, Manila. He was also Rector of Don Bosco Technical College of Engineering.
In 1991 to 1992 Bishop Luciano Capelli was Rector of Don Bosco Hall, for the boarding house for university Students in the Philippines. IFrom1992 to 1993 Bishop Capelli become a provincial council member and from 1993 to 1999 he was the Provincial for Manila and Papua New Guinea.
He came to the Solomons in 1999 as Rector for Don Technical Institute at Henderson in Honiara and this continued until 2007.
He was ordained Bishop of Gizo on October 21st , 2007 at Gizo by His Eminence Cardinal Joseph Zen– Cardinal of China.
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redpajama_set_name: RedPajamaCommonCrawl


text:
To put the "kibosh" on something means put an end to; dispose of decisively; finish something off; reject. Several theories exist as to the origin of the word in the early 1800s. Stephen Goranson of the American Dialect Society has suggested that it may be from the Arabic qurbāsh, Turkish qirbāch, or French courbache, which is spelled as "kurbash" in…
Hand phrases #2
Dab hand — expert at a particular activity (1600s) Underhanded — done in a secret or dishonest way; sneaky Upper hand — power, control, dominance In hand — under control; in reserve At hand — nearby; imminent On hand — immediately available; close by Take in hand — to take control of or to lead Get out of hand — to become chaotic and…
The word "hand" is used in many different ways in the language, just as we use our hands, those useful body tools, in many different ways. Here are some phrases and proverbs: All hands on deck — traditional nautical command for every sailor to report for duty; require everyone to work hard in order to achieve a particular aim (1700s)…
"Shenanigans" means trickery, underhand action, intrigue, skulduggery, high-spirited behavior, or mischief. The earliest record of it is in San Francisco (April 25 issue of Town Talk) in 1855. As to the source, word looks Irish, and there was no shortage of Irishmen working the California gold rush, so it's reasonable to suggest the Irish word sionnachuighm as the source, meaning…
fuddy-duddy
"Fuddy-duddy" is a slang term for a stuffy, fussy, or foolishly old-fashioned person. It is mildly derogatory but sometimes affectionate too. The word has been used throughout the 1900s. Synonyms are "frump," "school marm," and "old fart." The origin is uncertain, but "fuddy-duddy"may be American, possibly via Scotland. The first record appears to be from the Texas newspaper The Galveston…
"Hullabaloo" means a loud uproar, mixture of noises, din, commotion. Bartlett's Dictionary of Americanisms (1848) has it as "hellabaloo," meaning riotous noise and confusion, and says it is provincial in England. The word originated in the 1700s, though no one knows exactly where it came from. The word has been spelled in so many ways that "hullabaloo" has to be…
kerfuffle
A "kerfuffle" is a commotion, a fuss, a ruckus, a disruption, a brouhaha, a bother, a hoopla, or a flurry. It may generate a lot of sound and fury, but rarely represents anything serious. The word is informal; it doesn't appear in my Random House Unabridged Dictionary. Up until the 1960s, it was spelled in various ways — curfuffle, carfuffle,…
"Kibitz" is a Yiddish verb, meaning to be a spectator who offers often unwanted advice or commentary. A kibitzer, of course, is a person who likes to kibitz. The term can be applied to any activity, but is most commonly used to describe spectators in games such as contract bridge and chess. In bridge, a kibitzer simply refers to a…


Visual Description : New Hall punch bowl with window pattern. Central medallion inside punch bowl depicts three figures in a fenced area beside a building. There is a smaller house int eh background and plants and a butterfly in the foreground. On the outside is a repeated scene of three figures outside a building, with a fourth figure looking out the building window at the three others. Decorative motifs include flowers, patterned borders, butterflies, birds, and trees.


text:
Rena response update
Attached is the latest information available:
Salvage:
The salvage team has made good progress on getting oil off the vessel.
Pumping from the Rena to the bunker barge Awanuia began around 8.30pm last night. About 10 tonnes of oil was successfully transferred to tanks on board the Awanuia.
However, due to changing weather conditions and the need to make sure the crew from the salvage team stay safe, a decision was made to stop pumping.
The Awanuia is coming alongside and pumping is expected to resume shortly.
The salvage team also successfully transferred oil from the forward port tanks to the rear of the vessel where it can be pumped off. Work is continuing to pump fuel from the other forward tanks to the rear of the vessel, where it is easier and safer to take off the vessel.
A team of 25 salvage experts are on board the vessel.
A Boeing 747 has arrived with heavy equipment, including a Bell helicopter which has been flown to the site of the spill.
More heavy equipment has arrived by road.
This is an incredibly quick response for a salvage operation. It is estimated to take about two days to transfer all the fuel, but this is weather dependant.
The safety of the salvage team and crew remains paramount. If conditions worsen we will temporarily stop the operation until it�s safe to resume. Until then they will continue to pump fuel off the vessel for as long as it�s safe to work.
All vents on the ship are now sealed to prevent oil escaping.
There are 1700 tonnes of oil and another 200 tonnes of diesel which we hope to get off. We think there is about 100 tonnes of oil leaked into the duct keel.
As a precautionary measure, containers are being lashed more tightly to ensure the safety of the ship.
The weather is expected to deteriorate in the coming days, so we are working around the clock to remove the oil. The weather will impact on both the salvage and oil recovery effort. The forecast is for north-easterly winds increasing and this will have an effect on our response and salvage operations.
Salvage experts and naval architects on board are very closely monitoring the ship and have got sensors in place that will provide advance warning if the vessel�s structure is coming under too much stress.
Environmental team:
Areas that could be affected by a potential oil spill have been digitally mapped and we are working on response options in partnership with the public health service and local councils.
Fluorometers, to measure the effectiveness of the dispersant, have arrived from Singapore but there is not enough oil to test. Weathered oil is unlikely to disperse but fresh oil will be tested.
Teams are on M?t?t? and are setting up points for recovery. Trained people are on their way.
A survey has been done of Matakana and a plan approved for recovery.
The J Sweep operation has been successfully tested and has recovered 3500 tonnes of oily water which has been offloaded at the Port of Tauranga.
The naval vessel Manawanui is available and ready to assist to act as a floating platform for launching operations. More offshore recovery resources are arriving on Tuesday.
Operational teams are assessing both the Maketu Peninsula and Little Waihi estuaries for boom deployment if possible. Booms would be used to protect sensitive wetland areas from oil.
The Maketu and Little Waihi areas are a priority for the response team, which is getting expert advice from local environmental specialists, and local community.
We have the appropriate boom on standby and we also have plans in place for different deployment options, depending on weather conditions and the oil trajectory.
Wildlife:
Nine birds have been recovered, seven little blue penguins and two shags.
The wildlife centre is capable of managing 500 birds, with a team of 20 people working. We have more people on standby to assist.
Three shifts of people are working on the beaches with seven teams working on beaches from Mount Maunganui to Maketu spit and there are four teams on M?t?t?. They have compiled information on species and numbers to be expected.
A fur seal plan has been developed in the event that seals become affected by oil. This plan covers people, equipment and facilities as well as the possible capture of seals.
Defence Force:
A number of people and vessels have been turned away from the exclusion zone. These were vessels that did not need to be in the exclusion zone.
The HMNZS Endeavour arrived last night. It will be the command and control centre for the operation.
Should you wish to contact the Maritime New Zealand response team to ask questions or offer to help, please email them at [email protected]� If you see oil on the shoreline, please report it by calling 0800 OIL SPILL (that is 0800 645 774) and to report oiled wildlife, please call 0800 333 771.
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