text:
\section{Introduction}

Information security is a core of cybersecurity in the digital era. Cryptography provides a vital tool to achieve information security in cyber environment, particularly when untrusted channels are used. Unfortunately, the current widely-used public-key cryptographic infrastructure is threaten by a quantum computer~\cite{shor1997}. To defeat the threat from the quantum world, quantum key distribution (QKD)~\cite{bennett1984} based on the laws of quantum mechanics provides a long-term solution, which has been proved its information-theoretical security. The key generated via QKD can be applied to one-time-pad algorithm, guaranteeing information-theoretically secure communication~\cite{nudt1, nudt2}. Due to plenty of efforts, QKD has developed with a fast pace even to be globalized and commercialized, becoming one of the most mature applications in the field of quantum information~\cite{takesue2007, scheidl2009, sibson17, ding2017, eriksson2019}. Owing to such fast development, standardization of QKD is being considered in the European Telecommunications Standards Institute~(ETSI)~\cite{ISGofETSI}, the International Standard Orgnization~(ISO)~\cite{StandardsNews}, and the International Telecommunication Union~(ITU).

However, a practical QKD system may behave differently from its theoretical model which discloses security loopholes that can be exploited by an eavesdropper, Eve, to learn the secret key, compromising the practical security of QKD systems~{\color{black}\cite{brassard2000,lydersen2010a,xu2010,gerhardt2011,bugge2014,huang2016,sajeed2016,huang2018,huang2019,chistiakov2019,gras2019,huang2018a,xu2020}}. To defeat quantum hacking, an effective countermeasure is to employ an innovative protocol, like measurement-device-independent QKD (MDI QKD)~\cite{lo2012} and twin-field QKD (TF QKD)~\cite{lucamarini2018, curty2019}, to remove the threat from loopholes. However, the high demand of technique and relative low key rate of the innovative protocols limit their application and commercialization. Therefore, to relieve the security threat on the QKD systems in use, it is essential to patch the loopholes in the existing QKD systems~\cite{Koehler2018, Koehler2018a}, most of which employ prepare-and-measure QKD protocol.

As countermeasures, patches, instead of ending the hacking story, lead to a new era of quantum hacking -- inspire quantum attackers to conduct a new round of hacking investigation on the patched system. Patches motivate Eve to discover the {\color{black} imperfection of the patches themselves and the remaining loopholes that the patches fail to close.} Our work {\color{black}proposes a more general blinding attack to bypass the photocurrent monitor}. We discover that{\color{black}, for the detector under test,} bright \emph{pulses} can blind APD intermittently and meanwhile bypass the alarm of photocurrent monitor, although reasonable qubit error rate (QBER) is introduced. We call this method as \emph{pulse illumination attack}.

The pulse illumination attack is a more general type of detector blinding attack than the original one that uses continuous wave~(c.w.) light. In this attack, Eve does not only exploit the mode switch between the linear mode and Geiger mode via light shining, but also makes refined use of the hysteresis current after pulse shining to create a period of full blinding and detection control. The deep investigation on the loopholes strengthens Eve's hacking capability, and thus passes the challenge of protecting the QKD system to countermeasure proposers again. This study emphasizes the significance of further investigating the imperfections of single-photon detector, in order to improve the security property of the standard prepare-and-measure QKD systems that are deployed the most in field~\cite{peev2009, sasaki2011, liao2017}. Moreover, this study contributes a general testing item to the security certification list of QKD standard, which is being drafted in several international organizations, e.g.\ ETSI, ISO, and ITU \cite{ISGofETSI, ETSIwhitepaper,StandardsNews}.

\section{From c.w.\ illumination attack to pulse illumination attack}
\label{sec:theory}

In this section, we briefly review the origin blinding attack, i.e., c.w.\ illumination attack, and then introduce the countermeasure of the photocurrent monitor that is believed to be effective to blinding attacks. Finally, we propose pulse illumination attack as a new form of blinding attack that can bypass the photocurrent monitor.

For a BB84 QKD system, Eve can apply the c.w.\ blinding attack on APDs to eavesdrop the information. In the original c.w.\ blinding attack, Eve injects continuous light to generate a huge photocurrent through APD, which lowers the bias voltage and pulls the APD back to the linear mode that is insensitive to a single photon. Then, she conducts a fake-state attack as follows. She first intercepts and measures each state sent by Alice, and resends a trigger pulse encoded by her measurement result to control Bob's clicks as the same as hers. For more details about the original c.w.\ blinding attack, see \cref{sec:c.w.}.

To patch the loophole exploited by the blinding attack, some QKD systems including our testing object in this work adopt a photocurrent monitor as a countermeasure against the blinding attack~\cite{lydersen2010a, yuan2010, huang2016}. This countermeasure bases on an intuitive assumption that a blinding attack will certainly generate a distinguishable low-frequency photocurrent in the circuit of the detector. The monitor extracts the low-frequency photocurrent as an alarm of the blinding attack. Once the extracted photocurrent reaches an alarming threshold, the blinding attack is considered to be launched. Please note that the extracted photocurrent is named as reported photocurrent in the following text.

However, we find that this countermeasure can not completely hinder the pulse illumination attack. This is because the aforementioned assumption about the photocurrent under a blinding attack does not stand when bright optical pulses are sent to blind an APD. In this attack, a group of blinding pulses accumulatively introduces a high photocurrent. This photocurrent is also able to lower the bias voltage across the APD. As a result, the detector is blinded at that time. After the blinding pulses are gone, the detector is still blinded for a certain period, because the photocurrent gradually reduces due to capacitors in the detector. Thus the detector keeps being blinded until the photocurrent becomes fairly weak. Eve can exploit the	 blinded period to launch the fake-state attack to eavesdrop the information. Theoretically, the length of the blinded period is positively correlated with the energy of the blinding-pulse group.

Unlike the constant high photocurrent introduced by the c.w.\ illumination attack, here the photocurrent varies over time. The photocurrent monitor takes this current as high-frequency noise and ignores most of it. Therefore, Eve can apply the pulse illumination attack to eavesdrop the information without being noticed by the photocurrent monitor.

\section{Experimental demonstration}
\label{sec:experiment}
As a third-party evaluator, we conducted tests about the pulse illumination attack on a APD-based single-photon detector module, provided by an independent party. In the tests, we assume that Eve only knows the public information of the detector as prior knowledge to show a real-life hacking scenario. For the single-photon detector module we tested, the frequency of gate signal is \SI{40}{\mega \hertz}, and the photocurrent monitor inside the module first filters the photocurrent in the circuit of the detector via a lowpass filter to avoid high-frequency noise. The alarming threshold is set as \SI{10}{\micro \ampere} {\color{black}by the independent detector provider}, which is an {\color{black} optimum-performance} value to safely detect c.w.\ illumination blinding attack {\color{black} in practice}. The threshold is far lower than the illegitimate value (\SI{31}{\micro \ampere}) when c.w.\ illumination blinding attack works, as well as leaves a margin to the value of normal working state (\SI{1.4}{\micro \ampere}) to avoid false alarms {\color{black}due to occasionally in-field fluctuation}. The tested detector works at \SI{-50} {\celsius} with dark count rate of $5 \times 10^{-6}$ per gate and 3\% after-pulse probability.

\begin{figure}\centering
	\begin{tikzpicture}[controlpanels/.style={yellow!30!brown!20!,rounded corners,draw=black,thick},
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  \draw (bsignal) to  (blind);
  \draw  (tsignal) to  (trigger);
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  \draw  (sg_c2) to  [out=0,in=180]  (tsignal);
  \draw  (dsg) to  [out=0,in=175]  (tmp_relay);
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  \draw  (blind) to  (sa);
  \draw (trigger) to  (voa);
	  \draw (sa) to  [out=0,in=180] (bs_west);
	  \draw (voa) to  [out=0,in=180] (bs_west);
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	  \begin{scope}
	  \end{scope}
	  \end{tikzpicture}
	\caption{Experimental setup for the pulse illumination attack. The double-channel arbitrary waveform generator excites \SI{1550}{\nano \meter} lasers to generate the blinding pulses and the trigger pulses. The trigger pulses do not contribute to blind the APD and they are just used for calibrating the blinded period and controlling Bob's click. The manual variable attenuator and the digital variable attenuator modulate the energy of the blinding pulses and trigger pulses precisely. The 50:50 beam splitter merges the blinding pulses and the trigger pulses. We use a digital signal generator to synchronize our blinding pulses and the trigger pulses with the single-photon detector's clock. The power meter monitors the total energy of pulses going to the single-photon detector.}
	\label{fig:bldsetup}
\end{figure}

\begin{figure*}
	\centering
	\includegraphics[scale=0.6]{attack2.pdf}
	\caption{Oscillograms where a) the detector is blinded by a group of 500-cycle blinding pulses and b) a trigger pulse with energy $E_\text{never}$ / $E_\text{always}$ is sent during the blinded period to get no click/click.}
	\label{fig:attack}
\end{figure*}

Our experiment setup is shown in \cref{fig:bldsetup}. A digital signal generator synchronize the whole system. The channel 1 of the waveform generator excites a \SI{1550}{\nano \meter} laser diode to launch a group of blinding pulses with the frequency as the same as that of the SPAD gate, \SI{40}{\mega \hertz}. In our experiments, the width of each blinding pulse was set as \SI{4}{\nano \second}, and we kept the energy of each blinding pulse being \SI{13.32}{\pico \joule}. The blinding pulses were applied outside the gate signals to avoid unwanted clicks caused by the blinding pulses. A group of blinding pulses only triggers a click at the beginning of the group, which is followed by \SI{5}{\micro \second} dead time. After that, the detector is blinded due to the accumulated photocurrent and Eve can launch the fake-state attack in this blinded period during which no dark count exists. Long intervals between groups are necessary for reducing the low-frequency photocurrent and avoiding being noticed by the photocurrent monitor. \SI{2}{\milli \second} interval can satisfy such requirement in our testing. This experimental result is shown in \cref{fig:attack}a. The detailed analysis about the parameters of blinding pulses are given in \cref{sec:detail}.

\begin{figure}
	\centering
	  \begin{tikzpicture}
	\begin{groupplot}[
	group style={
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	(125,0) (150,0) (151.5,1.5) (153,0) (175,0) (176.5,1.5) (178,0) (185,0)

	 (214,0) (225,0) (226.5,1.5) (228,0) (250,0) (251.5,1.5) (253,0) (275,0) (276.5,1.5) (278,0) (300,0) (301.5,1.5) (303,0)};

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	 \node [] at (axis cs:112,1.3) {Blinding pulses};
	 \node [align=center] at (axis cs:250,0.8) {Trigger \\ pulse};
	 \draw [->,>=stealth] (axis cs:255,0.2) -- (axis cs:273,0.2);
	 \addplot[red, densely dotted] coordinates{(273.5,0) (275.5,0.3) (277.5,0)};
	 \coordinate (bld illm) at (axis cs:137, 1.1);
	 \coordinate (mid bld) at (axis cs:137, 1.5);
	 \coordinate (trg pls) at (axis cs:275.5,0.4);
	 \coordinate (mid trg) at (axis cs:275.5, 1.5);

	 \draw [black!70, densely dotted, ->] (trg pls) to (mid trg) to node [auto,below,font=\tiny,sloped,align=center,xshift=6mm] {inside} +(0, 0.47cm);
	 \draw [decorate, decoration={brace}, yshift=1.8cm] (axis cs: 65, -0.1) -- node [above, align=center] {Dead time \\ (\SI{5}{\micro \second})}(axis cs: 112, -0.1);
	\end{groupplot}
	\end{tikzpicture}

	  \caption{The methodology of calibrating the blinded period after a group of blinding pulses. We apply a weak trigger pulse that contains 67 photons as a discriminator of blinding inside the gate after the blinding pulses. We move the trigger pulse to right gate-by-gate and repeat the calibration to probe the boundary of the blinded period.}
	  \label{fig:calibration}
\end{figure}

\begin{table}[htbp]
	\centering
	\caption{The blinded period, the number of fully controllable gates, and the reported photocurrent under pulse illumination with different cycle numbers. The dead time caused by the initial blinding pulse is not included in the blinded period. The interval length between two groups of blinding pulses is set as \SI{2}{\milli \second}. In all these cases, the reported photocurrent is close to that in normal working state, \SI{1.4}{\micro \ampere}. The built-in alarming threshold of the photocurrent monitor is \SI{10}{\micro \ampere}.}
	\label{tab:blinded range}
	\begin{tabular}{p{1.5cm}<{\centering}p{1.5cm}<{\centering}p{1.7cm}<{\centering}p{1.9cm}<{\centering}}
	\toprule
	\makecell[c]{Cycle \\ number} & \makecell[c]{Blinded \\ period \\ (\si{\micro \second})} & \makecell[c]{Fully \\ controllable \\ gates} & \makecell[c]{Reported \\ photocurrent \\ (\si{\micro \ampere})} \\
	\midrule
	250& 2.025& No data& 1.8\\
	300& 20.025& No data& 1.8\\
	350& 45.025& 72& 1.9\\
	400& 100.05& 150& 1.9\\
	450& 135.05& 330& 2\\
	500& 195.05& 690& 2.1\\
	\bottomrule
	\end{tabular}
\end{table}

The channel 2 of the waveform generator excites another \SI{1550}{\nano \meter} laser diode to launch a trigger pulse to calibrate the length of the blinded period and the fully controllable range inside. The methodology of calibrating a blinded period is shown in \cref{fig:calibration}. A trigger pulse contains 67 photons, which can trigger a click in Geiger mode but is not strong enough to trigger a click in the linear mode. We first apply the trigger pulse at the gate just after the group of blinding pulses. If the trigger pulse causes no click, the detector is blinded during this gate. The trigger pulse is then moved away from the group of blinding pulses gate-by-gate to repeat the calibration process until the trigger pulse causes a click. The period of no click is the blinded period. The length of the blinded period generated by a group of 250-/300-/350-/400-/450-/500-cycle blinding pulses is shown in \cref{tab:blinded range}. As the trigger pulse contains multiple photons, the length of the blinded period here is just conservative estimations.

\begin{figure}
	\begin{center}
	\begin{tikzpicture}[trim left=-0.5cm]
	\begin{groupplot}[
	group style={
	group size=2 by 2,
	xlabels at=edge bottom,
	ylabels at=edge left,
	},
	height=4cm,
	width=5cm,
	xlabel=Time,
	ylabel=Energy,
	x unit=\si{\micro \second},
	y SI prefix=femto, y unit=\si{\joule}
	]

	\nextgroupplot[title=350-cycle, xmin=7.25, xmax=8.75, xtick={7.25, 8.75}]

	\addplot+ [smooth,tension=0.2] table[col sep=comma, x=t, y=Ea] {data/350cycle-ahn-zoomin.csv};
	\addplot+ [smooth,tension=0.2] table[col sep=comma, x=t, y=Eh] {data/350cycle-ahn-zoomin.csv};
	\addplot+ [smooth,tension=0.2, mark=triangle*] table[col sep=comma, x=t, y=En] {data/350cycle-ahn-zoomin.csv};

	\nextgroupplot[title=400-cycle, xmin=7.25, xmax=11, xtick={7.25,10, 11}]
	\addplot+ [smooth,tension=0.2] table[col sep=comma, x=t, y=Ea] {data/400cycle-ahn-zoomin.csv};
	\addplot+ [smooth,tension=0.2] table[col sep=comma, x=t, y=Eh] {data/400cycle-ahn-zoomin.csv};
	\addplot+ [smooth,tension=0.2, mark=triangle*] table[col sep=comma, x=t, y=En] {data/400cycle-ahn-zoomin.csv};

	\nextgroupplot[title=450-cycle, xmin=7.25, xmax=15.5, xtick={7.25,11.25, 15.5}]
	\addplot+ [smooth,tension=0.2] table[col sep=comma, x=t, y=Ea] {data/450cycle-ahn-zoomin.csv};
	\addplot+ [smooth,tension=0.2] table[col sep=comma, x=t, y=Eh] {data/450cycle-ahn-zoomin.csv};
	\addplot+ [smooth,tension=0.2, mark=triangle*] table[col sep=comma, x=t, y=En] {data/450cycle-ahn-zoomin.csv};

	\nextgroupplot[title=500-cycle, xmin=7.25, xmax=24.5, xtick={7.25,12.5, 24.5}, legend columns=3, legend entries={$E_{\text{always}}$,$E_{\frac{1}{2}}$,$E_{\text{never}}$}, legend style={at={(-0.1, -0.6)}, anchor={south}}]
	\addplot+ [smooth,tension=0.2] table[col sep=comma, x=t, y=Ea] {data/500cycle-ahn-zoomin.csv};
	\addplot+ [smooth,tension=0.2] table[col sep=comma, x=t, y=Eh] {data/500cycle-ahn-zoomin.csv};
	\addplot+ [smooth,tension=0.2, mark=triangle*] table[col sep=comma, x=t, y=En] {data/500cycle-ahn-zoomin.csv};

	\end{groupplot}
	\end{tikzpicture}

	\end{center}

	  \caption{$E_{\text{always}}$, $E_{\frac{1}{2}}$ and $E_{\text{never}}$ inside the fully controllable range of a blinded period generated by a group of 350/400/450/500-cycle blinding pulses. {\color{black} The data not satisfying the fully controllable condition ($E_{\text{always}} < 2 E_{\text{never}}$) are not included in this figure. }The time origin is the arriving of the first blinding pulse in the group. The inflection points are the moments that the blinding pulses end, where the accumulated photocurrent reaches to the maximum.}
	  \label{fig:controllablearea}
\end{figure}

By a similar methodology but varying the energy of the trigger pulse, we can further calibrate a fully controllable range. As shown in \cref{fig:attack}b, at each gate inside the blinded period, we vary the energy of a trigger pulse to observe the click probability and record the energy that can trigger a click with the probability of 100\%/50\%/0\% as $E_{\text{always}}$/$E_{\frac{1}{2}}$/$E_{\text{never}}$. If $E_{\text{always}} < 2 E_{\text{never}}$, the detector at this gate in the blinded period is fully controllable by Eve for a BB84 QKD system (while the rest gates of the blinded period also do not have dark counts and are partly controllable). The experimental data of the fully controllable range in the blinded period generated by a group of 350-/400-/450-/500-cycle blinding pulses are shown in \cref{fig:controllablearea}. Note that in all the testing above, the reported photocurrent keeps being far lower than the built-in alarming threshold of the photocurrent monitor (\SI{10}{\micro \ampere}), as shown in \cref{tab:blinded range}.

\section{Security analysis for a decoy-state BB84 QKD system}
\label{sec:simulation}
In this section, we analyse Eve's maximum-profit strategy of attacking a real-life decoy-state BB84 QKD system via pulse illumination, and we further study the threat of this attack to the system. Here the detection parameters are from the Gobby-Yuan-Shields (GYS) experiment~\cite{gobby2004}. The interval length, the blinded period, and the fully controllable range are from our experimental results as shown in \cref{tab:blinded range}.

\subsection{Eve's maximum-profit strategy}
The strategy of Eve's attack is as follows. We assume Eve uses lossless channels to connect Alice and Bob. Without introducing deviation to the normal value of total gain, she launches fake-state attack during the fully controllable range, while blocks or passes the state from Alice during the unblinded time. Therefore, to eavesdrop the maximum information, she needs to optimize the parameters of her attack.

Specifically, three parts constitute the total gain under Eve's attack -- the click trigger by each group's first blinding pulse, the gain under fake-state attack ($Q_\omega^\text{Eve}$) during the fully controllable range, and the gain that Eve blocks or passes the state from Alice during the unblinded period. Regarding the fake-state attack, Eve first measures Alice's state with a perfect detector and resends to Bob by a trigger pulse with energy $E_\text{always}$. Bob's basis choice matches to Eve's half of the time, which triggers a click at Bob's detector with 100\% probability. Thus, $Q_{\omega}^\text{Eve} = \frac{1}{2} (1-e^{-\omega})$, where $\omega \in \{\mu = 0.6, \nu = 0.2, 0\}$ is the mean photon number of the signal state, the decoy state, and the vacuum state. When Eve blocks Alice's states, only dark counts, $Y_0 = 1.7 \times 10^{-6}$, happen at Bob's detector; {\color{black} when Eve passes Alice states via the lossless channel, the corresponding gain is $Q_\omega^\text{pass} = Y_0+1-e^{- \eta_\text{ch} \eta_\text{Bob} \omega} = Y_0+1-e^{- \eta_\text{Bob} \omega}$ (where $\eta_\text{ch} = 1$ is the transmittance efficiency of Eve's lossless channel and $\eta_\text{Bob}$ is the transmittance of Bob's optical device).} Therefore, the total gain under the pulse illumination attack is
{\color{black}
\begin{equation} \label{Q}
\begin{aligned}
Q_\omega &= \frac{1 + p Q_\omega^\text{Eve} N_{\text{control}}}{N_{\text{interval}}} \\
    &+ \frac{(N_{\text{interval}} - N_{\text{blind}} - N_{\text{dead}}) [\gamma Q_{\omega}^{\text{pass}} + (1 - \gamma) Y_0]}{N_{\text{interval}}} \\
    &= \frac{1}{ N_{\text{interval}}}+ p Q_\omega^\text{Eve} \alpha + (1 - \beta) [\gamma Q_{\omega}^{\text{pass}} + (1 - \gamma) Y_0],\\
\end{aligned}
\end{equation}
}
where $N_\text{control}/N_\text{blind}/N_\text{dead}/N_\text{interval}$ is the gate number of the fully controllable range/the blinded period/the dead time/the interval length for a group of blinding pulses. $\alpha = N_{\text{control}}/N_{\text{interval}}$, representing the controllable proportion of gates under the attack. $1 - \beta = (N_{\text{interval}} - N_{\text{blind}} - N_{\text{dead}})/N_{\text{interval}}$, representing the proportion of gates that are not affected by the blinding. $p \in [0, 1]$ is the proportion of $N_\text{control}$ that Eve launches the fake-state attack. $\gamma \in [0, 1]$ is the ratio that Eve {\color{black} passes} the photons from Alice during the unblinded time in each interval. Accordingly, the total QBER is
{\color{black}
\begin{equation} \label{E}
\begin{aligned}
E_\omega &= \frac{1}{Q_\omega} \{\frac{e_0}{N_{\text{interval}}} + p Q_\omega^\text{Eve} \alpha e_\text{det} \\
    &+ (1-\beta)[\gamma E_{\omega}^{\text{pass}} Q_{\omega}^{\text{pass}} + (1 - \gamma) Y_0 e_0]\},
\end{aligned}
\end{equation}
}
where $E_\omega^{\text{pass}} Q_\omega^{\text{pass}} = e_0 Y_0 + e_\text{det}(1 - e^{- \eta_\text{Bob} \omega}).$ $e_0 = 0.5$ is the error rate of the background noise. $e_{\text{det}} = 3.3\%$ is the misalignment error rate of the QKD optical system.

According to the principle of the attack, Eve has to keep the total gain being indistinguishable with that in the normal working state~({\color{black}$Q_{\omega}^{\text{normal}} = Y_0 + 1 - e^{-\eta_\text{Bob} \eta_\text{ch} \omega}$, where $\eta_\text{ch} = 10^{\frac{-0.21 L}{10}}$} is the transmittance of the quantum channel of the QKD system as a function of the channel length $L$) to hide her existence by modulating $p$ and $\gamma$. Moreover, she will make {\color{black} $p$ ($\gamma$) as high (low) as possible}. Consequently, when Eve tries to make $p = 1$ and {\color{black}$\gamma = 0$} initially, she may confront with two cases:
\begin{itemize}
	\item [\emph{I:}] $Q_\mu > Q_\mu^{\text{normal}}$.
		In this case, Eve only needs to decrease $p$ to apply less fake-state attack during the fully controllable range to ensure $Q_\mu = Q_\mu^{\text{normal}}$. Thus, she can obtain almost all the information as all rounds of communication are either controlled or blocked.
	\item [\emph{II:}] $Q_\mu < Q_\mu^{\text{normal}}$.
		In this case, Eve has to {\color{black} increase} $\gamma$ to allow some photons pass from Alice to Bob without any intervention during the unblinded time, while keeps $p=1$, and then increase $Q_\mu$ to hide herself. Therefore, she can just obtain part of the total information in the communication.
\end{itemize}
Under this strategy, the QKD system cannot be aware of Eve's attack by checking the total gain. The QBER during the attack is shown in~\cref{fig:simulation}a.

\subsection{The key rate estimated by Alice and Bob under pulse illumination attack}
According to the decoy-state protocol~\cite{ma2005, wang2005a}, Alice and Bob can estimate the yield and the error rate of a single photon, which are given by
\begin{equation}\label{YE_1}
\begin{aligned}
Y_1^L& =\frac{\mu}{\mu \nu-\nu^{2}}\left(Q_{\nu} e^{\nu}-Q_{\mu} e^{\mu} \frac{\nu^{2}}{\mu^{2}}-\frac{\mu^{2}-\nu^{2}}{\mu^{2}} Y_{0}\right)\\
e_1^U& =\frac{E_{\nu} Q_{\nu} e^{\nu}-e_{0} Y_{0}}{Y_{1}^{L} \nu}.
\end{aligned}
\end{equation}
Submitting \cref{Q}, \cref{E}, and \cref{YE_1} into the GLLP~\cite{gottesman2004}, Alice and Bob can estimate the lower bound of the key rate as
\begin{equation}\label{GLLP}
	R^L_{\text{est}} = q\left\{-Q_{\mu} f\left(E_{\mu}\right) H_{2}\left(E_{\mu}\right)+ \mu e^{-\mu} Y_{1}^L\left[1-H_{2}\left(e_{1}^U\right)\right]\right\}.
\end{equation}
Here $q=1/2$ for the BB84 protocol, $f(E_\mu)=1.2$ for error correction, and $H_2(x)$ is Shannon entropy. The $R^L_{\text{est}}$ under no/350-/400-/450-/500-cycle pulse illumination attack with Eve's strategy is shown by the blue line in~\cref{fig:simulation}b/c/d/e/f.

\begin{figure}
	\centering
  \begin{tikzpicture}[trim left=-0.8cm]
\begin{groupplot}[
group style={
	group name=my plots,
	group size=2 by 3,
	vertical sep=2cm,
	horizontal sep=0cm
},
ymode=log,
xmax=170,
width=5.45cm,
height=4cm,
extra x tick style={grid={major},grid style={dashed}, ticklabel style={anchor=south}},
extra x tick labels=\empty,
xlabel=Channel length,
x unit=\si{\kilo \meter},
major tick length=2.5pt,
]
\nextgroupplot [title=QBER, no markers, ymode=normal, legend entries={$E_{\mu}^{\text{norm}}$, $E_{\mu}$}, legend style={at={(0.05,0.95)}, anchor={north west}, cells={anchor=west}}]
\addplot+[cyan, dotted] table[col sep=comma, x=L, y=E_normal]  {data/simulation-data/E_norm.csv};
\addplot+[magenta, dashdotdotted] table[col sep=comma, x=L, y=E_attack]  {data/simulation-data/E_norm.csv};

\nextgroupplot [title=$R^L_\text{est}$ (no attack), yticklabel pos=right,yticklabel style={anchor=east},no markers]
\addplot+[] table[col sep=comma]  {data/simulation-data/RL_noattack.csv};

\nextgroupplot [title=350-cycle, ymin=1e-7, ymax=1e-2, no markers, extra x ticks={96, 99.5}, xtick={0, 99.5, 150}, xmax=120]
\addplot+[] table[col sep=comma, x=L, y=RL_esti]  {data/simulation-data/R_350.csv};
\addplot+[dashed] table[col sep=comma, x=L, y=RL_real]  {data/simulation-data/R_350.csv};
\addplot+[dashdotted] table[col sep=comma, x=L, y=RU_real]  {data/simulation-data/R_350.csv};
\node [xshift=2.6cm, yshift=-3.2cm] {96};

\nextgroupplot [title=400-cycle, ymin=1e-7, ymax=1e-2,ytick=\empty, no markers, extra x ticks={62, 79}, xtick={0, 62, 79, 100, 150}, xmax=120]
\addplot+[] table[col sep=comma, x=L, y=RL_esti]  {data/simulation-data/R_400.csv};
\addplot+[dashed] table[col sep=comma, x=L, y=RL_real]  {data/simulation-data/R_400.csv};
\addplot+[dashdotted] table[col sep=comma, x=L, y=RU_real]  {data/simulation-data/R_400.csv};

\nextgroupplot [title=450-cycle, ymin=1e-7, ymax=1e-2,no markers, extra x ticks={37, 60}, xtick={0, 37, 60, 100, 150}, xmax=120]
\addplot+[] table[col sep=comma, x=L, y=RL_esti]  {data/simulation-data/R_450.csv};
\addplot+[dashed] table[col sep=comma, x=L, y=RL_real]  {data/simulation-data/R_450.csv};
\addplot+[dashdotted] table[col sep=comma, x=L, y=RU_real]  {data/simulation-data/R_450.csv};

\nextgroupplot [title=500-cycle, ymin=1e-7, ymax=1e-2,ytick=\empty, no markers, legend columns=3, legend entries={$R^L_{\text{est}}$,$R^L_{\text{real}}$,$R^U_{\text{real}}$}, legend style={at={(0, -0.7)}, anchor={south}}, extra x ticks={20, 43}, xtick={0, 20, 43, 100, 150}, xmax=120]
\addplot+[] table[col sep=comma, x=L, y=RL_esti]  {data/simulation-data/R_500.csv};
\addplot+[dashed] table[col sep=comma, x=L, y=RL_real]  {data/simulation-data/R_500.csv};
\addplot+[dashdotted] table[col sep=comma, x=L, y=RU_real]  {data/simulation-data/R_500.csv};

\end{groupplot}
\draw [font=\sf \scriptsize](my plots c1r1.north west) node [xshift=0.1cm, yshift=0.5cm] {a)};
\draw [font=\sf \scriptsize](my plots c2r1.north west) node [xshift=0.1cm, yshift=0.5cm] {b)};
\draw [font=\sf \scriptsize](my plots c1r2.north west) node [xshift=0.1cm, yshift=0.5cm] {c)};
\draw [font=\sf \scriptsize](my plots c2r2.north west) node [xshift=0.1cm, yshift=0.5cm] {d)};
\draw [font=\sf \scriptsize](my plots c1r3.north west) node [xshift=0.1cm, yshift=0.5cm] {e)};
\draw [font=\sf \scriptsize](my plots c2r3.north west) node [xshift=0.1cm, yshift=0.5cm] {f)};
\end{tikzpicture}

  \caption{The simulation results of the security analysis. a) The QBER with/without Eve's pulse illumination attack. Here 350-/400-/450-/500-cycle attack introduce the same QBER. b) The $R^L_{\text{est}}$ when the system works without pulse illumination attack. The key rate decreases dramatically to almost 0 when the length is longer than \SI{130}{\kilo \meter}. c)/d)/e)/f) The $R^L_{\text{est}}$, $R^L_{\text{real}}$ and $R^U_{\text{real}}$ under Eve's pulse illumination attack with 350-/400-/450-/500-cycle illumination pulses.}
  \label{fig:simulation}
\end{figure}

\subsection{The real key rate of the QKD system under pulse illumination attack}
To judge whether Alice and Bob overestimate the key rate and thus introduce insecurity, we give the \emph{real} upper bound and the lower bound of the key rate when the pulse illumination attack with Eve's strategy is applied.

The real yield of a single photon $Y_1^{\text{attack}}$ and its error rate $e_1^{\text{attack}}$ under Eve's attack strategy can be calculated as
\begin{equation}
\begin{aligned}
	Y_1^{\text{attack}} &= Y_0 +\eta_{\text{Bob}} -Y_0 \eta_{\text{Bob}},\\
	e_1^{\text{attack}} &=\frac{1}{Y_1^{\text{attack}}} (e_{\text{det}} \eta_{\text{Bob}} + e_0Y_0).
\end{aligned}
\end{equation}
Then, the real upper bound and the lower bound of the key rate can be written as
\begin{equation}\label{True_kr_upper}
	R^U_{\text{real}} = \frac{1}{2} (1-\beta)\gamma \mu e^{-\mu} Y_1^{\text{attack}}  [1-H_2(e_1^{\text{attack}})]
\end{equation}
and
\begin{equation}\label{True_kr_lower}
\begin{aligned}
	R^L_{\text{real}} &= \frac{1}{2} (1-\beta)\gamma \{\mu e^{-\mu} Y_1^{\text{attack}}  [1-H_2(e_1^{\text{attack}})] \\
	&- Q_\omega^{\text{pass}} f_{EC} H_2(E_\omega^{\text{pass}})\}.
\end{aligned}
\end{equation}
$R^L_{\text{real}}$ and $R^U_{\text{real}}$ under 350-/400-/450-/500-cycle pulse illumination attack with Eve's strategy are shown in~\cref{fig:simulation}c/d/e/f as the dashed and dash-dot lines.
The results show that Eve can successfully hack the QKD system and learn the secret key under certain communication distance between Alice and Bob for the cases considered here. Take the scenario of 500-cycle pulse illumination attack as an example, we can easily find that when the channel length is between 20 km and 43 km, the estimated key rate by Alice and Bob is higher than the real lower bound but lower than the real upper bound. Thus, Alice and Bob overestimates the key rate. When the length of the quantum channel is longer than \SI{43}{\kilo \meter}, we can ensure that the key rate estimated by Alice and Bob is insecure, because $R^L_{\text{est}}$ is higher than $R^U_{\text{real}}$.
{\color{black}
These results are reasonable.
When the channel length is short Eve has to pass a large portion of signals from Alice, and thus her threat to the QKD system is weak.
The GLLP equation still can estimate a secret key rate in the secure range.
However, as the channel length gets longer, Eve can block more signals during the unblinded time to enlarge the proportion of the eavesdropped keys, and thus threaten the security significantly.
The GLLP equation then cannot correctly estimate the secret key rate.
}
\section{Discussion}
\label{sec:disc}
As we described above, the pulse illumination attack can hack the passive quenching single photon detector to eavesdrop secret information while bypass its photocurrent monitor.
Here we extend the discussion to the effectiveness of the pulse illumination attack on detectors of other architectures or with other countermeasures.
The pulse illumination attack can blind high-speed self-differential detectors~\cite{dynes2016, yuan2018}, as this kind of detectors can be blinded by triggering a sequence of detection events~\cite{jiang2013}, which can be achieved by the pulse illumination attack with a low blinding pulse energy.
For active-quenching detectors without a bias resistor~\cite{zheng2018}, blinding by bright illumination seems difficult.
However, the work of thermal attack shows that this kind of detectors can also be blinded by the thermal effect of the injected bright light~\cite{lydersen2010b}, which implies that the pulse illumination attack with a higher blinding pulse intensity may hack such detectors.
{\color{black} In this case, the pulse illumination attack tends to introduce a relatively higher generated photocurrent which might reveal the existence of Eve.
However, Eve can further enlarge the inter-group interval to decrease the low-frequency components of the generated photocurrent and hide herself again.}
A sophisticated attack-monitoring method shown in Ref.~\cite{silva2012} exploits the accumulating statistics of times between consecutive detection events.
As the pulse illumination attack has various adjustable parameters, its fingerprint on the statistics might be attenuated.
Recently, a countermeasure against detector-control attacks using randomly switching variable attenuators (VA) is proposed~\cite{qian2019}, where the switching of a VA's attenuation value  under c.w.\ illumination will introduce random clicks and raise QBER to trigger the alarm.
However, the pulse illumination attack does not illuminate constantly, and thus the switching probably does not lead to any abrupt changes on injected light to cause random clicks.
The practical effectiveness of these countermeasures under the pulse illumination attack should be analysed in a future testing.

{\color{black}
Lowering the alarming threshold of the photocurrent monitor can not effectively detect the pulse illumination attack.
In addition to frequent false alarms introduced by this method, Eve can attenuate the reported photocurrent by enlarging the intervals to break this defense, as shown in \cref{sec:detail}.
Improving the stop band of the filter in the photocurrent monitor can reveal more evidences of the pulse illumination attack, depending on the value improved.
However, improving the stop band extremely will also make the monitor in trouble with abundant false alarms by noises and lose its functionality.
An extreme case is removing the filter to thoroughly expose the uprising caused by the blinding pulses.
In this case, the alarm will definitely be triggered with the pulse illumination attack, but frequent false alarms will also be trigger when the detector is working normally.
}
The feasibility of {\color{black}any change of parameters in the photocurent monitor} should be tested in a future experiment, and the change itself might introduce some new loopholes.
To patch the loophole exploited by the pulse illumination attack and defend this kind of blinding attacks thoroughly, we believe that the {\color{black}valid} method is to integrate the loophole into the security proof of QKD protocol.

\section{Conclusion}
We investigate the effectiveness of a photocurrent monitor as a countermeasure against the detector blinding attack in a single-photon detector module that is provided by an independent party. The testing results show that the single-photon detector with a photocurrent monitor is vulnerable to the pulse illumination attack. Via this attack, Eve can blind the single-photon detector in a certain period and fully control its detection output, keeping the reported photocurrent of the photocurrent monitor similar to that in the normal state and thus without alarming the monitor. We also perform the theoretical security analysis to show that for a real-life QKD system under pulse illumination attack, Alice and Bob may overestimate the secret key rate and leak the key to Eve in a certain distance range. This pulse illumination attack indicates that the security issues in the detection side {\color{black} might be} still serious, which should be further investigated. As this attack {\color{black}might} seriously threatens the practical security of QKD systems, pulse illumination attack should be a standard testing item for the systematic security evaluation of a QKD system.

We also provide more details on the photocurrent of a detector under the pulse illumination attack obtained from a white-box experiment on our homemade detector (see \cref{sec:countermeasure}), which may provide some ideas of countermeasures against the pulse illumination attack. However, patching only solves the problem in a short term. A more secure method is to model the practical single-photon detector in the security proof, if the non-MDI-QKD system would like to be immune to various blinding attacks in a long term.

\section*{Funding Information}
National Natural Science Foundation of China (Grants No. 61901483, No. 11674397, No. 61601476, and No. 61632021) and National Key Research and Development Program of China (Grant No. 2019QY0702).

\section*{Acknowledgments}

We thank Vadim Makarov for very useful discussions. Supporting from Greatwall Quantum Laboratory is also acknowledged.

\section*{Disclosures}

\noindent\textbf{Disclosures.} The authors declare no conflicts of interest.

redpajama_set_name: RedPajamaArXiv


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text:
Quadriceps autograft to treat Achilles Chronic tears: a simple surgical technique
Rafael Arriaza ORCID: orcid.org/0000-0003-1743-38091,3,
Raquel Gayoso1,
Emilio López-Vidriero2,
Jesús Aizpurúa1 &
Carlos Agrasar3
Chronic Achilles tendon tears could hinder patients and represent a challenge to surgeons. Although many different surgical techniques have been proposed for reconstruction of a neglected Achilles tendon rupture, there is no clear evidence to support one technique over the others, but the use of a technique that could allow for an "anatomical" reconstructions seems desirable.
The present paper describes a new anatomic Achilles tendon reconstruction for chronic tears, using a quadriceps tendon autograft as graft source, with PRP injected into the graft and the neighbor tissue, and fixation in a bone trough with a simple small fragments screw.
Autologous quadriceps tendon graft seems an excellent option, although -surprisingly- has received little attention until now.
Autologous Quadriceps tendon graft (in bone-tendon configuration) is a simple technique that could allow surgeons to reconstruct tissue defects in the Achilles tendon with non-expensive hardware.
Achilles tendon ruptures represent the most common acute tendon rupture in the human body, and frequently they are diagnosed solely based on clinical examination, but it is considered that up to 25 % of them can be misdiagnosed by the first clinician who examines the patient [1, 2]. Some of them can take more than 4–6 weeks to get correct diagnosis and treatment, and are considered as chronic, neglected or delayed in medical literature, and represent a challenging therapeutic problem due to the retraction and scarring of the tendon stumps, that create a gap that could be several centimeters long (Fig. 1a). Although there is no consensus regarding the specific time in which an acute tear becomes a chronic rupture, 4 weeks may be the most widely accepted interval [3, 4], though in fact, in some cases it is more important to note the resultant gap between the tendon stumps than the time elapsed since the rupture. Regardless of the lack of a precise chronological definition, neglected ruptures are characterized by the difficulty of achieving an end-to-end apposition of the tendon ends with plantar flexion of the foot during surgical reconstruction.
a and b MRI of a 72 year old patient, before surgery (9 months after Achilles tendon tear), and 8 months after surgery with autologous quadriceps tendon graft
In the past, several authors [5–7] recommended the use of an inverted superficial turn-down flap of the gastrocnemius fascia to cover the defect. Many other authors have used different tissues to bridge the tendon gap, from local tendons, such as flexor hallucis longus [8] or peroneus brevis tendon [9], to distant tendons, such as the semitendinosus [10] or gracilis tendons [11]. Although the use of the quadriceps tendon for the treatment of chronic Achilles tendon ruptures was first published in 1995 [12], we have found only anecdotic further references to such technique, without publications in English literature except to treat distal Achilles tendinosis [13] and, in fact, no consideration to this option was included in the revision of the history of graft options for neglected Achilles tendon ruptures published by the Cleveland Clinic team in 2008 [14].
Although platelet rich plasma (PRP) has been used with success in the treatment of acute Achilles tendon ruptures [15], a literature search yielded no results on its use for the treatment of chronic Achilles tendon ruptures, but the authors have been using PRP regularly in the last 10 years for the treatment of tendon injuries. and, to our knowledge, this is the first report on the results obtained with the use of an autograft and PRP in this difficult condition.
The present paper describes a new and simple surgical technique to obtain an anatomic Achilles tendon reconstruction, using a quadriceps tendon autograft as graft source, with PRP injected into the graft and the neighbor tissue, and fixation in a bone trough with a simple small fragments screw.
Preparation and patient positioning
The patient is positioned in lateral decubitus position, on the uninjured side, tilted ventrally. Either general or regional anesthesia could be used, and prophylactic antibiotic in injected before thigh tourniquet is inflated. The lower limb is prepped and draped free. By external hip rotation with both the hip and the knee flexed, the assistant keeps the limb in a position in which the that the patella is pointing to the ceiling.
Quadriceps tendon graft harvesting
A 5 cm skin incision is usually enough to delineate and harvest the bone-tendon quadriceps graft, with the standard technique. Usually, a 1 cm wide graft, with a 12 mm long bone plug and a 8–9 cm tendon length is obtained. After skin closure, the patient is rotated to ventral decubitus, which can easily be done without changing drapes. In this position, the Achilles tendon to be operated is now pointing to the ceiling, and the surgeon can work in a comfortable position.
Achilles tendon grafting
A standard paramedial Achilles incision, extended distally over the calcaneus tuberosity, is used. Careful dissection of the sural nerve is performed, taking into consideration the possibility that scar tissue or edema could be found surrounding it. After necrotic and scarred tendon tissue are debrided, a trough is created in the posterior aspect of the calcaneus, to accommodate the bone plug from the patella, and the plug is fitted into the trough and secured with a 3.5 mm cancellous screw (Fig. 2a and b). Next, the proximal and distal tendon stumps are longitudinally divided, and the quadriceps graft is sutured latero-laterally to them, keeping a tension that places the foot in slight (approximatelly 15°) equinus. Leukocyte-Poor Platelet-Rich Plasma is injected into the graft and the Achilles tendon stumps, and the wound is closed (Fig. 3).
a and b Creation of a bone trough in the posterior aspect of the calcaneus, and fixation of the bone plug with a small fragment cancellous screw
Injection of Leukocyte-Poor Platelet-Rich Plasma into the graft and the Achilles tendon stumps
After surgery, the patients are inmobilized with a below-knee cast for 3 weeks, and an orthesis with range of motion control is used thereafter, allowing free plantarward motion but limiting dorsiflexion to −20° for the next 2 weeks while allowing partial weight bearing. The orthesis is retired for night rest and physiotherapy, avoiding dorsiflexion above neutral until the 8th postoperative week.
The main finding of this study is that autologous quadriceps bone-tendon graft offers an excellent option for the repair of chronic Achilles tendon ruptures.
Quadriceps bone-tendon graft allows the repair of the Achilles tendon defect without any deleterious effect on neighbor structures, while offering an "anatomical" repair, as the bone plug can be placed in the tendon footprint at the posterior aspect of the calcaneus, avoiding modifications in the traction vector of the tendon. To the best of our knowledge, however, no surgical method using a quadriceps tendon graft fixed in a bone trough at the anatomical insertion site of the Achilles tendon at the calcaneus can currently be found in the literature. The reason for developing this new method was to bridge the tendon gap using a fairly simple procedure with a graft that is commonly used by sports surgeons, and to avoid the use of local tendons, as this option is not free of complications and possible functional imbalances [16].
Achilles tendon ruptures seem to have increased during the last two decades (in some areas, figures show a four-fold increase in incidence), probably due to the increase in the general population activity and sports participation [17]. A secondary consequence is an increase in the number of Achilles tendon ruptures not diagnosed properly during the initial medical visit, and also the increased number of patients with complications from the treatment -either surgical or conservative- employed to treat those ruptures. Those complications include re-ruptures, infections and tissue necrosis that could require further surgical procedures to correct the residual defect in the tendon, making it mandatory to use some form of graft tissue to bridge the defects [18]. Several surgical techniques have been proposed for reconstruction of a neglected Achilles tendon rupture, although there is no clear evidence to support one technique over the others, as the ultimate goal of the surgical treatment is to regain enough plantar flexion power in the ankle, and most techniques seem to reach this goal. In this sense, autologous quadriceps tendon graft seems an excellent option, although -surprisingly- has received little attention until now [12]. It is well known that quadriceps tendon autograft represents a reliable option for the treatment of several sports injuries, including ACL tears, and its use has seen a renewed interest, due in part to its excellent mechanical properties, the solid fixation that can be obtained using its bone plug if harvested as a bone-tendon unit, and the low morbidity associated with this procedure [19].
One of the most populat grafts for chronic Achilles tendon reconstruction is the FHL tendon, due to its proximity to the Achilles tendon, but its average lenght when harvested through a posterior incision is only 5.16 cm, which could prove insufficient to cover a higher defect [20], and for that reason, does not offer any special advantage to the use of the quadriceps tendon graft, which is usually longer.
After surgery, the foot is placed in equinus position to reduce the tension in the graft tissue and to increase skin vascularization, in order to minimize the risk of skin necrosis [21]. The use of PRP injection into the margins of the tendon graft and the host tissue was done to promote tissue healing, as some studies have shown an increase in the strength of the Achilles tendon in rats after PRP injection [22], and a faster recovery after PRP injection associated with surgical repair of the Achilles tendon in athletes [15]. Although, to our knowledge, this procedure has not been published in association with the surgical repair of chronic Achilles tendon tears, we opted to use the PRP injection of the repair site as the biologic environment created by the surgical procedure seems similar to the one of an ACL repair with an autologous graft tissue, in which the addition of PRP has been shown by some authors to promote an early integration and maturation of the graft [23]. We do acknowledge that there is still not enough scientific evidence to support the regular use of PRP in these surgical procedures, and a future randomized study might give very valuable information regarding its importance in the results obtained with the quadriceps tendon graft in cases of chronic Achilles tendon tears with marked retraction.
Limitations of this procedure lie basically in the distance of the tendon gap from the calcaneus: if is located more than 5–6 cm away from the calcaneus, the quadriceps graft might not have length enough to bridge it, in which case should opt for a different surgical procedures, as the ones recently described with a free tendon graft, as suggested by Sarzaeem [24] and Maffulli [25], a scar tissue repair and FHL augmentation, as proposed by Lee [26], or a free gastrocnemius aponeurosis flap, as proposed by Nilsson-Helander [10]. Also, this is a technical note, not presenting clinical and radiological follow-up data. In order to demonstrate the clinical significance and safety of this technique, clinical and radiological follow-up studies will be needed. A case series will be presented shortly when operated patients will have reached a significant follow-up.
Autologous Quadriceps tendon graft (in bone-tendon configuration) is a simple technique that could allow surgeons to reconstruct tissue defects in the Achilles tendon. It could be used not only in cases of chronic or neglected Achilles tendon ruptures, but also in cases of surgical complications (as deep infections or Achilles tendon necrosis), without altering the function of the neighbor structures, nor shortening the myotendinous triceps surae unit.
Written informed consent was obtained from the patient for the publication of this report and any accompanying images.
PRP:
Platelet-rich plasma
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Nilsson-Helander K, Sward L, Silbernagel KG, Thomeé R, Eriksson BI, Karlsson J. A new surgical method to treat chronic ruptures and reruptures of the Achilles tendon. Knee Surg Sports Traumatol Arthrosc. 2008;16:614–20.
Maffulli N, Leadbetter WB. Free gracilis tendon graft in chronic tears of the Achilles tendon. Clin J Sport Med. 2005;15:56–61.
Besse JL, Lerat JL, Moyen B, Vincent P, Brunet-Guedj E. Distal reconstruction of the Achilles tendon with a bone-tendon graft from extensor system of the knee. Rev Chir Orthop Reparatrice Appar Mot. 1995;81(5):453–7.
Philippot C, Wegrzyn J, Grosclaude S, Besse JC. Repair of insertional Achilles tendinosis with a bone-quadriceps tendon graft. Foot Ankle Int. 2010;31(9):802–6.
Gove JR, Hardy MA. Autograft, allograft and xenograft options in the treatment of neglected Achilles tendon ruptures: a historical review with illustration of surgical repair. Foot Ankle J. 2008;1(5):1–10.
Sánchez M, Anitua E, Azofra J, Andía I, Padilla S, Mujika I. Comparison of surgically repaired Achilles tendon tears using platelet-rich fibrin matrices. Am J Sports Med. 2007;35(2):245–51.
Richardson DR, Willers J, Cohen BE, Davis WH, Jones CP, Anderson RB. Evaluation of the hallux morbidity of single-incision flexor hallucis longus tendon transfer. Foot Ankle Int. 2009;30:627–30.
Pajala A, Kangas J, Ohtonen P, Leppilahti J. Rerupture and deep infection following treatment of total Achilles tendon rupture. J Bone Joint Surg Am. 2002;84-A:2016–21.
Bergkvist D, Åström I, Josefsson PO, Dahlberg LE. Acute Achilles tendon rupture: a questionnaire follow-up of 487 patients. J Bone Joint Surg Am. 2012;94-A:1229–33.
DeAngelis JP, Fulkerson JP. Quadriceps tendon–a reliable alternative for reconstruction of the anterior cruciate ligament. Clin Sports Med. 2007;26:587–96.
Tashjian RZ, Hur J, Sullivan RF, Campbell JT, DiGiovanni CW. Flexor hallucis longus transfer for repair of chronic Achilles tendinopathy. Foot Ankle Int. 2003;24(9):673–6.
Poynton AR, O'Rourke K. An analysis of skin perfusion over the Achilles tendon in varying degrees of plantarflexion. Foot Ankle Int. 2001;22:572–4.
Kaux JF, Drion PV, Colige A, Pascon F, Libertiaux V, et al. Effects of platelet-rich plasma (PRP) on the healing of Achilles tendons of rats. Wound Repair Regen. 2012;20:748–56.
Vogrin M, Rupreht M, Dinevski D, Haspl M, Kuhta M, et al. Effects of a platelet gel on early graft revascularization after anterior cruciate ligament reconstruction: a prospective, randomized, double-blind, clinical trial. Eur Surg Res. 2010;45:77–85.
Sarzaeem MM, Lemraski MMB, Safdari F. Chronic Achilles tendon rupture reconstruction using a free semitendinosus tendon graft transfer. Knee Surg Sports Traumatol Arthrosc. 2012;20:1386–91.
Maffulli N, Del Buono A, Spiezia F, Maffulli GD, Longo UG, Denaro V. Less-invasive semitendinosus tendon graft augmentation for the reconstruction of chronic tears of the Achilles tendon. Am J Sports Med. 2013;41:865–71.
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Instituto Médico Arriaza y Asociados, Calle Enrique Mariñas, 32, 15008, La Coruña, Spain
Rafael Arriaza, Raquel Gayoso & Jesús Aizpurúa
International Sports Medicine Clinic, Calle Arjona, 10, 41001, Sevilla, Spain
Emilio López-Vidriero
Cátedra de Traumatología del Deporte HM, Universidade da Coruña, Avenida Che Guevara 121, Oleiros, 15179, A Coruña, Spain
Rafael Arriaza & Carlos Agrasar
Rafael Arriaza
Raquel Gayoso
Jesús Aizpurúa
Carlos Agrasar
Correspondence to Rafael Arriaza.
RA devised the surgical technique and wrote the manuscript. RG, CA and JA made substantial contributions to the technique. EL-V critically revised the manuscript and produced the final version. All authors read and approved the final manuscript.
Arriaza, R., Gayoso, R., López-Vidriero, E. et al. Quadriceps autograft to treat Achilles Chronic tears: a simple surgical technique. BMC Musculoskelet Disord 17, 116 (2016). https://doi.org/10.1186/s12891-016-0967-1
Chronic Achilles tendon rupture
Surgical reconstruction
Quadriceps autograft

redpajama_set_name: RedPajamaCommonCrawl


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Have you recently looked for a dog walker in Wrexham? It can be pretty overwhelming with all of the options available. Instead of looking for kennels in Wrexham, have you considered finding a lovely local friend for your pup instead? Each and every one of our borrowers look after dogs simply for the love of dogs rather than to get paid which is pretty pawsome!
Do you love dogs but can't have one of your own? Why not borrow a dog in Wrexham instead? There are so many pups that would love an extra walk, belly rub or game of fetch. Why not create a free profile and see if there's a pawfect match for you just around the corner.
"Myself, my Collie cross, Bo, and our borrower, Ceri, couldn't be happier, so thank you so much for the wonderful service and unexpected benefits! I was left with Bo when a domestic change occurred in life. Enter BorrowMyDoggy! I met Ceri and her daughter Amy last year - fast forward a year, and Bo is now very much a part of their family, too." - Bo's owner, Nick.
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Whether you're new to the area or are looking for some enjoyable dog walks in Wrexham you're in luck as there are lots to choose from.
This is a great place to visit if you are walking a dog in Wrexham. Whether your pup loves a game of fetch, enjoys exploring woodland trails, or loves to swim, Ty Mawr Country Park has you covered. There are also some great views of the Dee valley and the chance to see lots of animals including llamas and pigs. Why not take a picnic and really make a day of it? Refreshments are also available on route if you want to stop for a bite to eat.
Another great park to visit if you're looking after someone's dog in Wrexham is Alyn Waters Country Park. Pups can indulge in a spot of swimming and two legged friends can enjoy the lovely scenery and wildlife. There is also a cafe where you can grab a drink, pups aren't allowed in but food and drinks can be taken away.
Although small, Acton Park still makes for a lovely place to walk a dog in Wrexham. Take in the pawsome scenery, visit the japanese gardens and maybe even feed the ducks. Complete with picnic tables and a mixture of hilly and flat paths, there are a number of routes to follow which are sure to keep you and your four legged friend busy for a few hours.
This world heritage site is over 250 years old and offers amazing views from the towpath. Popular with dog walkers, cyclists and families, this is a walk for the whole family, there is also lovely cafe at the end of the walk and a nice pub where you can grab something to eat after your walk.
The pawfect place to stop for lunch after walking someone's dog in Wrexham. Your pup will be welcomed with open arms and provided with water while you tuck into some delicious home cooked food. Doggy diners have their own separate area and staff are happy to welcome pups inside whether they are muddy and wet, or dry and fluffy!
Pups will be treated to water bowls and dog biscuits on arrival so it's clear to see why this place is popular with both locals and visitors. Pups are welcome to dine with you inside and there is a great selection of food and drink options for two legged friends too!
If you're a dog sitter in Wrexham looking for a lovely friendly place to stop for lunch then this is a great option. They have a big jar of tasty treats on the bar if your pup has been pawticularly well behaved. As well as having a great menu, they also have a dog friendly camping site with lots of pup friendly open fields, if you wanted to extend your stay.
Filled with quaint furnishings and a lovely roaring log fire, this is a great little gastropub which also boasts a pretty beer garden with views of a small lake and some lovely lunch options. Pups will be given lots of fuss as well as water and some wagtastic treats. If you're looking for somewhere quiet to enjoy the beautiful surroundings with your furry friend then this is a great option.
It's always nice to know where your nearest vet is located when looking after someone's dog in Wrexham. Offering a range of services from pet protection and insurance to emergency care as well as standard consultations. Appointments can be booked over the phone or online.
Offering services from microchipping, vaccinations to neutering and general pet care advice, this vet is open Monday - Sunday so you can be sure that your pup is in good hands. They also run a obesity clinic to help with pet weight gain, as well as a senior dog and cat clinic to help keep older pets in tip top condition.
Pawsibly the most famous pet shop, Pets at Home is a great place to visit if your pup has been particularly well behaved. Whether you're looking for a new harness and lead or would like a toy or some treats, Pets at Home has you covered. Your pup is also welcome to join you in store so he can sniff out his own treat which is pretty pawsome!
Open seven days a week, this independent pet shop stocks a range of food, treats bedding accessories, cages and lots more. You can also get your pup groomed while you're here so you can be sure that your pup is looking as wagtastic as possible!


On Saturday in Carmichael, Jesuit and Oak Ridge offered a glimpse of how exciting the upcoming playoffs might be. Jesuit looked all-world in the first half, stampeding for long touchdown runs with Beau Bisharat and Ben Parietti to lead No. 3 Oak Ridge 42-21 at the half.
Trojans coaches, scheming under a shade tree, scrambled to come up with a defensive plan to stall the Marauders' run game. They found one, moving ends and linebackers around like chess pieces, and used it in the second half. The Trojans' thinking: It either works, or it backfires and we all walk back to El Dorado Hills with long faces.
Oak Ridge charged back behind the revamped defense headed by linebacker Trent Buenzli, who has a 4.6 grade-point average, a tackling machine in Thomas Mahlman and sophomore quarterbackIan Book, who tossed three of his five touchdown passes in the second half. The defense had an overtime stop to set up Adam Walter's game-winning 20-yard field goal for a 45-42 victory, punctuating the second-half shutout.
While Oak Ridge rejoiced, Jesuit looked sick.
Both teams advance to the Sac-Joaquin Section Division I playoffs. Jesuit knows it can storm past foes if it plays the way it did in Saturday's first half or be silenced if it plays the way it did in the second.
Oak Ridge will bottle its second-half effort at Jesuit as momentum for a potential repeat run to the title game, and all teams understand no lead is safe.
Who says that during a pressure cooker? Only a teenager who understands this game is supposed to be all about fun.
After games, Oak Ridge coach Eric Cavaliere seeks out his parents, thanking them for the support and inviting input. His father, Bill, regardless of outcome, is quick to point out holding calls or a dropped pass before an assuring handshake and hug. His mother offers a different view.
Prep football also allows coaches to see players develop and grow in a matter of months. Jesuit wasn't sure how quarterback Jason Elenberger and the Marauders' backfield would adjust to the veer offense. They have mostly flourished, with Elenberger setting a school rushing record for quarterbacks.
In the summer, Oak Ridge wasn't sure who would play quarterback. It went with Book, who works behind a revamped offensive line that includes his older brother, Nolan. Jacob Sipes, who lost the quarterback battle to Book, has emerged as one of the section's most versatile players at wide receiver, defensive back and punter.
The other appeal of high school football is connecting the generation gap. Players come and go, but memories linger and draw the alumni back. Bisharat's father, Charlie, was a record-setting running back for Jesuit in the late 1970s. Beau's cousin, Haitham Bisharat, was a starting right tackle for the Marauders' first section title team in 1995.
A Trojans observer lately has been Jon DeVille, a star quarterback at Oak Ridge in the early 1990s who now works in law enforcement in El Dorado County.
"Amazing what these kids can do these days," DeVille marveled.
And Cavaliere and assistant coach Mark Watson compete in honor of the program's founding coach, Jack Harnden. He died last summer after a battle with lymphoma. His wife, Karen, still attends games with the Watson family and generally sits at the edge of her seat because she cannot begin to predict what will transpire.
"During the half, we decided to install a defense we haven't used in a good five years or so, and we had our scout offense line up right there and installed it on the spot," Cavaliere said. "This year's team is the only one I can think of that we've had that could get away with that, and it's a very smart group. What a difference. The defense was a Jack Harnden special from the good old days.


text:
The Best Punta Cana Resorts for Families With Kids
Chris Olvera, Leaf Group
(Photo: Jupiterimages/Photos.com/Getty Images )
All-Inclusive Family Resorts in the Dominican Republic
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Resorts in Punta Cana aren't just about romantic getaways. This vacation spot in the Dominican Republic has resorts for the whole family, even small children. Of course, kids of all ages will love the beaches and swimming pools, but these Punta Cana resorts also offer special programs for children from just a few months to 17 years old.
The Children's Circus School at Club Med Punta Cana teaches kids Big Top skills like juggling, clowning and riding a unicycle. The school also offers tightrope walking, trampoline bouncing and a safe ride on the flying trapeze. Mini Club Med, for kids 4 to 10, features a clubhouse with toys and games, plus supervised meals and pool time.
Apt. Postal 106, Higuey
clubmed.us
Paradisus Punta Cana Resort
The Paradisus Punta Cana Resort is an all-inclusive hotel that welcomes arriving families with its Family Concierge. This service provides a private check-in area, a beach kit with a hat and T-shirt, walkie-talkies, and family activities and sports. An Adventure and Action Park features batting cages, a climbing wall, archery and bicycle rentals. With the park, two kids pools and the beach, you should be all set.
Playa de Bavaro, Higuey
paradisuspuntacana.travel
Dreams Punta Cana Resort & Spa
The Explorer's Club at Dreams Punta Cana Resort & Spa is available to guests with "Unlimited Luxury" privileges. The supervised club is for kids ages 3 to 12, but the resort also offers an Infant Club with a pool, nap area, TV and indoor/outdoor playground. The Explorer's Club features activities such as pony rides, treasure hunts and a Dino Dig. Other activities include a water slide, playground, indoor game room and video games.
Dreams Punta Cana Resort & Spa
Playas Uvero Alto
Provincia La Altagracia
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Puntacana Resort & Club
The kids will have plenty to do in the Puntacana Resort & Club's organized children's program. The Carousel Activities Program is for kids ages 4 to 12 and includes boat rides, painting classes and sports activities. The resort also offers less structured fun, with pony rides, kids pools, bicycle rentals (tricycles too) and even a mini zoo.
Punta Cana, Higuey
puntacana.com
The Flintstones rule at Melia Caribe Tropical in Punta Cana. Kids get the special treatment when Fred and Dino greet them at check-in. The Flintstones activities keep on coming with Betty's Kitchen, the Yabba-Dabba-Doo Bazaar, Fun Park, Stone Lake and Rocadventure. Kids can also join activity clubs: Baby Rock Club (4 months to 4 years), Bamm-Bamm Club (5 to 8) and the Cool Club (9 to 13).
meliacaribetropical.com
Tropical Princess Beach Resort & Spa
If you're going the all-inclusive route in Punta Cana, keep the Tropical Princess Beach Resort & Spa in mind. For those not old enough to enjoy the included libations, there's a club for teens ages 13 to 17, offering billiards and other table games. There's another club for kids ages 4 to 12. The resort has four pools, including a kids pool, plus tennis courts, minigolf, bicycles and archery. And don't forget the beach.
Tropical Princess Beach Resort & Spa
Playas de Bavaro, Higuey
princess-hotels.com
Based out of Brookfield, Ill., Chris Olvera is a writer and editor with more than 15 years experience. He was editor of Manufactured Home Merchandiser for 10 years. Chris also was an editor for CSP Magazine and of the Villa Park Review. He is a graduate of Columbia College in Chicago.
Attribution: Alexrk2; License: Creative Commons Attribution-Share Alike 3.0 Unported license
Olvera, Chris. "The Best Punta Cana Resorts for Families With Kids." Travel Tips - USA Today, https://traveltips.usatoday.com/punta-cana-resorts-families-kids-20389.html. Accessed 15 July 2019.
Olvera, Chris. (n.d.). The Best Punta Cana Resorts for Families With Kids. Travel Tips - USA Today. Retrieved from https://traveltips.usatoday.com/punta-cana-resorts-families-kids-20389.html
Olvera, Chris. "The Best Punta Cana Resorts for Families With Kids" accessed July 15, 2019. https://traveltips.usatoday.com/punta-cana-resorts-families-kids-20389.html
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Indian startups raise a record $3.9 billion so far in 2019
Deal-making has also broadened, across companies and sectors, moving away from a few large companies such as Ola, Paytm and Flipkart
The data defines venture capital investments as seed, or very early investments, to Series F deals in companies
Startups in India have raised a record $3.9 billion from venture capitalists in the six months ended 30 June, as the world's biggest investors doubled down on their bets in the country buoyed by the Flipkart-Walmart deal last year.
The investments this year across 292 deals is a 44.4% jump from the $2.7 billion received by domestic startups in the first half of 2018, showed data from Venture Intelligence, a startup data tracker.
The investments in 2019 are also comparable to the full-year investments of $4.2 billion and $4.3 billion in 2016 and 2017, respectively, indicating the surge of capital allocation in the past six months.
The data defines venture capital investments as seed, or very early investments, to Series F deals in companies that are less than 10 years old.
Terming 2018 a turning point for the market, Sandeep Murthy, managing partner at Lightbox Ventures, said "many companies that have been quietly building and solving truly unique problems have achieved scale".
"They are now being rewarded with capital that will allow these businesses to continue to grow… in many cases profitably," said Murthy, whose fund is an early backer of online furniture rental startup Furlenco and cloud kitchen firm Rebel Foods, best known for its Faasos brand.
While consumer internet firms have been continuing to raise large amounts of capital, business-to-business (B2B) companies in sectors such as logistics, software and marketplaces are also raising money now.
Murthy said "2019 has also been about the emergence of Tier II and III cities and B2B models, both of which had been historically underinvested in".
"Tiger Global has clearly indicated their interest in the B2B space, while Chinese investors seem to be pushing deeper into emerging cities across India," he said.
Recent deals, especially the $16 billion acquisition of India's online retailer Flipkart by US retail giant Walmart last year, lured more investors to India. That deal saw investors in Flipkart make 1.5-10 times their investments, with billion-dollar exits for venture capital firm Accel Partners, Japan's SoftBank Group Corp., South Africa's Naspers and US-based Tiger Global Management Llc.
"Post the Flipkart exit, there is an increased confidence in the India market that you can get large outcomes and get liquidity. Till then there were always questions on whether money from India will come back or not. Flipkart investors made a healthy return and are investing again," said Mukul Arora, partner at SAIF Partners, an early backer of Paytm, BookMyShow and Swiggy, among others.
"We started seeing investments in late-stage tech becoming very aggressive, following which growth stage, series B and C deal-making also got aggressive. Now that is rubbing off into early-stage deals as well," said Arora.
Mint reported on 2 June that startup funding has seen a late-stage boom, with more deals of $100 million or above in the first five months of this year than in the first half of the last two years.
Deal-making has also broadened, across companies and sectors, moving away from a few large companies such as Ola, Paytm and Flipkart that used to top fundraising charts every year.
To be sure, valuations have risen in recent times, making some investors cautious, but most have been able to see gains stemming from firms despite higher valuations.
"I do believe valuations have gone up, not just at the top end of the market for large rounds, but also at the earlier stages… As an investor, I would rather pay a slightly higher price for a higher quality business than get a bargain valuation for an inefficient company," said Murthy at Lightbox.
Coatue may lead $120 mn funding in Faasos parent
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June 30, 2019 Tanya Jain Tags: ENTREPRENEUR, eustan ventures, fundraise, startup funding Categories:


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Interpretation of Sura Cow - Verse 221
:Sayyid Kamal Faghih Imani
221. " And do not marry idolater women until they believe, and a believing maid is definitely preferable to an idolater (free) woman even though she may please you. Nor give (your women) in marriage to idolater men until they believe; and certainly a believing servant is preferable to an idolater (free man) , though he may please you. Those invite to the Fire while Allah invites to paradise and forgiveness by His Will, and He makes clear His Signs to people, so that they may take heed."
Occasion of Revelation
Once there came a man into Mecca by the name of Marthad. He was a brave man who had converted to Islam. He occasionally met " 'Anagh ", the beautiful woman whom he was acquainted with formerly, at the time of Ignorance. She invited him to sinful actions as before, but Marthad, who had become a Muslim, did not accept her wish. Hence, the woman asked him to marry her. Marthad replied that it was contingent on the permission of the Prophet (p.b.u.h.) . Then, after performing his affairs, he returned to Medina and told the Prophet (p.b.u.h.) about the matter. So, this verse was revealed and stated that the idol-worshippers and pagan women are not eligible to be married by Muslim men.
The term /nikah/ in Arabic philology means: ' matrimony, wedlock, and marriage '. Islam has considered a number of conditions for the wife that a man wants to select. These conditions are identified in Islam because this religion takes the matrimonial life important for the sake of the assured heritable effects upon offspring, and, also, for the sake of the training issues of the family environment over the fate of the children. It says, for example, that a pagan woman is not suitable to be married by a Muslim. Supposing that such a woman be chosen for marriage, the resulting children will naturally obtain her spiritualities and qualities under the principle of heritage, and after birth, if they trained by that mother, (whereas it is often thus) , these children may have an abominable end. That is why the Holy Qur'an, in this verse, has explicitly prohibited marriage with the women who are infidel or idol-worshippers.
" And do not marry idolater women until they believe, and a believing maid is definitely preferable to an idolater (free) woman even though she may please you. ... "
In addition to that, if pagans, who are counted foreigners in an Islamic society, penetrate into the houses of Muslims by means of marriage, that society will be inflicted with disorder and interior enemies. In such a situation the different rows and categories therein are not recognized from each other. Hence, the Qur'an, hereby, tells them not to marry with that group of women. However, Islam has not closed all the doors absolutely to them. Therefore, in order to use their sexual tendency towards their felicity, the Qur'an says:
" ... Nor give (your women) in marriage to idolater men until they believe; and certainly a believing servant is preferable to an idolater (free man) , though he may please you. ..." Similar to the statement at the threshold of the verse that prohibits men from marrying idolatress or infidel women, in this part of the verse, giving girls and women in marriage to infidels and idolater men is prohibited, too. And, similar to the idea that the believing maids are more eligible to marry with than the free idolater women even with admirable beauty or wealth, the believing servants and slaves are more eligible to marry with than the handsome men who are apparently of dignity but disbelieving. In fact, the wedlock of believing women with disbelieving men is forbidden while they are infidels; but there is no sin in marrying them when they accept the truth and believe. This is the very way of return which was also pointed out at the beginning of the verse. In the subsequent sentence, the reason of the prohibition for the wedlock of believing ones with idolaters and infidels, men and women, is expressed:
" ... Those invite to the Fire while Allah invites to Paradise and forgiveness by His Will, ... " The prohibition of marriage with an idolater is for the reason that they call their companions towards idolatry and some disgraceful manners. Their behaviour, of course, originates from idolism especially when this companionship is via matrimony whose intensity of mutual effect is deeper and more impressive. The fruit of this conduct is the blazing Fire of Hell.
Briefly speaking, acquaintance with them, particularly through the way of marriage, is inacquaintance with Allah; and approaching them is, indeed, keeping aloof from the Lord.
The believers, unlike that group, because of belief and high human qualities resulting from their true Faith, call their companions to the Truth and excellence. The fate of this manner is Paradise and the forgiveness of Allah. In this occasion, regarding the close and sincere relation that the true believers have with Allah, He has applied His own appellation instead of using 'believers' and has said: " ... Allah invites to Paradise and forgiveness by His Will, ... " Commenting on the last part of this holy verse, the author of Atyab-ul-Bayan says: 107 " Allah (s.w.t) makes His Signs clear to people to be guided and consequently, they haply take heed. When they recognize the difference between obedience and disobedience, they may avoid sin and follow worship. These Signs are irrespective of revealed prescripts, applicable duties, and ethical instructions; or the verses of macrocosm and microcosm which lead the servants towards the path of felicity and salvation so that they are rescued from the calamities of this world and those of the next world." "... and He makes clear His signs to people, so that they may take heed."
107. Atyab-ul-Bayan, vol. 2, p. 441
Adapted from the book: "The Light of The Quran - Interpretation of Sura Al-Baqarah (The Cow)" by: "Sayyid Kamal Faghih Imani and A Group of Muslim Scholars"
An Outline of Law from a Quranic Perspective
Examination of the Qur'anic verse regarding self-destruction
The Holy Qur'an and love of the Ahl al-Bayt (as)
The Qur'ān & the Sharā`ah
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The 170th session of the Florida Annual Conference will be held next week on Thursday through Friday, June 14-16, 2012 at the Lakeland Center. On Wednesday afternoon at 2:00 p.m. there will be special workshops to help leaders strengthen the ministries of their local churches. On Thurday the laity and clergy sessions will begin at 10:00 a.m., and the opening plenary of the conference will begin at 1:30 p.m.
The theme of our conference will be Transforming the World by Being United in Christ. A lack of unity among Christians makes a wreck of Christians' witness to the world since our witness is that God has reconciled the world in Jesus Christ. Yet unity is not an ideal; it is a task. It is not something that can be taken for granted, but requires firm committment by the grace of God. The problem of division is directly related to our need for redemption from sin, for our individualism and divisions are the signs of our original sin of being fallen from God's presence and purposes. Given the roots of division in the power of sin, it is not surprising that the task of being united is one of the more difficult and perilous of all Christian endeavors. Being united is an on-going challenge for a local congregation. As the task of unity expands to include congregations in a conference, or conferences within one church, or the many churches, then it becomes exceedingly complex.
To help us get some perspective, I have invited Dr. Michael Kinnamon to speak to us. A Disciples of Christ minister, he is the former head of the National Council of Churches of Christ in America, and I think he is the most knowledgeable person in our country on ecumenism. To celebrate our full communion with the African Methodist Episcopal Church and the Evangelical Lutheran Church in America, I have invited Bishop John White, the ecumenical officer of the AME Church, to preach at the Communion service on Thursday night and Bishop Ed Benoway of the Florida-Bahamas Synod of the ELCA to preach at the Ordination service on Friday night. We are also grateful to have with us President Gesner Paul of the Methodist Church in Haiti for the signing of a new covenant between our conference and their district. The Rev. Russell Meyer, head of the Florida Council of Churches, will also be present to greet us.
Over the years I have greatly reduced the amount of talk that takes place during the plenary sessions of the annual conference. The only reports which are presented orally are those which require approval of the conference or pertain to important common ministries of the conference. It is assumed that it is not necessary to discuss every important facet of the conference's ministry at every annual conference. Generally this year there will be oral presentations of the Strategic Leadership Team, the Bishop's Capital Campaign, and the administrative committees of the conference pertaining to real property, insurance, pensions and health benefits, and the annual conference budget. The Strategic Leadership Team will present a plan for the conference on Thursday afternoon.
By the end of this conference I will have presided over twelve sessions of the Florida Annual Conference. Melba and I want to thank you for accepting us to live and work among you over the past eleven years and several months. I look forward to being with you one last time as your presiding bishop.