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n Saturday I headed to Oxford for a one-day meeting about big science in physics that was organised by the St Cross Centre for the History and Philosophy of Physics at Oxford University. Held in the Martin Wood Lecture theatre at the Department of Physics, the meeting covered the past, present and future of big science. The audience was made up of academics as well as the general public, with 200 people having registered to attend.

First up was Helge Kragh from the Niels Bohr Institute in Copenhagen, who gave a fascinating talk about what we define as big science and how that term has changed over the past century. Kragh’s focus was on the Manhattan atomic-bomb project and what followed regarding the development of large particle accelerators.

Continuing the particle-physics theme was Isabelle Wingerter-Seez from the Laboratoire d’Annecy-le-Vieux de Physique des Particules, which belongs to the French National Centre for Scientific Research, who spoke about the beginnings of CERN and the discovery of the Higgs boson in 2012 at the lab’s Large Hadron Collider.

Frank Close from Oxford University
Leading by example: going green in the lab

One common theme in questions from the audience (of which there were many) was how big-science facilities could become, well, more green. There are some facilities that are working towards this, notably the SESAME synchrotron in Jordan and the ESS, both of which use or will use renewable energy to power the accelerator complex.

But given that big science is getting bigger and ever-more important, energy sustainability needs to become a much greater consideration for those planning, designing and building these future facilities.

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Faculty Sections / Smart band-aid senses and treats bacterial infections
« on: February 26, 2020, 04:29:08 PM »
Antimicrobial resistance is a serious threat to global health, a phenomenon that is largely driven by incorrect treatment regimens, which result in misuse and overuse of antibiotics. Therefore, it is important to develop rapid and cheap ways of detecting bacteria, along with their sensitivity or resistance to antibiotics. This would allow rapid diagnosis of infections, tailored prescription of drugs and, in turn, a more informed and sustainable use of antibiotics.

In response to these demands, a team of researchers from the Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, has developed a paper-based adhesive plaster, or band-aid, based on a “sense and treat” approach. The plaster senses the presence of bacteria by changing its colour and releases antibiotics when necessary. In addition, the paper is able to distinguish between certain drug-susceptible and drug-resistant bacteria, therefore informing the best disinfection strategy (ACS Cent. Sci. 10.1021/acscentsci.9b01104).

The plaster works like a traffic light. It appears green under normal conditions, while it turns yellow in the presence of drug-sensitive bacteria and automatically releases antibiotics to kill them. If the bacteria are drug-resistant, the paper becomes red and photodynamic therapy (PDT) can be used instead. PDT is performed by shining 628 nm light onto the plaster, which induces the production of reactive oxygen species that kill or weaken the resistant bacteria.

Ad-hoc chemistry
The plaster exploits chemical compounds that change colour in the presence of bacteria. In particular, the material is soaked in bromothymol blue, a pH indicator that turns from green to yellow when exposed to the acidic environment created by bacterial metabolism. The paper also contains a pH-sensitive metal–organic framework, a compound that acts as a cage containing antibiotic molecules. Upon increased acidity, the framework breaks open and the encapsulated antibiotic is released.

A wide class of resistant bacteria produce β-lactamase, an enzyme that destroys certain types of antibiotic molecules. In response to this, the plaster is also equipped with nitrocefin, an antibiotic that shows a distinct colour change from yellow to red when interacting with β-lactamase, hence signalling the presence of drug-resistant bacteria and the need for a therapy other than antibiotics.

Based on these principles, the researchers have shown that the plaster accelerates wound healing in mice infected with both sensitive and resistant bacteria. They monitored the status of the wound over three days, and clearly observed improved tissue regeneration following the disinfecting action of either antibiotics or PDT.

The team also demonstrated the potential of the paper device in a fruit preservation model, in which it was attached onto an infected tomato that successfully recovered after three days of sensing and treatment.

The future of diagnosis and treatment
The team’s novel adhesive plaster offers great potential for the future of diagnosing and treating wound infections. It is cheap, easy to use, and effective against certain types of bacterial infections. Extending the method to practical and point-of-care applications will be the next challenge towards widespread use. Technologies like this could contribute significantly to the fight against antimicrobial resistance.

Computer System, Programming and Simulation / Skin Depth Calculator
« on: February 25, 2020, 05:15:37 PM »
The skin effect is a phenomenon whereby alternating electric current does not flow uniformly with respect to the cross-section of a conductive element, such as a wire. The current density is highest near the surface of the conductor and decreases exponentially as distance from the surface increases.

"Skin depth" refers to the point at which the current density reaches approximately 37% of its value at the surface of the conductor. Calculating skin depth requires the frequency of the AC signal and the resistivity and relative permeability of the conductive material. To use this calculator, just select the material type and enter the signal frequency. The resistivity and relative permeability of the chosen material will be automatically given.

Applications of Skin Depth
Skin depth is a convenient way to identify the region of the conductor in which the majority of current will flow. It is unnecessary (or in some cases wasteful) to use a wire with a radius that is significantly larger than the skin depth, because most of the current flows in the skin-depth region regardless of the size of the conductor.

The concept of skin depth might be better appreciated with the help of a real-world example. Consider RF signals for WiFi or Bluetooth, which operate at 2.4 GHz. Using the calculator, we see that the skin depth with a copper conductor is 1.331 micrometers. This means that even with a very thin (e.g., 30 AWG) wire, only a tiny fraction of the wire is carrying a significant amount of current.


This article offers an overview of the various component options for smart meter design and how they can improve the operation of the meters into which they are designed.

Utility meters―once hidden away in cobwebby basements and behind shrubbery―are now emerging as leading players in energy conservation efforts. The latest generation of “smart” electricity, water, and gas meters now offer both commercial and residential customers the information they need to use these resources more wisely. They also allow utility companies to monitor usage remotely, largely eliminating the need for manual readings; they can even make it possible to smooth grid power peaks spot tampering, leakage, excess temperatures, etc.

The switch from traditional electromechanical meters to smart meters presents a variety of challenges for meter designers as they strive to develop solutions that are compatible with Advanced Metering Infrastructure (AMI). This allows integrating smart meters into the fast-growing Internet of Things (IoT), which supports remote communication and fault detection. However, one thing that has remained the same is that the utility companies that install these meters need them to be robust enough to operate reliably for decades and provide accurate measurements over the course of their lifetimes. To do that, they must incorporate a growing array of circuit protection, sensing, and power control components.

Electrical Machine / Wearables and Trackers for Competitive Sports
« on: February 25, 2020, 05:13:05 PM »
These sports wearables and trackers are pushing how we track our performance on and off the field, and how engineers devise ever more svelte packaging and clever ways to improve ourselves.

Wearables have become an important part of our everyday lives as they allow us to not only look hip, but they have the ability to monitor multiple aspects of our health. In addition to tracking heart rate, pulse, and steps taken, they have the ability to make us better athletes. That means running faster, jumping higher, swinging harder, and improving your overall game no matter what it is. Here are a few that are pushing the boundaries of sports wearables and how they track our performance.

The PIQ multi-sport sensor unit. Courtesy of PIQ
PIQ offers a wearable multi-sport sensor that can be used for sports as varied as skiing, tennis, and golf. The PIQ and its sport-specific apps are clever enough to track parameters like forehand, backhand, overhead smash, volleys, and top-spin for tennis. The skiing app will track edge-to-edge speed, G-force, air time, and rotation. The golf app can analyze and help improve your swing by tracking swing path and club head speed.

Until this point, biosensors have never really been considered for use in consumer electronics. This is because the biosensor devices that existed were simply not sensitive enough and were far too expensive for the consumer market.

However, the new biosensor design created by the researchers at the Moscow Institute of Physics and Technology Center for Photonics and 2D Materials could increase detector sensitivity several times over while also dramatically reducing the price.

"A conventional biosensor incorporates a ring resonator and a waveguide positioned in the same plane," explained MIPT graduate student Kirill Voronin from the Laboratory of Nanooptics and Plasmonics, who came up with the idea used in the study. "We decided to separate the two elements and put them in two different planes, with the ring above the waveguide."

This, as the researchers call it, is a two-level sensor layout. It was achieved by depositing a thin film and etching it, which creates both a ring resonator and waveguide at the same time and resulted in a higher sensitivity. Although this two-level design is less convenient for manufacturing unique devices, it is cheaper for mass-producing sensors. More importantly, however, is that the new two-tier design resulted in sensitivity many times higher than current biosensors.

"We have positioned the strip waveguide under the resonator, in the bulk dielectric," said paper co-author Aleksey Arsenin, a leading researcher at the MIPT Laboratory of Nanooptics and Plasmonics. "The resonator, in turn, is at the interface between the dielectric substrate and the external environment. By optimizing the refractive indices of the two surrounding media, we achieve a significantly higher sensitivity."


A biosensor layout provided by the Moscow Institute of Physics and Technology.

A diagram layout of the biosensor used by Moscow Institute researchers. Image used courtesy of Kirill Voronin

Using Biosensors in Consumer Electronics
Biosensors are electrochemical devices that determine the composition of biological fluids. A blood glucose meter is a good example of biosensors and indeed is virtually the only example of a biosensor device currently available on the mass market.

However, many people are hopeful that advances in biosensor technology like those made by the research team at MIPT could pave the way for more consumer electronics that include them. Examples of consumer electronics could include smartphones, wearable health and exercise sensors, and household appliances that could analyse bodily fluids for applications such as identity verification, medical analysis, and diet planning.

According to Valentyn Volkov, head of the MIPT Center for Photonics and 2D Materials, the team’s development will take biosensors to a “qualitatively new level”. However, it is estimated that it will take two-to-three years to develop an industrial design based on the proposed technology.

Analog Devices Inc. ADPD4000/1 Multimodal Sensor Front End can stimulate up to eight LEDs and measure the return signal on up to eight separate current inputs. Twelve available time slots can enable 12 separate measurements per sampling period. The data output and functional configuration utilize an I2C interface on the ADPD4001 or a serial port interface (SPI) on the ADPD4000. The control circuitry includes flexible LED signaling and synchronous detection. The devices use a 1.8V analog core and 1.8V/3.3V compatible digital input/output (I/O).

8 input channels with multiple operation modes to accommodate the following measurements: PPG, ECG, EDA, impedance, and temperature
Dual channel processing with simultaneous sampling
12 programmable time slots for synchronized sensor measurements
Flexible input multiplexing to support differential and single-ended sensor measurements
8 LED drivers, 4 of which can be driven simultaneously
On-chip digital filtering
Flexible sampling rate from 0.004Hz to 9kHz using internal oscillators
SNR of transmit and receive signal chain: 90dB
Ambient light rejection: 60dB up to 1kHz
400mA total LED drive current
Total system power dissipation: 50µW (combined LED and AFE power), continuous PPG measurement at 75dB SNR, 25Hz ODR, 100nA/mA CTR
SPI and I2C communications supported
256-byte FIFO
Wearable health and fitness monitors: heart rate monitors (HRMs), heart rate variability (HRV), stress, blood pressure estimation, SpO2, hydration, body composition
Industrial monitoring: CO, CO2, smoke, and aerosol detection
Home patient monitoring

In their research, published in the journal Nano Energy, the Japanese researchers focused on energy from the movement of liquid and created a device capable of generating electricity from the movement of a liquid droplet. The device was fabricated using flexible thin films made from molybdenum disulfide (MoS2) instead of graphene as the generator’s active material. This makes it possible to generate over five volts from a single liquid droplet. In contrast, graphene’s output voltage is limited to 0.1 volts. This is not enough to power electronic devices.

"To use MoS2 for the generator, it was necessary to form a large-area single-layer MoS2 film on a plastic film. With conventional methods, however, it was difficult to grow MoS2 uniformly on a large-area substrate," says Professor Ohno of the Institute of Materials and Systems for Sustainability at Nagoya University.

"In our study, we succeeded in fabricating this form of MoS2 film by means of chemical vapor deposition using a sapphire substrate with molybdenum oxide (MoO3) and sulphur powders. We also used a polystyrene film as a bearing material for the MoS2 film, so that we were able to transfer the synthesized MoS2 film to the surface of the plastic film quite easily."

When water droplets slide down the device’s upper surface, electricity is generated from the natural energy that is produced and harvested.

Tracking environmental degradation can be difficult to achieve, especially in large, unpopulated areas. Speaking to the press association (PA), technology entrepreneur Ewan Kirk said that drones are one of the easiest ways to collect important data from these remote regions.

A system was already demonstrated last year where data from remote IoT devices is harvested by passing drones that feed it back to a central database once they return to their charging station.

They are also being used to remotely monitor animals in national parks in South Africa to help prevent poaching and collect data on migration patterns and during the wildfire crisis in September, Australian authorities used drones to drop self-igniting “dragon eggs” in an attempt to control the spread of the fire.

While drones are useful for collecting important data from remote regions, their practicality has been restricted by their efficiency and battery life. While longer-range unmanned aerial vehicles (UAV) do exist, they can be too expensive to deploy on a larger scale.

Speaking to PA, Kirk - who directs the Turner-Kirk Charitable Trust - said: “Climate change is undoubtedly the biggest issue facing us all and as we get to grips with tackling this issue I fundamentally believe the development and deployment of technology - including UAVs - has a critical role in our global response.

“In the fight against poaching, UAVs can be an incredibly valuable resource to authorities. For example, at over 7,000 square miles, the Kruger National Park in Africa is almost the same size as Wales and poaching can happen anywhere and at any time of the day or night.

“To effectively patrol this area, anti-poaching agencies need UAVs with long flight times and they need them to be cheap enough that they can have many of them flying simultaneously.”

He added he would like UAVs to be an essential tool at the fingertips of those environment agencies already helping in the fight against climate change.

“They will help them gather data much more quickly and fundamentally I believe technology enables world-leading experts to do their jobs even better,” Dr Kirk explained.

He concluded: “In the area of conservation, continuous monitoring of endangered animals by UAVs will enable authorities to identify potential threats and increase the response times for wardens to intercept and prevent any illegal activity.

“Using UAVs to effectively monitor vegetation and land over large areas will help scientists and researchers to create large data sets helping them understand how climate change is affecting some of the world’s most critical resources.”

The programme follows a £15,000 donation from Kirk and partner Patricia Turner. They will look at developing new ways to adapt existing drones on an inexpensive basis as well as studying novel aircraft configurations designed to minimise the energy requirements.

EEE / Seismic activity on Mars confirmed by Insight lander
« on: February 25, 2020, 02:11:45 PM »
irst landing in November 2018 in the Elysium Planitia region, Insight (pictured above) detected over 100 “Marsquakes” in its first year on the planet. However, there was some debate amongst scientists as to whether the vibrations detected were legitimate seismic activity or just Martian wind rattling its instruments.

Dr Bruce Barnerdt, InSight principal investigator and lead author on one of the studies, said: “We finally have, for the first time, established that Mars is a seismically active planet.”

The first so-called “Marsquake” was recorded by InSight’s onboard sensors in April 2019. Since then, it has detected more than 450 quivers, much smaller than anything that would be felt on Earth.

Two of the quakes were found to emanate from a geologically active area known as Cerberus Fossae, around 1,000 miles east of Elysium Planitia.

The finding is significant as the quakes are thought to be created by the cooling and subsequent shrinking of the planet, alongside general tectonic plate shifting like we have on Earth.

The Martian seismic activity recorded by the lander’s seismometer - a ground-motion detection sensor - was found to be greater than that of the Moon, but less than that of Earth.

“As the planet cools, it contracts and then the brittle outer layers have to fracture in order to sort of maintain themselves on the surface. That’s kind of the long-term source of stresses,” said planetary geophysicist and mission principal investigator Bruce Banerdt.

The team believes that understanding more about the seismic activity of planets other than Earth could reveal clues about how the Solar System formed.

Dr Domenico Giardini, of ETH Zurich in Switzerland and lead author on one of the studies, added: “Marsquakes have characteristics already observed on the Moon during the Apollo era, with a long signal duration (10 to 20 minutes) due to the scattering properties of the Martian crust.”

The researchers devised a magnitude scale tailored to Mars, but similar to the one used for earthquakes. The strongest of the quakes were a little less than magnitude 4, meaning they would be felt on the surface perhaps dozens of miles from the epicenter but probably would not do much damage.

Evidence of dust devils, which are whirls of Martian soil whipped up by the wind that spin like a tornado at nearly 60mph, were observed a month after InSight touched down on Mars.

The £633 million Nasa mission is expected to continue for another year.

In June, Nasa’s Curiosity rover discovered the largest amount of methane measured during its near seven-year mission, a potential sign of life after recent doubts about how much methane the planet really produces.

Frequency adjustment and protection of a wind turbine due to wind gust is a salient aspect of the grid-tied wind farm. Both of them require conserving system stability. This paper presents an investigation of the converter based frequency adjusting method and wind turbine protection. A grid-tied wind power system model using the Doubly Fed Induction Generator in MATLAB is used. To regulate the active power output, synchronization between wind velocity and wind turbine speed is adjusted. Thus, wind farm operated at grid frequency and maximize turbine output. The control strategy of the converter based frequency synchronization of a grid-tied wind farm also includes protection subsystem. The protection system executed by receiving information from the logical block implemented in the wind farm model. It provides wind turbine protection by terminating wind turbine from a grid in abnormal wind conditions. The Simulation result validates the results and control methods.

Continues expanding of wind power harnessing demands an effective control system to improve quality power delivered from wind turbine to grid. A stable power system fully depends on the synchronization that means matching of frequency between the source of power generation and existing power grid. The prime objective of a wind farm controller is to ensure effective operation of the wind farm in any wind speed condition. Frequency deviation between the wind system and grid can challenge the well-built operation of a power system and can imbalance the synchronization between wind farm and grid. The strategy of frequency adjustment is developing time to time which starts from using droop controller based Induction generator to converter based Double-fed Induction generator. This paper summarizes an analytical study on various frequency adjustment mechanisms for a grid-connected wind farm.

২০৪১ সালের মধ্যে বাংলাদেশের মানুষের মাথাপিছু আয় বেড়ে দাঁড়াবে ১২ হাজার ৫০০ মার্কিন ডলারের বেশি। ওই সময়ে হতদরিদ্রের হার কমে শূন্যের ঘরে নেমে আসবে। আর মোট দেশজ উৎপাদনে (জিডিপি) প্রবৃদ্ধি হবে ৯ দশমিক ৯ শতাংশ।

রূপকল্প ২০৪১ বাস্তবায়নে ‘বাংলাদেশের দ্বিতীয় প্রেক্ষিত পরিকল্পনা ২০২১-২০৪১’ শীর্ষক প্রতিবেদনে এই লক্ষ্য ঠিক করা হয়েছে। পরিকল্পনা কমিশনের সাধারণ অর্থনীতি বিভাগের (জিইডি) তৈরি এ প্রতিবেদন অনুমোদনের জন্য আজ মঙ্গলবার জাতীয় অর্থনৈতিক পরিষদের (এনইসি) সভায় তোলার কথা। এতে সভাপতিত্ব করবেন প্রধানমন্ত্রী শেখ হাসিনা।

জিইডি বলছে, নতুন প্রেক্ষিত পরিকল্পনাটি চারটি প্রাতিষ্ঠানিক স্তম্ভের ওপর নির্ভরশীল। সেগুলো হচ্ছে সুশাসন, গণতন্ত্রায়ণ, বিকেন্দ্রীকরণ ও সক্ষমতা বৃদ্ধি।

জানতে চাইলে জিইডির সদস্য শামসুল আলম প্রথম আলোকে বলেন, ‘এটি হলো মোটাদাগে বাংলাদেশের উন্নয়নের পথচিহ্ন। কীভাবে বাস্তবায়ন করা হবে, সেই কর্মপরিকল্পনা নেওয়া হবে পঞ্চবার্ষিক পরিকল্পনার মাধ্যমে। প্রেক্ষিত পরিকল্পনা বাস্তবায়ন করতে চারটি পঞ্চবার্ষিক পরিকল্পনা করতে হবে।’ তিনি জানান, প্রেক্ষিত পরিকল্পনা বাস্তবায়নে কত টাকা লাগবে, তা পঞ্চবার্ষিক পরিকল্পনায় ঠিক করা হবে। তবে বিনিয়োগের জন্য বেসরকারি খাতকে প্রাধান্য দেওয়া হয়েছে।

২০৪১ সালে দেশে হতদরিদ্রের হার শূন্যের ঘরে নেমে আসবে। তখন জিডিপি প্রবৃদ্ধি হবে ৯ দশমিক ৯ শতাংশ।

প্রতিবেদনে বলা হয়েছে, বাংলাদেশ ২০৪১ সালের মধ্যে উন্নত দেশে উন্নীত হবে। বর্তমান বাজারমূল্যে তখন মাথাপিছু আয় দাঁড়াবে ১২ হাজার ৫০০ ডলারের বেশি, যা বর্তমানে ১ হাজার ৯০৯ ডলার। এ ছাড়া ২০৩০ সালের মধ্যে হতদরিদ্র নির্মূল হবে (৩ শতাংশে নামলে নির্মূল বলা হয়)। আর ২০৪১ সালে হতদরিদ্রের হার কমে দশমিক ৬৮ শতাংশ হবে, যা বর্তমানে ৯ দশমিক ৩৮ শতাংশ। ২০৪১ সালে জিডিপি প্রবৃদ্ধি হবে ৯ দশমিক ৯ শতাংশ। এই হার বর্তমানে ৮ দশমিক ১৯ শতাংশ।

বর্তমানে মোট বিনিয়োগের পরিমাণ জিডিপির ৩২ দশমিক ৭৬ শতাংশ, যা ২০৩০ সালে বেড়ে দাঁড়াবে জিডিপির ৪০ দশমিক ৬০ শতাংশ। আর ২০৪১ সালে মোট বিনিয়োগ দাঁড়াবে ৪৬ দশমিক ৮৮ শতাংশ।

অন্যদিকে বর্তমানে মোট রাজস্বের পরিমাণ জিডিপির ১০ দশমিক ৪৭ শতাংশ। সেটি ২০৩০ সালে বেড়ে ১৯ দশমিক ০৬ শতাংশ হবে। আর ২০৪১ সালে রাজস্ব আহরণের পরিমাণ দাঁড়াবে জিডিপির ২৪ দশমিক ১৫ শতাংশ।

প্রেক্ষিত পরিকল্পনা অনুযায়ী ২০৪১ সালে দেশের জনসংখ্যা বেড়ে ২১ কোটি হবে। তখন মানুষের গড় আয়ু ৮০ বছরে উন্নীত করার লক্ষ্য নেওয়া হয়েছে। জনসংখ্যা বৃদ্ধির হার ১ শতাংশে নামিয়ে আনা হবে। শিশুমৃত্যুর হার (১ হাজার জীবিত জন্মে) ২৪ শতাংশ থেকে ৪ শতাংশে নামিয়ে আনা হবে।

প্রতিবেদনে বলা হয়েছে, আগামী দিনে দরিদ্র জনগোষ্ঠীকে মানবসম্পদে পরিণত করতে পর্যাপ্ত বিনিয়োগ করাই হবে চ্যালেঞ্জ। এ জন্য অতিরিক্ত তহবিলের প্রয়োজন হবে, যা দরিদ্র মানুষের কাজ পাওয়ার ক্ষেত্রে বৈষম্য দূর করাসহ খাদ্য, বস্ত্র, বাসস্থান, স্বাস্থ্য ও মানসম্মত শিক্ষার মতো সামাজিক সুরক্ষাবেষ্টনী নিশ্চিত করবে। দারিদ্র্য নিরসনে মানব উন্নয়নের জন্য সাক্ষরতার হার শতভাগ, ১২ বছর পর্যন্ত অবৈতনিক শিক্ষা এবং সাশ্রয়ী মূল্য চিকিৎসাসুবিধা ও স্বাস্থ্যবিমা স্কিম নিশ্চিত করতে কর্মসূচি নেওয়া হবে।

Analysis and detection of human voice at workplace such as telecommunications, military scenarios, medical scenarios, and law enforcement is important in assessing the ability of the worker and assigning tasks accordingly. This paper represents the results from a preliminary study to recognize the speech from human voice using mel-frequency cepstrum coefficients (MFCC) features. The 16 mel-scale warped cepstral coefficients were used independently for reorganization of speech from two Bangla commands of our native language. Cepstral coefficients for the utterance of `BATI JALAO' (i.e., TURN ON LIGHT) and `PAKHA BONDHO KORO' (i.e., TURN OFF FAN) from a particular speaker under preliminary investigation were used as features in a neural network. Network is trained using the MFCC features of two speakers in such a way that it can recognize only one particular person along with his command and terminate the program for other. Result of matching features in a neural network demonstrates that MFCC features work significantly to recognize speech.

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