What is BiCMOS Technology?

CMOS and Bipolar are two of the pioneering technologies of the electronics field. Components fabricated with the CMOS technology dissipate lower power, have smaller noise margins, and are physically smaller. On the other hand, components fabricated with the bipolar technology operate at higher speeds, switch faster, and offer good noise performance. By combining the two, scientists have created the BiCMOS technology that offers a combination of advantages from both processes. For instance, BiCMOS offers higher speeds compared to that of CMOS, and lower power dissipation compared to that of bipolar. However, the penalty comes in the form of added process complexity and it adds to the cost. Both CMOS and bipolar issues need optimization of impurities, and this increase in process complexity results in higher costs compared to that of conventional CMOS.

Scientists have worked out the optimum approach to fabricate high performance BiCMOS devices. They have found it best to start with a baseline CMOS process and add the bipolar process steps. This produces an optimum BiCMOS process flow, emphasizes reliability and process simplicity, while maintaining compatibility with the CMOS technology.

There are several advantages of the BiCMOS technology. The higher impedance of the CMOS circuitry facilitates the analog amplifier input design, while bipolar transistors define the rest. BiCMOS can stand wide temperature variations and process variations, which make this technology more economical. BiCMOS devices can source and sink much higher load currents because of the MOS part, while it handles higher speeds because of the bipolar part. BiCMOS can drive high capacitance loads with lower cycle times. As the source and drain can be interchanged, BiCMOS demonstrates bidirectional capabilities, which makes it suitable for IO intensive applications.

BiCMOS technology has its drawbacks as well. The fabrication complexity is higher because both CMOS and bipolar technologies are involved. This increases the cost of fabrication also. However, as BiCMOS devices have higher density, the amount of lithography required is lower.

BiCMOS technology is versatile for several applications. Its higher speed makes it suitable for AND functions of high density. It easily replaces devices formed with earlier technologies such as CMOS, ECL, and bipolar, for instance, in some cases BiCMOS has higher speed performance compared to that from bipolar. A single chip with the BiCMOS technology can span the analog-digital boundary. Their high impedance input makes BiCMOS a very good candidate for applications such as sample and hold, adders, mixers, ADCs, DACs.

STMicroelectronics integrates RF, analog, and digital parts on a single chip. Their BiCMOS SiGe technology reduces the number of external components drastically, while optimizing the power consumed by the chip. The advantages of the integration are significant as earlier, only more expensive technologies were able to achieve this level of performance.

As ST explains, the Heterojunction Bipolar Transistor (HBT) of BiCMOS has a much higher cut-off frequency compared to bulk CMOS. To attain such frequencies, the bulk CMOS designs need to use far smaller process nodes. This forces design compromises leading to overall lower performances and higher costs. Therefore, the BiCMOS technology offers a better cost profile compared to other alternatives.

Window Blinds Offer Shade and Electricity

Everyone is looking for clean energy, because awareness is growing of the problems the use of fossil fuels is creating. Although alternate forms of energy from wind and waves is viable now, solar energy is more accessible to all, since it needs only a solar cell placed in the sun to start generating energy. SolarGaps from Ukraine offers a new type of window blinds that do double duty. You can control the smart shades by an app on your smartphone, and while they screen your house from the fierce rays of the sun, they capture and store the energy falling on them. The smart shades use an in-built solar tracking technology that can reduce the amount of electricity you consume by an impressive 70%.

At SolarGaps, innovator Yevgen Erik and his team aim to change the way we consume energy in our homes. The designers claim their window blinds can generate power up to 100 Watts per ten square feet of window space. According to SolarGaps, this is enough energy to light up 30 LED bulbs or charge three MacBook simultaneously. It is very easy to setup on the window, since SolarGaps offers complete instructions to get everything up conveniently.

The smart shades begin harvesting energy from the sun almost as soon as they have been setup, and the user can power up a range of household gadgets. To catch the optimum amount of sunlight, SolarGaps offers an app for smartphones that has the option of adjusting the orientation of the window blinds. Along with controlling the orientation, the app also shows the amount of energy produced by the system. Therefore, the user only has to adjust the orientation until it produces the maximum energy.

If you have a battery storage system in your home, connect it to the smart shades to store the energy it produces. This can power up your emergency power supply when you need it, say at night, or when clouds cover the sun in the daytime. Therefore, with the smart window blinds from SolarGaps, you can generate your own electricity and save on your electricity bills. The smartphone app allows the user to monitor and adjust the smart blinds from anywhere in the world.

SolarGaps has fashioned their window blinds from Aluminum, with each blind covered with a set of high-efficiency solar cells from SunPower, a company based in California. The company claims their solar cells can last up to 25 years, and these window blinds are capable of operating in widely varying climates. For instance, the window blinds operate comfortably from -40°C to +80°C.

The company is making solar window blinds in different sizes for accommodating then on all types of windows. The smallest variety, XS, measures 32 inches x 36 inches or 810 mm x 910 mm and costs about $390. A wide range of sizes is available, including small, medium, large, extra-large, and extra-extra-large as well.

SolarGaps is currently targeting homeowners, and their solar window blinds is making green energy easily available to everybody.

How Good are Cobots at Welding?

The manufacturing industry has been using robots widely for several years as a replacement for the human laborer. Recent advances in this field are the Cobots or collaborative robots. They are called collaborative as their design makes them work alongside an individual as a part of a team rather than replacing the humans.

Cobots are good at operations and activities that cannot be fully automated. However, the process speed does not improve for activities such as workers ferrying parts backwards and forwards between themselves on the assembly line with the robots locked away in cages.

Manufacturers such as Ford are already on the cobot bandwagon, and the new robots could transform the way the industry works. The Ford factory has collaborative robots installing shock absorbers on vehicles on the production line along with humans. The cobots work with accuracy and precision, boosting the human productivity, while saving them valuable time and money.

At present, the industry uses four main types of cobots. They are the Safety Monitored Stop, Speed and Separation Monitoring, Hand Guiding, and Power and Force Limiting.

The Safety Monitored Stop is a collaborative feature used when the cobot works on its own, but sometimes needing assistance from an operator. For instance, in an automated assembly process, the worker may need to step in and perform an operation on a part that the cobot is holding. As soon as the cobot senses the presence of the human within its workspace, it will cease all motion until the worker leaves the predetermined safety zone. The cobot resumes its activities only after receiving a signal from its operator.

Speed and Separation Monitoring is similar to the Safety Monitored Stop, with the cobot operating in a predetermined safety zone. However, this cobot’s reaction to humans is different. The Cobot will not automatically stop because of the human presence, but will slow down until its vision detection system informs it of the location of the person or object. The Cobot stops only if the person is within a predetermined area, and waits for the proximity to increase before resuming its operations. This cobot is useful in areas with several workers are present, at it requires far fewer human interventions.

Although a Hand Guiding cobot works just as a regular industrial robot does, it has additional pressure sensors on its arm device. The operator can therefore teach the cobot to hold an object hard enough and to move it fast enough without damaging the object, while securely working with it. Production lines that handle delicate components find Hand Guide cobots very useful for careful assembly.

Power and Force Limiting cobots are among the most worker-friendly machines. They can sense unnatural forces in their path, such as humans or similar objects. Their joints are programmed to stop all movement at such encounters, and even reverse the movement.

As many skilled workers retire, and replacements are rare, the American Welding Society is working with Universal Robots, to produce a new attachment to their UR+ line of cobots with welding capabilities. The robot moves along the start and stop path of the desired weld, and welds only the specified stitch areas.

Keeping Your Raspberry Pi Cool

Any PC motherboard is practically useless until you add some cooling and other accessories. This is because modern processors require cooling as they generate heat when operating. This is regardless of whether the processor is an x86, x64, an ARM based system such as the Raspberry Pi (RBPi), any other Linux or Android chipset, MIPs, or belonging to any other design.

The general explanation is the internal circuitry within the processor is microscopic and does not have the adequate surface area to dissipate the heat it generates while operating. Therefore, heat buildup within the IC can be detrimental, affecting its performance, unless the heat is removed. Designers usually build-in some safeguards against temperature rise to make the processor fail-safe. For instance, the PC has this feature as a part of the BIOS, and combined with the power management software at the OS level, keeps the CPU from being fried.

The RBPi single board computers run on an ARM chipset that follows the Reduced Instruction Set Computing or RISC architecture. Unlike the x86/x64 chipsets that follow the Complex Instruction Set Computing or CISC architecture, ARM chipsets do not need BIOS, but instead rely on a text file to feed it BIOS-like instructions when booting up. Notwithstanding the differences, the RBPis are as much a computer as those based on the Intel or Apple chipsets are, and prone to much the same issues of heat generation.

A research team at Microsoft, working on AI models and methods of shrinking image recognition to run on RBPi SBCs, has found a simple but effective way to reduce the heat the RBPi CPU generates while running their processor intensive workloads.

An internal protection on the RBPi3 disables it from overclocking when the ARM CPU reaches a core temperature of 85 degrees Celsius. In severe cases of overheating, the internal protection may also shut down the CPU. However, such interruptions are a real problem for any complex machine learning model programs the tiny device is running.

It is usual for a user to place a small heat sink on the RBPi3 CPU to help it to dissipate the heat and keep it cool. However, as the team at Microsoft discovered, this cooling is not adequate for some intensive workloads. According to the principal researcher Ofer Dekel at Microsoft, the cooling kits offered for the RBPi include heatsinks for the CPU and other components, but this is not adequate. Infrared images of the board point out that more work is necessary in cooling the processor.

Adafruit already supplies a miniature fan running on 5 VDC that users can mount on top of the RBPi CPU. However, for those mounting the RBPi on a 7-inch touchscreen display, this tiny fan can be a hindrance.

Therefore, the Microsoft team designed and 3-D printed a different fan mount. The design allows them to mount the Adafruit cooling fan directly on to standoffs available on the 7-inch display. With this arrangement, although the fan is pointing directly at the CPU, it is positioned at an angle beside the CUP rather than sitting directly on top.

What is an i-Robot?

The level of CO2 in our atmosphere is increasing at alarming levels, affecting all life on Earth either directly or indirectly. For instance, it is related to global warming risks, reducing the quantity of ice in the polar regions, which in turn changes the level of seas all around as the ice melts. This has significant consequences on several human activities such as fishing. It also affects the submarine environment adversely, together with the associated biological sphere. For long, scientists have been monitoring the marine environment and studying the status of the seas.

However, the harshness of the marine environment and/or the remoteness of the location preclude many explorations under the sear by vehicles driven by the mother ship. Scientists are of the view robots could effectively contribute to such challenging explorations. This view has led to the development of Autonomous Underwater Vehicles or AUVs.

One such AUV is the Semi-Autonomous Underwater Vehicle for Intervention Mission or SAUVIM, and is expected to address challenging tasks as above. The specialty of SAUVIM is its capability of autonomous manipulation underwater. As it has no human occupants and no physical links with its controller, SAUVIM can venture into dangerous regions such as classified areas, or retrieve hazardous objects from deep within the oceans.

This milestone is a technological challenge, as it gives the robotic system the capability to perform intervention tasks such as physical contact with unstructured environment but without a human supervisor constantly guiding it.

SAUVIM, being a semi-autonomous vehicle, integrates electronic circuitry capable of withstanding the enormous pressure deep ocean waters generate. In general, it can operate in the harsh environmental conditions—low temperatures of the deep oceans—in a reliable and safe manner. Ensuring the effectiveness of such robots requires a high level of design and accurate choice of components.

As SAUVIM operates semi-autonomously, it needs huge energy autonomy. For this, Steatite, Worcestershire, UK, has introduced a new solution in the form of long-life batteries, ones capable of operating in submarine environment. These Lithium-Sulfur (Li-S) battery packs, a result of the first phase of a 24-month project, improves the endurance and speed of autonomous underwater vehicles when deep diving.

Primary advantages that Li-S batteries offer are enhanced energy storage capability to provide improvements in operational duration, despite being constructed from low-cost building materials.

The National Oceanography Center in Southampton, UK, completed the first phase of the Li-S battery project, after repeatedly testing the cells at pressure and temperatures prevailing in undersea depths of 6 Kms. According to the tests, Li-S cells can deliver performances similar to those at ambient conditions, while their effective Neutral Buoyancy Energy Density or NBED is almost double that offered by Li-ion cells used as reference. Life tests, performed on a number of Li-S cells demonstrate they can reach over 60 cycles with slow discharge, and 80 cycles with fast discharges.

The energy within an AUV is limited, which also limits its endurance. Therefore, to conserve the available energy, speeds of AUV are usually kept low at 2-4 knots. Therefore, to enhance or expand this operational envelope, it is necessary to increase the energy available within the vehicle, and the Li-S batteries do just that to increase the vehicles range and speed.

Where are AREE Rovers Going?

NASA is planning new types of rover explorers for observing extreme environments, such as the surface of Venus. They plan to build simple yet robust vehicles. AREE is their acronym for Automaton Rovers for Extreme Environments.

NASA’s Curiosity Rover on Mars has been roving and exploring the planet’s surface for the last five years. Among rovers, Curiosity is at the top position. It uses special systems for rejecting heat, X-band receiver and transmitter for communicating directly with Earth, an Electra-Lite radio (UHF) for communicating with the Mars Orbiters, instruments for mineralogy and chemistry, instruments for simple analysis, and much more.

According to Jason Derleth, NASA prefers to do the absolute maximum when sending a rover into space, such as making sure the rover can contribute as much to science as is possible. Jason is the head of NASA’s Innovative Advanced Concepts Program (NIAC).

However, Venus is vastly different from Mars. Although very similar to Earth in its size, mass, and density, Venus has an incredibly thick atmosphere—a mix of carbon dioxide, nitrogen, and sulfur dioxide. This raises the temperature on the surface of Venus to over 450°C, which is hot enough to melt lead or high enough for paper to spontaneously combust. The atmospheric pressure at the surface is 92 bar or 1,334 psi, with a density enough to crush a submarine.

In the past, some robots have succeeded in reaching Venus. These were the Soviet Union’s Venera and Vega landers, and the Pioneer probe from NASA. Although they were successful in reaching the planet’s surface, they could function only between 23 and 127 minutes before the oppressive environment snuffed out their electronics.

With the AREE rovers, NASA is trying a new concept, inspired by mechanical clockwork computers and tanks used in World War I. A NASA program, NIAC, is funding the AREE rovers. It is offering small grants for developing early stage technology, which allows engineers to work on long-term ideas for properly developing the technology.

For instance, the most recent funding from NASA related to the development of a rough prototype of the rover concept, which will take about three years. Jonathan Sauder was the first to propose the concept. In 2015, Sauder had observed mechanical computers using levers and gears for performing calculations rather than rely on electronics.

The AREE rovers would be using these analog techniques mainly to survive the harsh environments on Venus. They would traverse the planet’s surface moving on tank treads that overcame the rough terrain. As wind gusts on Venus are high, they would turn wind turbines located at the center of the rover to supply it with the necessary power. The robot would capture the power from the turbines inside springs before distributing it to the other subsystems of the robot. Think of a windup watch, the idea is very similar.

Curiosity has several cameras to measure, map, and guide it over the Marian terrain. However, the electronic functionality of the AREE rovers will be purposely kept simple. Although AREE’s design will make it robust enough to withstand unexpected bumps and drops, it will integrate a simple optical reflector to transmit data to the orbiting satellite.

Butterfly IQ – Smartphone Connected Ultrasound Scanner

Traditional ultrasound scanners are rather expensive, and rarely do people own one to use at home. However, that may be about to change, as Butterfly IQ has now obtained FDA clearance for a portable ultrasound scanner that anyone can use by connecting to their smartphones.

Connecticut-based Butterfly IQ has made an innovative ultrasound scanner that uses a semiconductor chip for generating the ultrasonic signals, rather than the piezoelectric crystal transducers that traditional ultrasound machines use. The semiconductor chip based transducer is much easier to manufacture than the piezoelectric ones are.

Using the semiconductor chip makes the device much less expensive as compared to existing ultrasonic scanners. The cost of ownership comes down further as the device can operate with a smartphone and other smartphone connected devices such as the Philips Lumify device.

According to Dr. Jonathan Rothberg, founder and chairperson of Butterfly Network, this ultrasound-on-a-chip technology opens up a low-cost window for peering into the human body, allowing anyone to access high quality diagnostic imaging. With more than two-third of the population of the world without access to proper medical imaging, this effort by Butterfly is a great beginning.

FDA has cleared the device for 13 different clinical use cases. These include pediatric, urological, gynecological, cardiac, abdominal, and fetal use cases. The scanner transfers the captured imagery directly to the user’s smartphone via a chord, and the smartphone stores the images into a HIPAA-compliant cloud.

As reported by the MIT Tech Review, the chief medical officer of Butterfly Network, Dr. John Martin, was able to detect cancerous growth in his body while testing the scanner. This is an example of the potential of the low-cost ultrasound scanner.

According to Martin, the easy-to-use, powerful, healthcare providers will be able to afford the whole-body medical imaging system for less than $2,000, and it will fit in their pockets. As the price barrier comes down, Martin expects the Butterfly device to replace the stethoscope ultimately in the daily practice of medicine. The impact this technology will provide as a low-cost diagnostic system, can be gaged from the help it will offer to hundreds of thousands of women who die in childbirth, and the millions of children who die of pneumonia each year.

After perfecting the scanner, Butterfly has plans to augment its hardware capabilities with software for artificial intelligence. This will help clinicians interpret the images that the device picks up. The company expects the products with many new features to be ready for the market by 2018. At present, the device works only with iPhones.

According to the President of Butterfly IQ, Gioel Molinari, ultrasound imaging makes a perfect combination with deep learning. With more physicians using the devices in the field, the neural network models keep improving. As physicians use the Butterfly scanner regularly, they will be able to interpret the results better. This will help improve the acquiring and interpretation of the image by the artificial intelligence, which in turn, will help less skilled users to extract life-saving insight from the images captured by the Butterfly IQ ultrasound scanner on the field.

Blinkt! is Compatible with the Raspberry Pi

If you are keen on learning how to control RGB LEDs with the Raspberry Pi (RBPi) single board computer, Blinkt! provides a simple way to interface. Blinkt! is a strip of eight superbright RGB LED lights that you can connect to the RBPi without wires, so it is an easy way to start. Blinkt! Has a female connector that matches the male GPIO connector on the RBPi, and that allows the tiny LED board to sit atop the RBPi.

The RBPi can individually control each of the eight APA102 RGB LEDs on the Blinkt! board individually, so you can consider them as matrix of 1×8 pixels. The footprint of the board is tiny enough to allow it sit directly on top of the RBPi and the pair fits inside most of the Pi cases. Although the RBPi controls the eight LEDs with PWM, it does not interfere with the SBC’s PWM audio. Blinkt! comes fully assembled and is compatible with RBPi models 3, 2, B+, A+, Z, and ZW. Pimoroni, the manufacturers of Blinkt!, also provide a Python library for the users.

Combining Python programming and Blinkt! with the RBPi is a great way of understanding how RGB LEDs work and how a computer program controls their operation.

If you are using the RBPi3 for this project, it will already have the male GPIO on the board. However, the RBPiZ and RBPiZW may not have the connector, which means you may need to solder the connector to the board. You need to be careful when plugging the Blinkt! board onto the RBPi taking care to orient it in the right way. The Blinkt! board has rounded corners on one of its side, and this side should face the outside of the RBPi. Once you align the boards properly, push the Blinkt! board in and it should fit snugly on the RBPi.

To make the RBPi control the LEDs on the Blinkt!, it will need to have the right code. The best way to begin is to update the Operating System of the RBPi to the latest Raspbian. Once you have done this, and the RBPi is running, connect it up to the Internet and open the terminal on the RBPi screen.

Typing the code “curl https://get.pimoroni.com/blinkt | bash” without the quotes, should allow the RBPi to download the necessary Python libraries from the Pimoroni website. Now you can use the Python 3 IDLE code editor to use the library to write the Python program and control the LEDs.

While writing the Python program, you will need to begin by importing the Blinkt! library you had downloaded in the first step. Each LED is termed as a pixel so the parameter “set_pixel” allows you to address a specific LED, while “set_brightness” allows setting its brightness. The command “show” turns on the specific LED, and “clear” turns it off.

Even though the LEDs are numbered as 1 to 8 on the board, the program addresses them as 0 through 7. Therefore, the program can pick a light and tell it the color it needs to be, its brightness, and whether it should turn it on or off.

Cloud Storage and Alternatives

Ordinarily, every computer has some local memory storage capacity. Apart from the Random Access Memory or RAM, computers have either a magnetic hard disk drive (HDD) or a solid-state disk (SSD) to store programs and data even when power is shut off—RAM cannot hold information without power. The disk drive primarily stores the Operating System that runs the computer, other application programs, and the data these programs generate. Typically, such memory is limited and tied to a specific computer, meaning other computers cannot share it.

A user has two choices for adding more memory to a computer—he/she can either buy a bigger drive or add to the existing one, or he can use cloud storage. Various service providers offer remote memory storage, and the user has to pay a nominal rental amount for using a specific amount of cloud memory.

There are several advantages of using such remote memory. Most cloud storage services offer desktop folders where users can drag and drop files from their local storage to the cloud and vice versa. As accessing the cloud services requires Internet connection, the user can avail the cloud facilities from anywhere, while sharing it between several computers and users.

The user can use the cloud service as a back up for storing a second copy of their important information. In the event an emergency strikes and the user loses all or part of their data on their computer, accessing the cloud storage through the Internet can help to restore the stored information on the cloud. Therefore, cloud storage can act as a disaster recovery mechanism.

Compared to local memory storage, cloud services are much cheaper. Therefore, users can reduce their annual operating costs by using cloud services. Additionally, the user saves on power expenses, as cloud storage does not require the user to supply power that local memory storage would need.

However, cloud storage has its disadvantages. Dragging and dropping files to and from the cloud storage takes finite time on the Internet. This is because cloud storage services usually limit the bandwidth the user can avail for a specific rental charge. Power interruptions and or bad Internet connection during the transfer process can lead to corruption of data. Moreover, the user cannot access his/her data on the cloud storage unless there is an Internet connection available.

Storing data remotely also brings up the concerns of safety and privacy. As the remote memory is likely to be shared by other organizations, there is a possibility of data comingling.

Therefore, people prefer using private cloud services, which are more expensive, rather than using cheaper public cloud services. Private cloud services may also offer alternative payment plans, and these may be more convenient for users. Usually, the private cloud services have better software for running their services, and offer users greater confidence.

Another option private cloud services often offer is of encrypting the stored data. That means only the actual user can make use of their data, and others, even if they can access it, will see only garbage.

What is a Wireless Router?

Most of the electronic gadgets we use today are wireless. When they have to connect to the Internet, they do so through a device called a router, which may be a wired or a wireless one. Although wired routers were very common a few years back, wireless routers have overtaken them.

Routers, as their name suggests, direct a stream of data from one point to another or to multiple points. Usually, the source of data is the transmitting tower belonging to the broadband dealer. The connection from the tower to the router may be through a cable, a wire, or wireless. To redirect the traffic, the router may have a network of multiple Ethernet ports to which users may connect their PCs, or, as in the latest versions, it may transmit the data wirelessly. The only wire a truly wireless router will probably have is a cable to charge its internal battery.

Technically speaking, the wireless router is actually a two-way radio, receiving the signals from the tower and retransmitting them for other devices to receive. A SIM card inside the router identifies the device to the broadband company, helping it to keep track of the routers statistics. Modern wireless routers follow international wireless communication standards—the 802.11n being the latest, although there are several of the type 802.11b/g/n, meaning they conform to the earlier standards as well. Another differentiation between various routers is their operating speed, and the band on which they operate.

The international wireless communication standards define the speed at which routers operate. For instance, wireless routers of the type 802.11b are the slowest, with speeds reaching up to 11 Mbps. While those with the g suffix can deliver a maximum speed of 54 Mbps, those based on the 802.11n standard are the fastest, reaching up to 300 Mbps. However, a router can deliver data only as fast as the Internet connection allows. Therefore, even if it has a rating of n or 300 Mbps, it will perform at speeds of 100 Mbps at the most. Nonetheless, a fast wireless router can increase the speed of your network, and this allows PCs to interact faster, making them more productive.

International standards allow wireless communication on two bands—2.4 GHz and 5.0 GHz. Most wireless routers based on the 802.11b, g, and n standards use the 2.4 GHz band. These are the single band routers. However, the 802.11n standard allows wireless devices to operate on the 2.4 GHz or the 5.0 GHz band also. These are the dual-band routers, which can transmit in either of the two bands via a selection switch, or in some devices, they can operate in both frequencies at the same time.

A newer standard, 802.11a, allows wireless networking on the 5.0 GHz band, while also transmitting on the 2.4 GHz band used by the 802.11b, g, and n standards. These are also dual band wireless routers with two different types of radios that support connections on both 2.4 GHz and 5.0 GHz bands. The 5.0 GHz band offers better performance, lower interference, and more coverage.