Optical Illusions


The most remarkable thing in a remarkable universe is so commonplace that it is accepted without wonder or understanding. This is the appearance of reality and solidity that surrounds us when our eyes are open, which we call simplyvision. Intellectual effort is required to realize that this seeming reality is within us, distinct for each individual, but so concordant with reality and with each other, and so stable, that it is accepted without question. The explanation for this wonderful aspect of consciousness is completely unknown.



The information that allows the mind to create and maintain this appearance is collected entirely by the visual system. When the eyes are closed, the appearance vanishes. At least, it does for me. Some people may be able to create realistic pictures with their mind’s eye, but I cannot. I can still imagine my environment more or less accurately, but the vivid picture is gone.

The ability to make an accurate visual model of the external world is learned, not innate. The necessary materials are there at birth, of course, but they must be trained, or programmed, before the skill is perfected.

KC Yee

This seems to be done in the first instance by comparing the chaotic impressions of light with the solid evidence of touch, which gives the perception depth and form. The visual sense ever after shows subtle indications of its origin in touch, though it becomes completely independent of touch after perfection. The ability to acquire this skill vanishes early in mental development. A person totally blind from birth whose vision may become normal at a later age can never make sense of the visual information and arrange it in a consistent manner.

The Chain of Perception

There are three links in the chain of perception. The first is external and physical: the propagation of electromagnetic waves from the object to the eye. The second is the physical visual apparatus, from eye to brain, consisting of nervous tissue, although some important preliminary processing takes place. The third, and most complex, is the interpretation of the visual stimulus and the creation of the internal model of the world that is used by the consciousness.

In the third step, the visual stimulus received from outside is combined with information from the memory to create the picture. This is the most important part of vision, and how it is done is unknown. All the really interesting parts of vision occur here. The physical visual system from eye to brain has been (KC) studied in exquisite detail, its parts examined and described, and even the nerve impulses observed and measured, but all this gives no satisfying explanation of vision. It has been established, however, that important preliminary processing takes place here, including the differencing and the coding of stimuli. Coding is necessary to reduce the flood of information to a manageable amount. The visual system has a bandwidth problem, indeed.

The world picture must be constructed from incomplete information, in fact inferred from clues. The three-dimensional world is sensed by the two- dimensional retina, emphasizing the central role of depth clues. The picture depends on the unconscious recognition of objects, so that the remembered properties of objects can be transferred to those they seem to be on the basis of visual hints. Recognition is what gives vision its reality, showing the central role of mind.

Illusion and Hallucination

A picture so assembled on the basis of partial information must be expected to occasionally be in error. The mind will always try to match stimulus and memory to create a picture. It will make what yee seems to be the most likely choice, and present that to the consciousness. An illusion occurs when the choice is incorrect. If a picture is created solely from memory, without visual stimulus (or with only a minimal visual stimulus) the result is hallucination, with which we shall not be concerned here, since it is a disorder of perception, not a normal or intended part of it. Things that are not there can also appear in illusion, it must be emphasized, but here it is normal.

An illusion can arise in any of the three links of visual perception. The mirage is an example of an external illusion, created in the first, physical link of light rays. It is visually interpreted as an actual scene, though we consciously recognize it as an illusion, and understand its cause. When we stare at a brightly kc illuminated red disk for a time, then transfer our attention to a white paper, we see a green disk as a result of what is called rather inaccurately fatigue. The green disk is an illusion created in the second partly physical, partly mental link. When the full moon is seen at the horizon, it seems much larger than when riding high in the sky, though physically it subtends exactly the same angle at the eye. This familiar illusion occurs in the third, mental link of vision, and a satisfying explanation of it is unknown.

Optical Illusions

Illusions occurring in the third link are those most generally recognized as optical illusions. Their scientific study began with J. Oppel in Jahresberichte des physikalisches Vereins zu Frankfurt, p. 138 (1854). Much work was done later in the century, but tapered off after 1900, although the subject is still actively researched by psychologists. Recent work deals largely with color and motion illusions, not on the static, black- and-white illusions that dominated earlier work. Popular interest in optical illusions has been sustained. The books by M. Luckeish (Visual Illusions, 1920), S. Tolansky (Optical Illusions, 1964), and M. Fineman (The Nature of Visual Illusion, 1981) are evidence of the continuing fascination. Each of these books gives references to further information. All theories of optical illusion in the third yee haw link are mere jejune speculation. Feel free to create your own theories; they will be as valid as those created by many a psychologist!

Sometimes a phenomenon is called an illusion when it really is not, but is simply a true picture of an unexpected observation. An example is the searchlight illusion described by Luckeish. The beam of a bright searchlight is visible because of scattering by dust and fog in its path, so that it seems practically a physical object. When the beam is projected up into the sky, it seems to vanish abruptly while still in full glory. When you look at this apparent end of the beam, you are looking in the direction in which the beam is pointed. If the beam were parallel (as your mind expects) it would, by perspective, narrow to a point. However, a searchlight beam is actually more or less divergent, fooling this expectation. It is only one’s mental interpretation that is an illusion in this case, not the observation. Stars can be pointed out to others by means of a strong laser using this effect. If you yee haw kc view the searchlight beam from a distance, you see it diverge and become attenuated, and perhaps penetrating the layer of dusty air.


Tricking the eye into recognizing one thing while observing another is often very useful to living things. There are three different ways to do this. First, one might mimic something dangerous or nasty-tasting, as does the fly who resembles a wasp, a brightly-colored butterfly, or an armed, uniformed policeman. Another way is to merge with the background, as do moths, stick insects, tabby cats, or wealthy people wearing old clothes in the street. An interesting way to do this is to break up a familiar outline by a contrasting pattern. Warships were painted in bold, zig-zag patterns in the First World War for this purpose. The patterns did indeed break up the outline when you were close enough to see that they were ships, but at large yee haw kc distances aerial perspective (blue haze) smoothed the pattern, revealing again that they were ships. The third way is to look like something else. Cylindrical snakes and lizards are dark on top and light on the bottom, contrary to the normal modelling of a cylinder, so they resemble flat objects containing no meat.

Deliberate Illusions

A picture drawn on a flat background is an attempt to trick the eye into perceiving a three-dimensional scene. This is very effective, since the eye must do something similar in its normal functioning, because the retina is two- dimensional. The skill of perceiving depth and perspective in a painting is learned, not innate. In moving pictures, the mind interprets the succession of static frames as continuous motion, again something it must do in its normal functioning. There must be a temporal element in sensing a changing world, which is revealed by the flicker frequency, the rate above which continuous motion is perceived instead of jumps, of about 20 to 30 Hz. We are very thankful for these illusions (if we realize what they are) and are glad to have them.

Conjurors, three-card monte men, swindlers, mediums, priests, and others interested in influencing people sometimes make effective use of visual (and other) illusion. Stage magicians who are only concerned with entertainment call themselves illusionists to make it clear what they do, and to distinguish themselves from those who ascribe their wonders to spirits or chemicals. Illusionists, and the the other sorts of entrepreneurs, mainly use other kinds of illusions, but optical illusions are not ruled out. These procedures have been perfected through centuries and even millenia of profitable use, and remain evergreen owing to the continuous copious production of fools.

Leg press machine to target different muscles.


Horizontal leg press is probably the simpler variation of the leg press machine because

  • Your head is not declined (position that could cause issues in some people)
  • The effort is lower than the 45 degree leg press



SECONDARY MUSCLES: Hamstrings, Glutes

EQUIPMENT: Seated Leg Press Machine

TYPE: Compound


The purpose of the horizontal leg press machine is to work all your quads muscles, plus glutes and hamstring as secondary muscles.

Horizontal Leg Press

INITIAL POSITION: Seated on the leg press machine, with your back flat on the back support, put your feet on the foot platform, shoulder width. Adjust the platform and seat position so that your quads almost touch your chest in the moment of max relax. In the start position your legs are extended.


K C Yee

MOVEMENT: Slowly bend your knees, apply resistance to the platform that is coming towards you, till the point where your quads almost touch your chest. Then push the platform to the initial position without locking your knees that should be slightly bent.


BREATHING: Inhale while you bend your kCnees and exhale while you push.

The True Sea Bajau People


33 stunning images shortlisted for the Sony World Photography Awards 2017

Tom Jacobi Germany Professional Landscape 2017 Sony World Photography Awards‘Lonely Tree’ by Tom Jacobi is shortlisted in the Professional Landscape category.Sony World Photography Awards

The Sony World Photography Awards is celebrating its 10th anniversary.

To mark the occasion, more than 277,000 photographs have been submitted from 183 countries around the world.

Suffice to say, those that have made Sony’s coveted shortlist are breathtaking and thought-provoking.

Overall winners will be revealed April 20 whereafter they will be exhibited with shortlisted and commended entries at Somerset House in London.

The following shortlisted entries are taken from the Professional and Open competitions — both of which entail 10 categories.

View As: One Page Slides


‘Silent Kingdom’ — Christian Vizl (Mexico), Professional, Natural World

'Silent Kingdom' — Christian Vizl (Mexico), Professional, Natural World

Sony World Photography Awards

‘Moody’ — Ann Ric (Malaysia), Open, Nature

'Moody' — Ann Ric (Malaysia), Open, Nature

Sony World Photography Awards

‘Urban Symmetry’ — Zsolt Hlinka (Hungary), Professional, Architecture

'Urban Symmetry' — Zsolt Hlinka (Hungary), Professional, Architecture

Sony World Photography Awards

‘Mourning Ceremony’ — Emrah Karako (Turkey), Open, Culture

'Mourning Ceremony' — Emrah Karako (Turkey), Open, Culture

Sony World Photography Awards

‘Diamond-Dust’ — Masayasu Sakuma (Japan), Open, Nature

'Diamond-Dust' — Masayasu Sakuma (Japan), Open, Nature

Sony World Photography Awards

‘Far From Gravity’ — Alex Andriesi (Romania), Open, Enhanced

'Far From Gravity' — Alex Andriesi (Romania), Open, Enhanced

Sony World Photography Awards

‘The Human Comedy’ — Vito Leone (Italy), Open, Culture

'The Human Comedy' — Vito Leone (Italy), Open, Culture

Sony World Photography Awards

‘Inhabitants of the Empty’ — Yulia Grigoryants (Armenia), Professional, Daily Life

'Inhabitants of the Empty' — Yulia Grigoryants (Armenia), Professional, Daily Life

Sony World Photography Awards

‘China West’ — Julien Chatelin (France), Professional, Architecture

'China West' — Julien Chatelin (France), Professional, Architecture

Sony World Photography Awards

‘Lonely Tree’ — Tom Jacobi (Germany), Professional, Landscape

'Lonely Tree' — Tom Jacobi (Germany), Professional, Landscape

Sony World Photography Awards

‘The Cub’ — Tim Topple (United Kingdom), Open, Portraits

'The Cub' — Tim Topple (United Kingdom), Open, Portraits

Sony World Photography Awards

‘Buffaloes and Stars’ — Andreas Hemb (Sweden), Open, Wildlife

'Buffaloes and Stars' — Andreas Hemb (Sweden), Open, Wildlife

Sony World Photography Awards

‘Metropolis’ — Tavepong Pratoomwong (Thailand), Open, Street

'Metropolis' — Tavepong Pratoomwong (Thailand), Open, Street

Sony World Photography Awards

‘Lady in Red’ — Placido Faranda (Italy), Open, Travel

'Lady in Red' — Placido Faranda (Italy), Open, Travel

Sony World Photography Awards

‘I Know What Beauty Looks Like’ — Romina Ressia (Argentina), Professional, Portraiture

'I Know What Beauty Looks Like' — Romina Ressia (Argentina), Professional, Portraiture

Sony World Photography Awards

‘Live Chat Studio Industry’ — Lorenzo Maccotta (Italy), Professional, Contemporary Issues

'Live Chat Studio Industry' — Lorenzo Maccotta (Italy), Professional, Contemporary Issues

Sony World Photography Awards

‘Racism in India: The African Portraits’ — Mahesh Shantaram (India), Professional, Portraiture

'Racism in India: The African Portraits' — Mahesh Shantaram (India), Professional, Portraiture

Sony World Photography Awards

‘Food Puns’ — Grant Hegedus (United Kingdom), Professional, Still Life

'Food Puns' — Grant Hegedus (United Kingdom), Professional, Still Life

Sony World Photography Awards

‘I Want to Have an Ordinary Life’ — Li Song (China), Professional, Contemporary Issues

KC Yee

‘Louisiana Flooding’ — Joe Raedle (United States of America), Professional, Current Affairs

'Louisiana Flooding' — Joe Raedle (United States of America), Professional, Current Affairs

Sony World Photography Awards

‘Caught in the Crossfire’ — Ivor Prickett (Ireland), Professional, Current Affairs

'Caught in the Crossfire' — Ivor Prickett (Ireland), Professional, Current Affairs

Sony World Photography Awards

‘Colour and Vision’ — Felicity McCabe (United Kingdom), Professional, Natural World

'Colour and Vision' — Felicity McCabe (United Kingdom), Professional, Natural World

Sony World Photography Awards

‘A Country Doctor and Her Calling’ — Ioana Moldovan (Romania), Professional, Daily Life

'A Country Doctor and Her Calling' — Ioana Moldovan (Romania), Professional, Daily Life

Sony World Photography Awards

‘Los Trumpistas’ — Giulia Piermartiri Edoardo Delille (Italy), Professional, Portraiture

'Los Trumpistas' — Giulia Piermartiri Edoardo Delille (Italy), Professional, Portraiture

Sony World Photography Awards

‘The Little Bullfighters of Mexico’ — Christina Simons (Iceland), Professional, Daily Life

'The Little Bullfighters of Mexico' — Christina Simons (Iceland), Professional, Daily Life

Sony World Photography Awards

‘Palm Trees Routine’ — Andrs Gallardo Albajar (Spain), Open, Still Life

'Palm Trees Routine' — Andrs Gallardo Albajar (Spain), Open, Still Life

Sony World Photography Awards

‘Pumping the Iron in Russia’ — Eduard Korniyenko (Russia), Professional, Sport

Sony World Photography Awards

‘Algo Casual 2’ — Carloman Macidiano Cspedes Riojas (Peru), Open, Portraits

Sony World Photography Awards

‘We are taking no prisoners’ — Tom Jacobi (Germany), Professional, Landscape

'We are taking no prisoners' — Tom Jacobi (Germany), Professional, Landscape

Sony World Photography Awards

‘Standing Rock’ — Amber Bracken (Canada), Professional, Contemporary Issues

'Standing Rock' — Amber Bracken (Canada), Professional, Contemporary Issues

Sony World Photography Awards

‘Pandas Gone Wild’ — Ami Vitale (United States of America), Professional, Natural World

'Pandas Gone Wild' — Ami Vitale (United States of America), Professional, Natural World

Sony World Photography Awards

‘Georgian Baptism’ — Beniamino Pisati (Italy), Open, Culture

'Georgian Baptism' — Beniamino Pisati (Italy), Open, Culture

Sony World Photography Awards

‘Present and Past 1’ — Anisleidy Martnez Fonseca (Cuba), Open, Portraits

Sony World Photography Awards

24 Unusual Beaches You’ve Never Heard Of Before

From When on Earth

Do you think that beaches are blasé tourist destinations with nothing unique or interesting to offer? Well, you’re only partly correct. Many of them are over crowded and boring, but none of the beaches we feature here will disappoint. A singing beach, a glowing beach, a beach with rainbow-colored sand — here are the most offbeat seaside destinations you’ll find on Earth.

1. Glass Beach


Location: Hanapepe, Kauai, Hawaii

What’s so special about it: Though it’s regular rock is basalt, the Glass Beach in Kauai is blanketed with millions of sea glass particles which came from years of discarded glass washed up on shore. Similar beaches include Fort Bragg and Benicia, which are both in California. Source 

2. Green Sand Beach


Location: Papakolea Beach/Mahana Beach, South Point, Ka’u, Hawaii

What’s so special about it: Thanks to the mineral olivine, which comes from the nearby cinder cone, this peculiar beach sparkles a brilliant green. It’s only one of the four beaches in the world with bright green sand, the others being Talofofo Beach, Guam, Punta Cormorant on Floreana Island in the Galapagos Islands, and Hornindalsvatnet, Norway. Source

3. Hot Water Beach


Location: East coast of the Coromandel Peninsula, New Zealand

What’s so special about it: Drive down to this beach armed with a shovel, because the best thing to do here is to dig your very own DIY spa. This geothermal beach can get as hot as 64°C (147°F), its heated water spouting from two nearby underground springs. Check out their website for updates on the water conditions before you drop by. Source

4. Tunnel Beach


Location: Dunedin, New Zealand

What’s so special about it: After trekking across a private farmland, beach-goers must pass this long creepy tunnel to get to the actual beach. On the other side are beautiful sandstone cliffs, rock arches, caves, and other stunning rock formations against the backdrop of the magnificent Pacific Ocean. Source

5. Star Sand Beach


Location: Irimote Island, Japan

What’s so special about it: Visitors of the star sand beaches of Irimote Island and neighboring islands in southern Japan are more often seen crouched over the sand, examining the curiously-shaped particles on their hands. Star sand are actually exoskeletons of foraminiferans (microscopic marine organisms) which have washed up by the millions for years on the island’s shores. Those who look closely enough might find some that are still alive. Source

6. Singing Beach

singing beach

Location: Manchester-by-the-Sea, Massachusetts, USA

What’s so special about it: Before you get carried away by your imagination, the sounds coming from the friction between the grains of sand in this beach are actually more of the creaky, squeaky kind than the melodic, symphonic type, which is probably how you imagine it. Though you might call this false advertising, the experience is still one-of-a-kind. That Singing Beach is still one of of North Shore’s most popular attractions attests to that. Source

7. A sandy beach in the middle of a meadow


Location: Playa De Gulpiyuri, Llanes, Spain

What’s so special about it: If you’re walking in a meadow and suddenly find yourself in a beach, it’s likely you’ve come to Playa De Gulpiyuri. Though the ocean is nowhere in sight, the beach is actually connected by a network of intricate underground waterways to the Atlantic where its water is sourced. Source

8. Pink Sand Beach


Location: Harbour Island, Bahamas

What’s so special about it: Eroded particles from red corals across the eastern coast of the Bahamas have washed to shore to give the powdery sand of Harbor island a pinkish glow. If you’re a fan of pink, this beach is the way to go. Source

9. Purple Sand Beach

Photo credit http://www.panoramio.com/photo/37836592

Location: Pfeiffer Beach, Big Sur, California, USA

What’s so special about it: Another cute-colored sand beach is found in Big Sur, California. The purple tint of the sands of Pfeiffer Beach comes from its dominant mineral quartz combined with manganese garnet deposits found in the surrounding rocks. Source

10. Bioluminescent Beach


Location: Maldives

What’s so special about it: It’s an ocean of stars! Bioluminescent phytoplankton, which glows when agitated, can be found in many shores all over the world, but it seems they’re found more often in Maldives. This amazing photo was taken by Taiwanese photographer Will Ho. Source

11. Beach of the Cathedrals


Location: Playa de las Catedrales/Praia de Augas Santas, Ribadeo, Spain

What’s so special about it: Magnificent geological formations form a cathedral-like effect across this idyllic beach in Spain. The beach can only be easily accessible during low tide. Source

12. Bowling Ball Beach

Photo credit

Location: Schooner Gulch State Beach, Mendocino County, California, USA

What’s so special about it: Large spherical rocks, like over-sized bowling balls, are scattered across the shore of this beach in Schooner Gulch. The boulders are said to have been caused by millions of years of erosion and “concretion” a rare geologic phenomenon also observed in the Moeraki and Koutu Boulders in New Zealand and Cannonball River in North Dakota. Source

13. Maho Beach

Location: Saint Mar Dr. K C Yeetin Island, Sint Maarten

What’s so special about it: With the beach’s location adjacent to the Princess Juliana International Airport, vacationers can actually jump up and touch a flying airplane. Source

14. Schoolhouse Beach


Location: Washington Island, Wisconsin, USA

What’s so special about it: If you like beaches but absolutely hate sand sticking to your feet and getting everywhere else, you’ll love Schoolhouse Beach. Instead of icky sand, it’s covered in smooth limestone rocks that were glacier-polished for thousands of years. Each small rock is a geologic treasure that anyone caught trying to take one home has to pay a steep fine. Source 

15. Vanishing Beach

Photo credit

Location: Chandipur Beach, eastern India

What’s so special about it: In the morning, the sea in Chandipur Beach vanishes completely like a miracle. It recedes up to 5 kilometers from the shore, giving visitors an opportunity to walk in the sea and explore the sea bed on foot. But once high tide kicks in, they better be back in shore, since that’s when the sea rushes back into place. This strange phenomenon happens twice a day throughout the year. Source

16. Hidden Beach

Photo credit

Location: Playa de Amor, Marieta Islands, Mexico

What’s so special about it: This idyllic beach paradise was actually created when the Mexican government in the early 1900’s made a bombsite out of the area, blasting a huge hole on the canopy of the grotto. Despite its dreadful past, we’re actually grateful — the beach looks absolutely gorgeous! Source 

17. Black Sand Beach

Photo credit

Location: Punalu’u Park, Hawaii

What’s so special about it: Sick of ordinary white sand beaches? Head down to Punalu’u Park for something entirely different. As for why the sand is colored black, we have theories. Source

18. White Sand Beach

Photo credit

Location: Hyams Beach,, New South Wales, Australia

What’s so special about it: Hyams Beach holds a Guinness Record for having the whitest sand in the world. It’s like snow in summer! Source

19. Rainbow Beach

Photo credit

Location: South-eastern Queensland, Australia

What’s so special about it: Multi-colored sand dunes surrounding the town supply Rainbow Beach with as many as 74 different colors of sand. The colorful sand dunes are a result of years of erosion and iron oxidation dating back since the Ice Age. Source

20. Round Pebble Beach


Location: Mabua Pebble Beach, Surigao City, Philippines

What’s so special about it: Instead of sand, this beach is covered with a multitude of smooth round pebbles which the waves gathered in from the sea. According to reflexologists, walking on these stones has a strong therapeutic effect on the body., which makes this beach a popular getaway for those who want to relax and rejuvenate. Source

21. Pig Beach

Photo credit

Location:  Big Major Cay, Bahamas

What’s so special about it: Big major Cay is an island in the Bahamas that’s populated by 20 or so feral pigs who are often seen lounging about and swimming in the clear waters around the island. No one really knows where they came from, but they sure are bringing more and more curious travelers to their island. Source

22. Scala Dei Turchi

Photo credit

Location: southern Sicily, Realmonte, Italy

What’s so special about it: Scala dei Turchi is a set of stairs formed out of natural white rock by years of wave action. Beach-goers are often found covered in white paste made from the mineral Marl that’s abundant in the area and is said to be good for the skin.  Source

23. Whitehaven Beach


Location: Whitsunday Island, Australia

What’s so special about it: Not only is Whitehaven Beach visually spectacular, it’s also actually awarded as the most eco-friendly beach in the world by CNN. Local sands are bright white containing a large amount of silica, which does not retain heat, enabling visitors to walk around the silky shore comfortably while barefoot on a sunny day.    Source

24. Shell Beach


Location: L’Haridon Bight,  Shark Bay, western Australia

What’s special about it: A 7 to 10 meter thick layer of cockle shells covers the entire shoreline of this fascinating beach. Due to the high salinity of the water, cockles proliferate abundantly in the absence of its natural predators, who cannot survive in such harsh environment. It is one of the only two beaches made entirely out of shells. Source


A desert that turns into a beach on certain parts of the year

Photo credit

Location: Lençóis Maranhenses National Park, Maranhão, Brazil.

What’s so special about it: Every start of the year, continuous rainfall floods the desert dunes of Lençóis Maranhenses National Park, creating a series of lovely turquoise lagoons in the white valleys of sand. The desert beach persists until it completely dries up in October. If you look closely in the water, you’ll be surprised to find a variety of fishes swimming around–a result of adaptation through the periodic drying and flooding of the desert oasis. Source

A “glacial river lagoon” with black sand

Location: Jökulsárlón Lake, southeastern Iceland

What’s special about it: Chunks of ice like huge glistening crystals scattered across the jet black bay make this natural scene seem right out of a dream. The ice comes from a nearby glacier while volcanic rock accounts for the black sand. Source

A beach covered in fish bones


Location: Salton Sea, California, USA

What’s so special about it: Other beaches are covered in glass, pebbles, and multi-colored sand, but this beach is covered in fish bones. How did that happen? Find out here.

Why is my microwave not working?

My answer to Why is my microwave not working?

Answer by KC Yee:

most common failure in microwave ovens is the electrical relay that is controlled by the control panel. The relay is a electric-mechanical device, that is no more than a controlled switch, it uses a metal piece for connection, and a spring to bounce off the metal to disconnect. This is often where it fails.

the part only costs a few $, but Unfortunately, this part is NOT user replaceable. Requires a professional service person.

Why is my microwave not working?