How people see colours

How do cones in the retina recognise colours?  

Cones are concentrated in the fovea at the centre of the retina.  Three populations of cones have three different variations of a protein, rhodopsin, which changes shape when hit by light of a particular frequency.  Rhodopsins combine with vitamin A and subtle variations in amino acids change their sensitivity to light.  

Each population responds to several photons of light of a particular range of wavelengths.  When the protein changes shape it blocks glutamine secretion, causing a silence. Look how spread out their responses are; the 'red' cones actually peak in the yellow/green wavelength.

Dogs have only two different populations of cones so they have red/green colour blindness. WE can't detect ultraviolet light, with wavelengths of 10-400 nm but hawks can, they have a fourth population of cones which respond to ultraviolet rays. Mouse urine and hair glows ultraviolet due to the presence of certain amino acids. 

Insect eyes have a similar sensitivity beyond human vision so bees can see 'nectar guides', ultraviolet indicators in flower petals.  

Kate Mosse: Five facts about the French in Languedoc

Kate Mosse: La France profonde

1. Richard Coeur de Lion couldn't speak English and he barely set foot in England, that's the revelation that Kate Mosse brought to the Cheltenham Book Festival today.  Richard was bilingual: in Langue d'Oil and Occitan.  The language of Occitan is promoted much more in schools than it used to be.

2. The French buy French wine, cheese and bread. Kate attributes this to the years of shortage in Vichy France, when people in towns relied on local farmers to stave off hunger.  In the older generation, she said, the gratitude lives on. The French prefer to do things in a French way which may not be the most efficient way. 

3. The majority of Jews in France were rescued in the South of France.  Kate has always been fascinated by the strong links between the land, its history and the people, which is portrayed in the Labyrinth trilogy.    Le chemin de la liberte provided an escape route over the Ariege Pyrenees.  The people of Launguedoc have a long history of subjection to  authority and a refusal to comply.  

4. Pretty villages in France  have hardly changed.  France is highly centralised but because of its sheer size it has a long history of independent local government.  Kate feels  French villages and towns have resisted economic change and redevelopment more effectively than the Brits. . However, some villages in the south of France have a larger population of ex-pat Brits than French people. 

5. Winters are cold in Provence.  Brits tend to forget about the Tramontane, the strong northerly  wind that chills to the bone in winter. It's not all hot sun, it's hotter in summer and cooler in winter than Britain.

Wartime poetry

Effie Roberts' poems recount the impact of war on the everyday lives of women.  Effie loses her sweetheart in WWI, marries his best friend but her poems are silenced when she loses her husband to a heart attack two years after the end of the World War II.

     A generation of women lived through the 'war to end all wars' only to experience the threat of Nazi invasion and bombardment.  Effie's poems evoke the home front: rationing, austerity, shortages, queues and recycling in Cheltenham, Gloucestershire.  

     Effie's heartfelt poems include many striking images: a football dropped from a plane with a note reporting Armistice Day, the days of freedom on Sheffield trams in early 1939 and her crushing loss in 1947.  
     A picture emerges of a seamstress who sought the best for her family, loved sunny days and desperately missed the foods and holidays that she loved. 

A Wartime Poetry Journal.

Read Effie's poems here:

Effie's poems

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