This plush, huggable sixteenth birthday dog is incredibly soft and incredibly cute, a great gift for remembering a special birthday.
This cute dog toy is a great way to commemorate a friend or family member's sixteenth birthday. Arriving in a bright, cheerful and colourful gift bag, the dog itself is super soft, great for cuddling or keeping as a gorgeous ornament on the shelf.
Buy the sixteenth birthday gift plush dog for a friend who loves collecting soft toys, ornaments, or just loves dogs.


text:
Eco - Wolves
If it feels like Eco has fallen somewhat release-quiet of late, well it's not without good reason. Until a few years ago a veritable dynamo, no trance season was quite complete without a complement of his singles. As quixotically beautiful as their titles were intriguingly cryptic & enigmatic, 'The Light In Your Eyes Went Out',
'Walkabout', 'A Million Sounds, A Thousand Smiles', 'Staring At The Sea' and dozens of others came to rank amongst trance's most imaginative and esoteric.
Most albums have 'a story', but perhaps not to quite the same degree as Eco's 'Wolves'. Dealing with (as the New Jersey-ite puts it) "a child who is no longer satisfied with the time & place he finds himself in and decides to embrace wilderness", it is, in part, an allegory of his disillusionment. Moreover though it's a concerted attempt to confront it and improve it.
Musically, the album tracks the arc of the 'Wolves' novella. Reading at roughly the same pace as it (pause-free) plays, its titles, music and lyrics, in effect, 'illustrate' the book. Using the wolf motif, it deals with the highs, lows, and varying trials and tribulations the boy faces. In doing so, it provides a rarely - if ever before – experienced adjunct to a music album. While the story is personal to Marcello, it's also one that will very likely resonate with fans within the scene.
To further the album's Odyssey-like journey to completion, Eco picked up and learnt instruments he'd never previously touched (most notably, the guitar, which is prevalent in several tracks). He was also intimately involved in all facets of the concept album: writing song lyrics, creating the artwork and clothing line, as well as curating the accompanying films, and working closely with the author of the written story. Musically, this album saw him collaborate with a wide range of talents (with artists such as Driftmoon, Jennifer Rene, Gordana Markovic, Chris Severe, and Ariah Noetzel). More often though - as the absolute master of 'Wolves' destiny - he took its work
upon himself.
01. Darkness In The Light
02. The Rain (with Ariah Noetzel)
03. Trust In The Wind (with Driftmoon)
04. Dogs
05. River Song
06. Soar
07. Slow Rising Sun (with Gordana Markovic)
08. Cloud [Part 1] (with Chris Severe)
10. If I Survive (I'll Worship The Moon)
11. No Ceilings
12. It'll All Make Sense One Day
13. Wolves
14. Running (with Jennifer Rene)
15. The Lonely Soldier

redpajama_set_name: RedPajamaCommonCrawl


Woo hoo! Reflective stuff! Ok, maybe I'm the only nerd that gets excited about bright objects. But I like wearing black when it comes to my motorcycle gear. I look good in it too, what can I say? :P But I know that I need to somehow make up for all the darkness with some bright reflectives to stay visible and safe as possible. So here's a few accessories I like that can help you too.
Wearing Hi-Viz Yellow or Orange is certainly a great way to be seen by more people. There's no guarantee that you'll be seen by every person, but certainly reduces the risks in my opinion. However, for me, the bright color isn't enough for riding at night.
It doesn't matter how bright your clothes are if they aren't reflective, I really believe in lots of reflective pieces so when light hits you it reflects.
So here are 3 reflective accessories that I wanted to share that I really think are cool to use.
They have a few different shape / pattern options. I opted for the chain links (white) and the modular kit (purple). I found mine on Amazon but you can buy them directly on their website as well. (Unfortunately they're still running an old promo code from October on the main page, so they're not on sale).
Even if you don't like these, just hop on eBay or Google and you'll find your favorite sports teams, animals, shapes, motorcycle manufacturers and more in the form of reflective decals. You're sure to find something you want to wear!
There are a lot of vest options on the market. I still love my Spectrum vests, although they did close their business this past year. The previous owner told me that it should be back next year under new management. They used a really really bright reflective tape that was Coast Guard worthy. If I do have to ride at night, I always wear my vest!
You'll find a lot of different vests to choose from, including options from the bicycling world. But as a motorcyclist I would try to find a vest that uses CE / EN Certified Fabrics (less likely to fade) and 3M Scotchlite Reflective Tape (even more visible, durable). These materials make a much brighter difference at highway speeds.
I bought neon yellow and purple. My plan is to weave them together somehow and then run them through the loops on the top of my Kriega R20 Backpack since the logos are the only reflective pieces. Sometimes I ride home at night with my backpack on so I want to add as much reflective as I can!
I bought a roll of this on Amazon so I could make my own patterns for my last helmets. I found a ton of rolls in various colors and widths there too.
I've also started a Pinterest board to collect these ideas; check them out here.
If you have any cool reflective accessories that you like using, please share!
More Birthday Loot! I forgot to post my birthday backpack; this cute Kriega R20. I currently have the R25 which I do love, but I'll admit it's a bit big on me.
For my birthday, my wonderful friend Dimitry bought me the R20. I love it! The only thing I want to change is the mostly black exterior. So I hopped onto Amazon and found reflective paracord, who knew such a thing existed?
I bought yellow and purple. I'm going to weave them together and make a little rope that runs through the loops on the top of the backpack (which are mainly there for you to add the 5 or 10L packs for extra storage).
Now I'll have some more visibility from the back (and some cute color!) while riding. I'll have a full review posted soon as well.
Thanks Kriega for making such a great little bag for me to play with.


Pluto and Charon… in color!
Where were you in 1930?
An artist's conception of New Horizons at Pluto. Credit: NASA.
The late American astronomer Clyde Tombaugh got a birthday present yesterday when NASA's New Horizons spacecraft released an image of Pluto and its moon Charon.


Generations at Regency offers activities that are stimulating and enriching to the lives of our residents. The activities promote structuring of leisure time and provide opportunities of choice, so that the residents have control of their daily lives.
Throughout the year, there are a number of social activities including cooking classes, live entertainers, or arts and crafts. Residents have also started some of their own special groups that meet weekly such as our Men's Group, Polish Club, and our Golden Girls.
Generations at Regency has hosted many special events throughout the years. We also have many special guests and entertainers who perform for us on a regular basis. Our holiday events and birthday parties are in no way ordinary – we make every special event an occasion that won't be forgotten!
We give our residents the opportunity to lead a very full and happy life here at Generations at Regency. We believe everyone should always enjoy life and have fun!


text:
Copceac (Gagaoezisch: Kıpçak) is een gemeente - met dorpsstatus - in de Moldavische bestuurlijke eenheid (unitate administrativ-teritorială) Gagaoezië. De gemeente is een exclave van Gagaoezië en wordt ingesloten door het Moldavisch arrondissement Taraclia en de Oekraïense Oblast Odessa. De gemeente telde in 2014 ruim 9.000 inwoners. De gemeente ligt niet ver van het Oekraïense dorp Tsjernevonoarmijske in rajon Bolhrad.

Bevolking
In 2014 telde de gemeente Copceac 9.138 inwoners, een daling van 4% ten opzichte van 9.551 inwoners in 2004. De gemeente had een kleine vrouwenoverschot: er woonden 4.611 vrouwen (50,5%) tegen 4.527 mannen (49,5%).

Van de bevolking was 19,9% tussen de 0-14 jaar (1.822 personen), 72,2% was tussen de 15-64 jaar (6.636 personen) en tot slot was 7,4% 65 jaar of ouder (680 personen). De grootste leeftijdscategorie vormden de 20 tot 29-jarigen met 1.928 personen, terwijl de tachtigplussers met 170 personen de kleinste leeftijdsgroep vormen.

Etniciteit
De bevolking van Copceac was - uitgezonderd van enkele minderheidsgroepen - bijna mono-etnisch Gagaoezisch: de 9.068 Gagaoezen vormden 94,94% van de bevolking in 2004. De belangrijkste minderheden waren Bulgaren (144 personen), Moldaviërs (110 personen), Russen (97 personen), Oekraïners (71 personen) en Roma (33 personen). In 2014 steeg het percentage Gagaoezen verder naar 95,5%, terwijl de overige minderheidsgroepen absoluut en relatief gezien daalden (uitgezonderd van de Russen).

Gemeente in Moldavië
Gagaoezië

redpajama_set_name: RedPajamaWikipedia


text:
Suspect wanted for hitting 74-year-old woman with car and robbing her in east Memphis
MEMPHIS, Tenn. (localmemphis.com) – Memphis Police are searching for a man they say robbed an elderly woman by running into her with a car first, then stealing her iPhone.
Police say they responded Thursday about 4:00 p.m. to the 100 block of Colonial in east Memphis. Police say the 74-year-old victim was walking nearby along Gwynne Road when she was hit from behind by a man driving a black 2004-2005 Chevy Malibu. The driver jumped out and stole the woman's pink iPhone before taking off.
The victim as taken to Regional One in non-critical condition.
Memphis Police released video of the robbery on their Facebook page.
The suspect is described as a black male wearing a red sweatshirt, blue sweatpants, black toboggan, solid white tennis shoes, and a metallic watch on his left arm.
The suspect's vehicle had damage on the front driver's side hood and damage to the rear bumper under the drive out tag.
Police say the suspect could face an attempted murder charge.
Anyone with information is asked to call Crime Stoppers at 901-528-CASH.
More Crime Stories
by Istvan Bardos / Jan 19, 2020
MEMPHIS, Tenn. (localmemphis.com) - One person is dead, and four others were injured, in a shooting early Sunday morning at a nightclub in Hickory Hill.
According to Memphis Police, the shooting happened just before 1am at Truth Night Bar at 6761 Winchester Road. A man was found shot to death, and four other men were taken to the hospital. Two of those were in critical condition, and two were non-critical.
U.S. Department says crime is down in Memphis, in part thanks to several programs aimed at the area
MEMPHIS, Tenn. (localmemphis.com) - Local law enforcement agencies are praising new numbers showing crime in most major categories has dropped for two years in a row in Memphis.
In a news conference Friday, U.S. Attorney Mike Dunavant noted multiple programs targeted to Memphis to decrease some of the most violent crimes.
Man arrested after being accused of raping woman & trying to kill her with toilet seat lid
by Kim Wheeler / Jan 17, 2020
MEMPHIS, Tenn. (localmemphis.com) - A man is in jail accused of raping a woman and trying to kill her in a vacant apartment in Whitehaven.
According to a police affidavit, the victim told investigators that while walking on January 11, she met Derrick Rice near a Citgo gas station in the 1700 block of Winchester.


text:
Trump tosses paper towels to crowd in Puerto Rico visit
"There's a lot of love in this room, a lot of love," he said, before launching the rolls into the air like a basketball player shooting a free throw.
Trump tosses paper towels to crowd in Puerto Rico visit "There's a lot of love in this room, a lot of love," he said, before launching the rolls into the air like a basketball player shooting a free throw. Check out this story on USATODAY.com: https://usat.ly/2yGAlSH
Sean Rossman, USA TODAY Published 7:36 p.m. ET Oct. 3, 2017
President Trump visited residents of Puerto Rico and tossed paper towels at the crowd. Time
With a soft flick of the wrist, President Trump cast rolls of paper towels into the eager arms of delighted Puerto Ricans on Tuesday.
At the island's Calvary Chapel, enthusiastic residents reached for the paper towels with each heave, like baseball fans stretching for a foul ball.
Trump's paper product flinging made for memorable visuals during his visit to the U.S. territory, which was ravaged by Hurricane Maria last month.
President Donald Trump tosses paper towels into a crowd as he hands out supplies at Calvary Chapel on Tuesday in Guaynabo, Puerto Rico. Trump is in Puerto Rico to survey hurricane damage. (Photo: Evan Vucci, AP)
A White House press pool report described it as a "well-staged" event, where the president was cheered amid signs that read "Proud Americans," "God Bless You Mr. President" and "Let's Make Puerto Rico Great Again."
Standing before a table of relief supplies, the president displayed a much softer demeanor than he did days earlier when he criticized the mayor of San Juan's "poor leadership ability" and lamented how the island's leaders "want everything done for them."
President Trump tosses paper towels into a crowd as he hands out supplies at Calvary Chapel on Tuesday in Guaynabo, Puerto Rico. Trump is in Puerto Rico to survey hurricane damage. (Photo: Evan Vucci, AP)
Other parts of Trump's one-day tour weren't as warm. A woman held up a sign reading, "You are a bad hombre" as the president's motorcade passed a damaged part of the island.
After Hurricane Irma swept through Florida, Trump passed out hoagies — "here's a nice one!" — and made a reference to his infamous hand size during a stop in Naples.
"They're too small," said the president, tearing through a pair of white plastic gloves.
Follow Sean Rossman on Twitter: @SeanRossman
Read or Share this story: https://usat.ly/2yGAlSH
'There was a very interesting problem': Trump adds mystery to why Pence abruptly canceled trip
Affordable Care Act threatened as Trump administration, GOP states fight US House, Democratic states in court
Donald Trump's White House is leaking - literally - on the media
Donald Trump goes after Fox News in late-night Twitter rant
The stuff of nightmares: Inside the migrant detention center in Clint, Texas
Navy's choice to head Naval Operations to step down amid call for inspector general's investigation


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Putauaki (Mt Edgecumbe), Kawerau King of the Mountain race
Putauaki (Mt Edgecumbe) towers 820 metres above the township of Kawerau at the southern end of the Rangitaiki Plains. The town was built in the early 1950s for to support the new pulp and paper mill being constructed at the same time. The Kawerau King of the Mountain race, a race from the town to near the summit of Putauaki and back, has been held every year since 1955. Information about the race, with entry forms and race results can be found on the Kawerau King of the Mountain web site.
Access to the mountain is now controlled, and a permit is required to climb the mountain. Due to safety concerns it is necessary to climb in groups of at least 4 people, and the office issuing the permits is only open on weekdays. See the Kawerau Online web site for more details of the mountain and the procedure required to obtain a permit.
Note: According to an article in The Beacon on July 15, 2022, permits to climb the mountain will not be issued until a safety review has been done and any required work completed.
Since I hadn't managed to get together a group of 4 to climb Putauaki I decided to join the race. The main conditions for entry are that you can reach the top turnaround point within 2 hours 30 minutes, and finish within 3 hours. Anyone not reaching the summit in time will be driven down by 4WD on the access road, but timing at the finish line does continue even after 3 hours. Start and finish is at Firmin Field on Waterhouse Street, with the main race starting at 12:00. In 2016 all participants reached the top point within 2 hours, but a few did take just over 3 hours to reach the finish line. The fastest runners complete the course in well under 1 hour, with a new record of 45 minutes 31 seconds being set in 2016.
The race uses separate tracks for the uphill leg and the downhill leg. The uphill leg apparently follows the normal track to the summit for most of the way, whereas the downhill leg is a very steep and slippery specially constructed track heading more or less straight down the side of the mountain. The start is about 40 metres above sea level, with the highest point reached on the run at about 780 metres. Total distance is about 7 km.
The lower part of the mountain is covered in pine forest, with the upper part covered in mostly low scrub and bushes.
Putauaki (Mt Edgecumbe) is clearly visible from almost everywhere on the Rangitaiki Plains. Entering Kawerau from the north it is very prominent.
The Rangitaiki River runs alongside Firmin Field and the adjacent Waterhouse Street Reserve, and is used for white water rafting and canoe slalom events.
The summit of Putauaki seen from Waterhouse Street Reserve, near Firmin Field.
Before the main race there is a Prince and Princess race for schoolchildren held over a much shorter course. Here leaving Firmin Field and heading up Waterhouse Street across the Tarawera River.
Firmin Field before the main race. A huge video screen, seen from the back at the far right, screens live coverage during the race. Photographers and videographers are located in several places along the route.
Drink stations along the route provide water to the participants. This one before the start of the more serious climb through radiata pine forest. The transmission towers at the summit can be seen at the top.
Looking back down the mountain the pulp and paper mill and industrial area can be seen to the right, with the township of Kawerau left of centre. Firmin Field is hidden behind the low hills on the far left.
The first glimpse of the summit after climbing through the pine plantation. This is at an elevation of about 465 metres, with more than 300 metres climb still to go..
Another 50 metres higher up and theres a good view across the Rangitaiki Plains to the Bay of Plenty, with Moutohora (Whale Island) prominent to the right.
Almost at the highest point of the race, at about 730 m asl, this is the view of the town, mill and industrial area.
A competitor taking a drink of water, having a rest, and chatting with the recently re-elected mayor of Kawerau, Malcolm Campbell, at the highest point. The mayor stayed there for the whole race before driving back down and helping with the presentation ceremony after the race.
Much of the downhill leg is very steep and slippery scoria, and could be done by crouching right down and using the shoes as skis. Wearing a pair of gloves could be recommended to avoid scoria rash.
The last checkpoint and drink station before the finish line. All the volunteers do a great job to keep the whole event running smoothly and safely. The rescue helicopter was on standby, and was used for dropping off water at a couple of the drink stations.
Ready to cross the finish line as the last one home, at just over 3 hours 6 minutes.
The prizegiving ceremony after the race. The large advertising hoarding is actually the video screen used during the race to show live coverage of the event.
The GPS tracklog shows the route followed, starting from Firmin Field on the left and turning around near the summit of Putauaki on the right.
A topographic map of the same area as shown on the GPS tracklog. The steepness of the climb is clearly visible with the close contour lines above about 300 metres above sea level.
A satellite image, from Google Maps, of the same area as above. The crater lake at the summit is in the lower right corner.
The race was walked on October 29, 2016.
This entry was posted in Walks and tagged Kawerau, King of the Mountain, Mt Edgecumbe, Putauaki, Tarawera River on 2016-10-30 by nzartig.
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2 thoughts on "Putauaki (Mt Edgecumbe), Kawerau King of the Mountain race"
Jim Bell 2020-09-08 at 13:53
I lived with my family in Kawerau from 1960-64 as a young boy. I climbed to the top 8 times as a Cub Scout. On one of our hikes, part of our troop made it to the lake and got lost on the way down and a lot of people in town spent the might hunting for us. We made it home about 4 AM. My Daddy was the electrical inspector on the new construction at Tasman papermill. We lived on Balance Street and then later on "The Plateau" on Bell Street. We were among the few Americans that wore shorts and sweaters to school and sang "God Save the Queen" at the Saturday Tarzan matinees. We traveled from the very Northern extremes to Stewart Island in the South. and saw just about everything in between. I loved New Zealand and it remains my favorite place of every destination in the world I have been. Fish and Chips for lunch at school and sledding on the steep slopes on cardboard boxes…Catching world class Rainbow Trout in pristine streams. What in incredible place. I simply loved it and still do. I am a farmer raising pecans, beef cattle and wild prairie hay. I live in heaven too!!
Jim Bell
Richards, Missouri
nzartig Post author 2020-09-08 at 15:35
Many thanks for the memories, Jim. I went to Kawerau District High School, now closed and demolished, from 1957 to 1961, but lived some distance away out in the country. So it was a long drive by school bus every day. I think I only climbed the mountain 3 times in those days. Good to hear that you still live in heaven, in Missouri!


text:
Оре́ховно — деревня в Мошенском муниципальном районе Новгородской области, административный центр Ореховского сельского поселения.

Расположение
Деревня расположена на берегу Ореховского озера.

История
Первое упоминание об Ореховне встречается в Писцовой книге Бежецкой пятины 1564 года, а в аналогичном документе 1581 года говорится уже о «Михайловском погосте в Ореховне».

Весной 1918 года в Ореховской волости установилась советская власть, в том же году был образован Ореховский волостной коллектив сочувствующих РКП(б).

С 1 января 1927 года по 20 сентября 1931 года в составе Боровичского округа Ленинградской области существовал Ореховский район с центром в усадьбе Климково.

Население

 1782 — село Ореховское — 20 дворов, 103 жителя (59 мужчин, 44 женщины)
 1880 — село Ореховно (Заболотье) — 33 двора, 59 жилых построек, 142 жителя (69 мужчин, 73 женщины)
 1911 — село Ореховно — 40 дворов, 50 жилых построек, 238 жителей (108 мужчин, 130 женщин)

Предприятия и организации
 МУСХП «Колос»
 Школа
 Детский сад
 Отделение почтовой связи

Достопримечательности
 Здание церкви, построенной А. М. Литьиновой (1807) — сейчас в нём расположен Дом культуры.
 Здание школы, построенной И. П. Дараганом (1903—1904).
 Здание усадьбы И. П. Дарагана (конец XIX века) - бывшая больница и аптечный пункт

Примечания

Литература
 Н.Владимирский. Разительные перемены // Знамя Октября. 1967. 20 сентября.
 Р.Гаврилин. История Меглинского поозерья с древнейших времён до начала XX в., на примере деревни Ягайлово Мошенского района Новгородской области // Наследники великого города: Фрагменты докладов учащихся Санкт-Петербурга на XVI городских историко-краеведческих чтениях 2006 года. СПб., 2006. Вып. 15.
 Р.Гаврилин. Из истории меглинского поозерья // София. 2007. № 1-2.

Ссылки

Населённые пункты Мошенского района


text:
\section{Introduction}\label{sec:intro}

Radio and X--ray observations of galaxy clusters prove
that thermal and non--thermal plasma components coexist in the
intracluster medium (ICM).
While X--ray observations reveal the presence of diffuse
hot gas, the existence of extended cluster--scale radio
sources in a number of galaxy clusters, well known as
{\it radio halos} and {\it relics}, prove the presence of
relativistic electrons and magnetic fields.
\\
Both radio halos and relics are low surface
brightness sources with steep radio spectra, whose linear size
can reach and exceed the Mpc scale.
Radio halos are usually located at the centre of galaxy
clusters, show a fairly regular radio morphology, and
lack an obvious optical counterpart.
A total of about 20 radio halos have been detected up to now
(Giovannini, Tordi \& Feretti \cite{giovannini99}; Giovannini \& Feretti
\cite{gf02}; Kempner \& Sarazin \cite{kempner01};
Bacchi et al. \cite{bacchi03}). Relics are usually found at
the cluster periphery, their radio emission is highly polarized
(up to $\sim$ 30\%), and shows a variety of radio morphologies,
such as sheet, arc, toroids. At present
a total of $\sim$ 20 relics (including candidates) are known
(Kempner \& Sarazin \cite{kempner01}; Giovannini \& Feretti
\cite{gf04}).
\\
\\
Evidence in the optical and X--ray bands has been
accumulated in favour of the hierarchical formation of galaxy clusters
through merging processes (for a collection of reviews on this subject
see Feretti, Gioia \& Giovannini 2002), and this
has provided insightful pieces of information in our understanding of
radio halos. It is not clear whether all clusters with signatures
of merging processes also possess a radio halo; on the other hand,
all clusters hosting a radio halo show sub--structures in the X--ray emission,
and the most powerful radio halos are hosted in clusters
which most strongly depart from virialization (Buote \cite{buote01}).
Giovannini et al. (1999) showed that in the redshift interval 0 -- 0.2
the detection rate of cluster radio halos increases with increasing X--ray
luminosity, which suggests a connection with the gas temperature and cluster mass.
\\
\\
The very large extent of radio halos poses the question of their origin,
since the diffusion time the relativistic electrons need to cover the
observed Mpc size is 30 -- 100 times longer than their radiative lifetime.
Two main possibilities have been investigated so far: ``primary models'', in which
particles are in--situ re--accelerated in the ICM, and ``secondary models''
in which the emitting electrons are secondary products of hadronic collisions
in the ICM (for reviews on these models see Blasi \cite{blasi04};
Brunetti \cite{brunetti03} and \cite{brunetti04}; Ensslin \cite{ensslin04};
Feretti \cite{feretti03}; Hwang \cite{hwang04}; Sarazin \cite{sarazin02}).
Cluster mergers are among the most energetic events in the Universe, with
an energy release up to 10$^{64}$ erg, and a challenging question is if at
least a fraction of such energy may be channelled into particle reacceleration
(e.g. Tribble \cite{tribble93}).
Indeed observational support (for a review see Feretti \cite{feretti03}) is now
given to the particle re--acceleration model, which assumes that the
radiating electrons are stochastically re--accelerated by turbulence in the
ICM and that the bulk of this turbulence is injected during cluster mergers
(Brunetti et al. \cite{brunetti01}; Petrosian \cite{petrosian01};
Fujita, Takizawa \& Sarazin \cite{fujita03};
Brunetti et al. \cite{brunetti04b}).
\\
\\
Although the physics of particle re--acceleration by turbulence has been
investigated in some detail and the model expectations seem to reproduce
the observed radio features, only recently statistical calculations
in the framework of the re--acceleration model have been carried out by
Cassano \& Brunetti (\cite{cassano05}, hereinafter CB05).
Making use of semi--analytical calculations they estimated the energy of turbulence
injected in galaxy clusters through cluster mergers, and derived the
expected occurrence of {\it giant}\footnote{Linear size  $\ge$ 1 Mpc as defined in CB05, with
H$_0$=50 ~km~s$^{-1}$~Mpc$^{-1}$.
This size corresponds to \raise 2pt \hbox {$>$} \kern-1.1em \lower 4pt \hbox {$\sim$} 700 kpc with the cosmology assumed in
this paper, i.e. $H_0 =70$~km~s$^{-1}$~Mpc$^{-1}$, $\Omega_m$=0.3 and
$\Omega_{\Lambda}$=0.7. } radio halos as a function of the mass
and dynamical status of the clusters in the framework of the merger--induced
particle re--acceleration scenario.
\\
The most relevant result of those calculations is that the occurrence of giant
radio halos increases with the cluster mass. Furthermore, the expected fration
of clusters with giant radio halos at z$\le$ 0.2 can be reconciled with the
observed one (Giovannini et al. \cite{giovannini99}) for viable values of the
model parameters.
\\
Cassano, Brunetti \& Setti (\cite{cassano04}, hereinafter CBS04) and
Cassano, Brunetti \& Setti (\cite{cassano06}, hereinafter CBS06) showed
that the bulk of giant radio halos
are expected in the redshift range $z\sim 0.2 \div 0.4$
as a result of two competing effects, i.e. the decrease of the fraction of clusters
with halos in a given mass range and the increase of the volume of the Universe with
increasing redshift. Given that inverse Compton losses increase with  the redshift,
it is expected that powerful giant radio halos at $z>0.2$ are preferentially
found in massive clusters ($M \sim 2-3 \times 10^{15}M_{\odot}$)
undergoing merging events. In particular, it is expected that
a fraction of 10 -- 35 \% of clusters in this redshift interval and mass range
may host a giant radio halo.
\\
\\
With the aim to investigate the connection between cluster mergers and the
presence of cluster--type radio sources, in particular to derive
the fraction of massive galaxy clusters in the range 0.2 $<$ z $<$ 0.4
hosting a radio halo and constrain the predictions of the re--acceleration
model in the same redshift interval, we undertook an observational
study using the Giant Metrewave Radio Telescope (GMRT, Pune,
India) at 610 MHz. Our project will be presented here and in future papers,
and will be referred to as the GMRT Radio Halos Survey.
\\
Here we report the results on 11 galaxy clusters observed with the GMRT in
January 2005. The paper is organised as follows:
in Section \ref{sec:sample} we present the sample of galaxy
clusters; the radio observations are described in Section \ref{sec:obs};
the analysis of our results and a brief discussion are given in
Section \ref{sec:results} and \ref{sec:discussion} respectively.
\\
\\

\section{The cluster sample}\label{sec:sample}

\begin{table*}[t]
\label{tab:sample1}
\caption[]{Cluster sample from the REFLEX catalogue.}
\begin{center}
\begin{tabular}{rrccccrcc}
\hline\noalign{\smallskip}
REFLEX Name   & Alt. name & RA$_{J2000}$ &  DEC$_{J2000}$ & z &  L$_{\rm X}$(0.1--2.4 keV)
& M$_{\rm V}$ & R$_{\rm V}$  \\
              &           &              &                &   & $10^{44}$ erg s$^{-1}$
& 10$^{15}$M$_{\odot}$ & Mpc  \\
\noalign{\smallskip}
\hline\noalign{\smallskip}
$^{\surd}$ RXCJ\,0003.1$-$0605 & A\,2697 &  00 03 11.8 &  $-$06 05 10 & 0.2320 &   6.876
& 1.68 & 2.70    \\
$^{\star}$ RXCJ\,0014.3$-$3023 & A\,2744 &  00 14 18.8 &  $-$30 23 00 & 0.3066 &  12.916
& 2.58 & 2.99    \\
$^{\surd}$ RXCJ\,0043.4$-$2037 & A\,2813 &  00 43 24.4 &  $-$20 37 17 & 0.2924 &   7.615
& 1.80 & 2.67    \\
$^{\surd}$ RXCJ\,0105.5$-$2439 & A\,141 &  01 05 34.8 &  $-$24 39 17 & 0.2300 &   5.762
& 1.50 & 2.60    \\
$^{\surd}$ RXCJ\,0118.1$-$2658 & A\,2895 &  01 18 11.1 &  $-$26 58 23 & 0.2275 &   5.559
& 1.45 & 2.58    \\
$^{\surd}$ RXCJ\,0131.8$-$1336 & A\,209 &  01 31 53.0 &  $-$13 36 34 & 0.2060 &   6.289
& 1.58 & 2.69    \\
$^{\surd}$ RXCJ\,0307.0$-$2840 & A\,3088 &  03 07 04.1 &  $-$28 40 14 & 0.2537 &   6.953
& 1.69 & 2.67    \\
           RXCJ\,0437.1$+$0043 &  $-$  &  04 37 10.1 &  $+$00 43 38 & 0.2842 &   8.989
& 2.02 & 2.79    \\
$^{\surd}$ RXCJ\,0454.1$-$1014 & A\,521 &  04 54 09.1 &  $-$10 14 19 & 0.2475 &   8.178
& 1.89 & 2.78    \\
           RXCJ\,0510.7$-$0801 &  $-$  &  05 10 44.7 &  $-$08 01 06 & 0.2195 &   8.551
& 1.95 & 2.86    \\
$^{\surd}$ RXCJ\,1023.8$-$2715 & A\,3444 &  10 23 50.8 &  $-$27 15 31 & 0.2542 &  13.760
& 2.69 & 3.12    \\
$^{\surd}$ RXCJ\,1115.8$+$0129 &  $-$  &  11 15 54.0 &  $+$01 29 44 & 0.3499 &  13.579
& 2.67 & 2.95    \\
$^{\star}$ RXCJ\,1131.9$-$1955 & A\,1300 &  11 31 56.3 &  $-$19 55 37 & 0.3075 &  13.968
& 2.72 & 3.04    \\
           RXCJ\,1212.3$-$1816 &  $-$  &  12 12 18.9 &  $-$18 16 43 & 0.2690 &   6.197
& 1.56 & 2.58    \\
$^{\surd}$ RXCJ\,1314.4$-$2515 &  $-$  &  13 14 28.0 &  $-$25 15 41 & 0.2439 &  10.943
& 2.30 & 2.98    \\
$^{\surd}$ RXCJ\,1459.4$-$1811 & S\,780 &  14 59 29.3 &  $-$18 11 13 & 0.2357 &  15.531
& 2.92 & 3.24    \\
           RXCJ\,1504.1$-$0248 &  $-$  &  15 04 07.7 &  $-$02 48 18 & 0.2153 &  28.073
& 4.37 & 3.75    \\
$^{\surd}$ RXCJ\,1512.2$-$2254 &  $-$  &  15 12 12.6 &  $-$22 54 59 & 0.3152 &  10.186
& 2.19 & 2.81    \\
           RXCJ\,1514.9$-$1523 &  $-$  &  15 14 58.0 &  $-$15 23 10 & 0.2226 &   7.160
& 1.73 & 2.74    \\
$^{\star}$ RXCJ\,1615.7$-$0608 & A\,2163 &  16 15 46.9 &  $-$06 08 45 & 0.2030 &  23.170
& 3.84 & 3.62    \\
$^{\surd}$ RXCJ\,2003.5$-$2323 &  $-$  &  20 03 30.4 &  $-$23 23 05 & 0.3171 &   9.248
& 2.05 & 2.75    \\
           RXCJ\,2211.7$-$0350 &  $-$  &  22 11 43.4 &  $-$03 50 07 & 0.2700 &   7.418
& 1.77 & 2.69    \\
$^{\surd}$ RXCJ\,2248.5$-$1606 & A\,2485 &  22 48 32.9 &  $-$16 06 23 & 0.2472 &   5.100
& 1.37 & 2.50    \\
$^{\surd}$ RXCJ\,2308.3$-$0211 & A\,2537 &  23 08 23.2 &  $-$02 11 31 & 0.2966 &  10.174
& 2.19 & 2.85    \\
$^{\surd}$ RXCJ\,2337.6+0016   & A\,2631 &  23 37 40.6 &  $+$00 16 36 & 0.2779 &   7.571
& 1.79 & 2.69    \\
$^{\surd}$ RXCJ\,2341.2$-$0901 & A\,2645 &  23 41 16.8 &  $-$09 01 39 & 0.2510 &   5.789
& 1.49 & 2.57    \\
$^{\surd}$ RXCJ\,2351.6$-$2605 & A\,2667 &  23 51 40.7 &  $-$26 05 01 & 0.2264 &  13.651
& 2.68 & 3.16    \\
\noalign{\smallskip}
\hline
\end{tabular}
\end{center}
Symbols are as follows: $^{\surd}$ marks the clusters observed by us with the
GMRT as part of our radio halo survey;
$^{\star}$ marks the clusters with radio halo known from the literature
(A\,2744 Govoni et al. \cite{govoni01}; A\,1300 Reid et al. \cite{reid99};
A\,2163 Herbig \& Birkinshaw \cite{herbig94} and Feretti et al.
\cite{feretti01}). All the remaining clusters are part of the GMRT cluster
Key Project (P.I. Kulkarni).
\end{table*}

In order to obtain a statistically significant sample of clusters
suitable for our aims, we based our selection on the ROSAT--ESO
Flux Limited X--ray (REFLEX) galaxy cluster catalogue
(B{\"o}hringer et al. \cite{boeringer04}) and on the extended
ROSAT Brightest Cluster Sample (BCS)
catalogue (Ebeling et al. \cite{ebeling98} \& \cite{ebeling00}).
Here we will concentrate on the REFLEX sample, which was
observed with the GMRT in January 2005 (present paper, see next Section),
in October 2005 and August 2006 (Venturi et al., in preparation).
\\
From the REFLEX catalogue we selected all clusters satisfying the following
criteria:

\begin{itemize}
\item[1)] L$_{\rm X}$(0.1--2.4 keV) $>$ 5 $\times$ 10$^{44}$ erg s$^{-1}$;

\item[2)] 0.2 $<$ z $<$ 0.4;

\item[3)] $-$30$^{\circ}$ $<$ $\delta$ $<$ +2.5$^{\circ}$.
\end{itemize}

The lower limit of $\delta=-30^{\circ}$ was chosen
in order to ensure a good u--v coverage with the GMRT, while the value of
$\delta=+2.5^{\circ}$ is the REFLEX
upper limit.
\\
The limit in X--ray luminosity is aimed at selecting
massive clusters, which are expected to host giant radio halos
(CBS04, CB05 and references therein). It corresponds to a lower limit
in the virial mass of M$_{\rm V}~>~ 1.4\times10^{15} M_{\odot}$
if the L$_{\rm X}$ -- M$_{\rm V}$ derived in CBS06 is assumed.
We point out that the L$_{\rm X}$ -- M$_{\rm V}$ correlation in CBS06 has
a statistical dispersion
of $\sim$ 30\%. This error dominates over the systematic additional
uncertainty introduced by the fact that the correlation was obtained
using the z $<$ 0.2 cluster sample in Reiprich \& B{\"o}hringer
(\cite{reiprich02}).
\\
We obtained a total of 27 clusters. The source list is
reported in Table 1,
where we give (1) the REFLEX name, (2) alternative name from other catalogues,
(3) and (4) J2000 coordinates, (5) redshift, (6) the X--ray luminosity in the
0.1--2.4 keV band, (7) and (8) estimates for the virial mass M$_{\rm V}$
and virial radius R$_{\rm V}$ respectively (from the
L$_{\rm X}$ -- M$_{\rm V}$ correlation derived in CBS06).
\\
The location of the 27 clusters of the sample in the L$_{\rm X}$--z
plane for the whole REFLEX catalogue is reported in Fig. \ref{fig:fzx}.
\begin{figure}
\centering
\includegraphics[angle=0,width=8.5cm]{fig1.ps}
\caption{L$_x$--z plot (0.1--2.4 KeV) for the REFLEX clusters. Open red
circles show the clusters selected for the GMRT observations of the present
project (marked with the symbol $\surd$ in Table 1; see Section \ref{sec:obs}
for details); filled blue triangles indicate those clusters
(marked with $^{\star}$
in Table 1) which are known to host a radio halo from the literature,
i.e. A\,2744 (Govoni et al. \cite{govoni01}), A\,1300 (Reid et al.
\cite{reid99}) and A\,2163 (Herbig \& Birkinshaw \cite{herbig94}; Feretti
et al. \cite{feretti01}); filled green squares indicate the clusters of the
sample belonging to the GMRT Cluster Key Project (P.I. Kulkarni).
The light blue dashed region is the one surveyed in
our project.}
\label{fig:fzx}
\end{figure}

\section{Radio observations}\label{sec:obs}

From the sample given in Table 1 we selected all clusters
with no radio information available in the literature at the time
our GMRT proposal was written. We also excluded all clusters belonging
to the GMRT Cluster Key Project (P.I. Kulkarni), and remained with
a total of 18 clusters, marked with the symbol $\surd$ in
Table 1.
\\
From the list of marked clusters, 11 were given higher priority and
were observed with the GMRT during a 27--hour run allocated in January 2005.
Table \ref{tab:obs} reports the following information: cluster name,
half power beamwidth (HPWB) of the full array of the observations (arcsec),
total time on source (minutes) and rms (1$\sigma$ in $\mu$Jy b$^{-1}$)
in the full resolution image.
\\
Five clusters listed in Table 1 were observed with the GMRT in
a second observing run carried out in October 2005, i.e. A\,2813, A\,2485,
A\,2895, RXCJ\,1115.8+0129 and RXCJ\,1512.2--2254; finally the two remaining
clusters A\,2645 and A\,2667 will be observed in August 2006.
They will all be presented in a future paper (Venturi et al.
in preparation).
\\
\begin{table*}
\caption[]{GMRT observations.}
\begin{center}
\begin{tabular}{lccc}
\hline\noalign{\smallskip}
Cluster  & Beam, PA  & Obs. time    &   rms      \\
          &  (full array) $^{\prime \prime} \times^{\prime \prime}$, $^{\circ}$&
min &  $\mu$Jy b$^{-1}$\\
\noalign{\smallskip}
\hline\noalign{\smallskip}
A\,2697             &  8.5$\times$5.0, --83 &  90  &  80   \\
A\,141              &  7.7$\times$7.4, 75   & 150  &  100  \\
A\,209              &  8.0$\times$5.0, 64   & 240  &  60   \\
A\,3088             &  8.0$\times$7.0, 40   & 190  &  65   \\
A\,521              &  8.6$\times$4.0, 57   & 210  &  35   \\
A\,3444             &  7.6$\times$4.9, 19   & 120  &  67   \\
RXCJ\,1314.4--2515  &  8.0$\times$5.0  15   & 150  &  65   \\
S\,780              &  7.5$\times$5.0  25   &  80  &  70   \\
RXCJ\,2003.5--2323  &  6.9$\times$5.0, --3  & 240  &  40   \\
A\,2537             &  10.3$\times$6.0  67  & 150  &  60   \\
A\,2631             &  9.2$\times$6.3 --77  & 240  &  50   \\
\hline{\smallskip}
\end{tabular}
\end{center}
\label{tab:obs}
\end{table*}

The observations were carried out at 610 MHz, using simultaneously
two 16 MHz bands (upper side band, USB, and lower side band, LSB),
for a total of 32 MHz. Left and
right polarization were recorded for each band.
The observations
were carried out in spectral line mode, with 128 channels each
band, and a spectral resolution of 125 kHz/channel.
The data reduction and analysis were carried out with the NRAO
Astronomical Image Processing System (AIPS) package.
In order to reduce the size of the dataset, after bandpass calibration
the central 94 channels were averaged to 6 channels of $\sim$ 2 MHz each.
For each source the USB and LSB datasets, as well as the datasets
taken in different days, were calibrated and reduced separately,
then the final images from each individual dataset were combined in the
image plane to obtain the final image. Wide--field imaging
was adopted in each step of the data reduction.
\\
For each cluster we produced images over a wide range of resolutions,
in order to fully exploit the information GMRT can provide.
We point out that the nominal largest detectable structure provided
by the GMRT at 610 MHz is 17$^{\prime}$. This value ensures the possible
detection of the extended radio sources we are searching for,
since  the angular scale covered by a 1 Mpc--size structure is
$\sim~5^{\prime}$ at z=0.2 and $\sim~3^{\prime}$ at z=0.4.
\\
The sensitivity of our
observations (1$\sigma$ level) is in the range 35 -- 100 $\mu$Jy for
the full resolution images (see Table \ref{tab:obs}), which were
obtained by means of uniform weighting.
The spread in the noise level depends most critically
on the total time on source, on the total bandwidth available (in few
cases only one portion of the band provided useful data,
see individual clusters in \textsection \ref{sec:results}),
and on the presence of strong sources in  the imaged field.
Slightly lower values for the noise level are obtained for the low resolution
images (see Section \ref{sec:results} and figure captions), which were made
using natural weighting.
\\
The average residual amplitude errors in our data are of the order of
\raise 2pt \hbox {$<$} \kern-1.1em \lower 4pt \hbox {$\sim$}$~$5\%.
\\

\section{Results}\label{sec:results}

\medskip\noindent
\begin{table*}[t]
\caption[]{Parameters of the extended cluster radio sources.}
\begin{center}
\begin{tabular}{lcrclrl}
\hline\noalign{\smallskip}
Cluster & Source Type & S$_{\rm 610~MHz}$ & logP$_{\rm 610~MHz}$ &  LAS & LLS & L$_1$/L$_2$    \\
        &             & mJy               &  W Hz$^{-1}$         & arcmin & kpc &     \\
\noalign{\smallskip}
\hline\noalign{\smallskip}
A\,209           & Giant Halo &   24.0 $\pm$ 3.6  &  24.46  & $\sim$ 4 & $\sim$  810 & $\sim$ 2   \\
A\,521           & Relic      &   41.9 $\pm$ 2.1  &  24.91  & $\sim$ 4 & $\sim$  930 & $\sim$ 4.5 \\
RXCJ\,1314.4--2515  & Western Relic &   64.8 $\pm$ 3.2 &  25.03 & $\sim$ 4   & $\sim$  910 & $\sim$ 3 \\
                  & Eastern Relic &   28.0 $\pm$ 1.4 &  24.67 & $\sim$ 4   & $\sim$  910 & $\sim$ 4.3 \\
                  & Halo          &   10.3 $\pm$ 0.3  &  24.22  & $\sim$ 2 & $\sim$  460 & $\sim$ 1.5 \\
RXCJ\,2003.5--2323  & Giant Halo  &   96.9 $\pm$ 5.0  &  25.49  & $\sim$ 5   & $\sim$ 1400 & $\sim$ 1.3 \\
A\,3444   & Central Galaxy        &   16.5 $\pm$ 0.8  &  24.51  & $\sim$0.7  & $\sim$  165 & $\sim$ 1.4  \\
          & surrounding Halo      &   10.0 $\pm$ 0.8 &   24.29  & $\sim$1.5  & $\sim$  350 & $\sim$ 1.4  \\
\hline{\smallskip}
\end{tabular}
\end{center}
\label{tab:param}
\end{table*}
\\
Cluster scale radio emission either in the form of radio halo or relic
was detected in 4 clusters of the sample (\textsection \ref{sec:halos});
in one cluster extended emission was found around the dominant
galaxy (\textsection \ref{sec:minihalo});
for the remaining six clusters no hint of extended emission is present at
the sensitivity level of the observations (\textsection \ref{sec:noext}).
Details on each cluster are given in this Section. In Appendix A we report the
610 MHz radio contours within the virial radius for all the observed clusters.
All the images were convolved with a HPWB of 15.0$^{\prime \prime} \times
12.0^{\prime \prime}$, except  for A\.209, RXCJ\,1314.4--2515 and
RXCJ\,2003.5--2323 where a different resolution was chosen in
order to complement the information provided in Figs. 2, 3, 4, 5 and 6.
Table \ref{tab:param}  reports the
observational information for the detected cluster--scale radio
sources. The last column in the table, L$_1$/L$_2$, provides the ratio
between the major (LAS) and minor axis of the extended emission.
The linear size and flux densities were derived from the
3$\sigma$ contour level.

\begin{figure*}
\hspace{0.5truecm}\includegraphics[angle=0,width=7.6cm, height=6.5cm]{fig2a.ps}
\hspace{1.5truecm}\includegraphics[angle=0,width=7.2cm, height=6.5cm]{fig2b.ps}
\caption{Left -- GMRT 610 MHz radio contours for the A\,209 cluster
superposed on the POSS--2 optical plate.
The 1$\sigma$ level in the image is 60 $\mu$Jy b$^{-1}$. Contours are
0.3$\times(\pm$ 1,2,4,8,16...) mJy b$^{-1}$. The
HPWB is $8.0^{\prime\prime} \times 5.0^{\prime\prime}$, p.a.
$64^{\circ}$. Right -- Natural weighted image of the same sky region at
the resolution of $18.0^{\prime\prime} \times 17.0^{\prime\prime}$, p.a.
$0^{\circ}$. The rms (1$\sigma$) in the image is 60 $\mu$Jy b$^{-1}$,
contours are 0.18$\times(\pm$ 1,2,4,8,16...) mJy b$^{-1}$.}
\label{fig:a209_opt}
\end{figure*}

\subsection{Clusters with halos, giant halos and relics}\label{sec:halos}

\subsubsection{Abell 209}

Abell 209 (RXCJ\,0131.8--1336) is a richness R=3 cluster at
z=0.2060 (1$^{\prime\prime}$=3.377 kpc). A high
X--ray temperature is reported in the literature.
Rizza et al. (\cite{rizza98}) estimated a mean gas
temperature of kT$\sim$10 keV from the ROSAT
X--ray luminosity; this
value was confirmed by Mercurio et al. (\cite{mercurio04a})
from the analysis of {\it Chandra} archive data.
\\
The cluster has been extensively studied at optical (Mercurio et al.
\cite{mercurio03}, Mercurio et al. \cite{mercurio04a} and \cite{mercurio04b},
Haines et al.  \cite{haines04}), and X--ray wavelenghts (ROSAT--HRI,
Rizza et al. \cite{rizza98}, Mercurio et al. \cite{mercurio04a}).
These studies show that A\,209 is far from a relaxed dynamical stage, and
it is undergoing a strong dynamical evolution.
In particular the X--ray and the optical data suggest that A\,209 is
experiencing a merging event between two or more components.
\\
Mercurio et al. (\cite{mercurio03}) provided an estimate of the virial
mass of the cluster, $M_{\rm V} = 2.25^{+0.63}_{-0.65}\times 10^{15}M_{\odot}$,
consistent with our estimate given in Table 1 if we account for the
uncertainty of our value (see Sect. \ref{sec:sample}).
\\
The cluster merging scenario is confirmed by the weak lensing analysis
carried out by Dahle et al. (\cite{dahle02}), who found two significant peaks
in the mass distribution of the cluster: the largest one is close to the central
cD galaxy, and the secondary mass peak is located at about 5 arcmin
north of the cluster centre and associated to a peak in the optical galaxy
distribution.
\\
\\
610 MHz contours of the A\,209 emission within the virial radius
are given in Fig. \ref{fig:a209_lr}, while  Fig. \ref{fig:a209_opt}
shows the central part of the field at two different resolutions
superposed on the POSS--2 image. Inspection of Fig. \ref{fig:a209_lr}
and of the right panel in  Fig. \ref{fig:a209_opt}
coupled with flux density measurements, suggests the presence
of extended emission around the individual central cluster
radio galaxies.
\\
In order to highlight such emission we subtracted all the individual
sources visible in the full resolution image from the u--v data, and
convolved the residuals with a
HPBW with size $32.0^{\prime\prime} \times 30.0^{\prime\prime}$.
The image is reported in Fig. \ref{fig:a209_halo}.
\begin{figure}
\hspace{0.8truecm}\includegraphics[angle=0,width=7.2cm, height=6.7cm]{fig3.ps}
\caption{Radio contours over grey scale of the A\,209 cluster
radio halo after subtraction of the individual radio sources (see left panel
of Fig. \ref{fig:a209_opt} and Sect. 4.1.1 in the text). The resolution of this
image is $32.0^{\prime\prime} \times 30.0^{\prime\prime}$,
p.a. $30^{\circ}$. The rms (1$\sigma$) in the image is 0.15 mJy b$^{-1}$,
contours are 0.35$\times(\pm$ 1,2,4,8,16...) mJy b$^{-1}$.}
\label{fig:a209_halo}
\end{figure}
The adopted procedure indeed confirms the existence of cluster
scale extended emission. The possible presence of a radio halo in
A\,209 was suggested by Giovannini et al. (\cite{giovannini99})
from inspection of the NRAO VLA Sky Survey (NVSS), and confirmed
in Giovannini et al. (\cite{gg06}) on the basis of 1.4 GHz VLA observations.
Our GMRT image in Fig. \ref{fig:a209_halo}
is in partial agreement with the size and morphology of the VLA 1.4 GHz
image shown by those authors. The largest angular size (LAS)
is $\sim 4^{\prime}$, i.e. $\sim$ 810 kpc, therefore
we classify the source as a {\it giant} radio halo. Its total
flux density, measured after subtraction of the individual radio sources
(see left panel of Fig. \ref{fig:a209_opt}) is
S$_{\rm 610~MHz} = 24.0 \pm 3.6$ mJy, which implies a total radio power of
logP$_{\rm 610~MHz}$ (W/Hz)= 24.46.
The difficulty in subtracting the extended individual sources (in particular
the head--tail radio galaxy located just South of the cluster centre) reflects
both in the large error associated with the flux density measurement,
and in the unusual brightness distribution of the radio halo, characterised
by two peaks of emission.
\\
Further observations are already in progress with the GMRT, in
order to better image and study this source.

\subsubsection{Abell 521}

A detailed study of A\,521 (RXCJ\,0454.1--1014, z=0.2475,
1$^{\prime\prime}$=3.875 kpc) has already been published by Giacintucci et
al. (\cite{giacintucci06}). This merging cluster hosts a
radio relic located at the border of the X--ray emission.
We discussed the origin of this source in the light of current scenarios
for the formation of radio relics, i.e.
acceleration of electrons from the thermal pool or compression
of fossil radio plasma, both through merger shock waves.
We refer to that paper for the images and radio information
and will include A\,521 in the discussion in Section \ref{sec:discussion}.
All values and observational parameters reported in
Table \ref{tab:obs} and \ref{tab:param} are taken from Giacintucci
et al. (\cite{giacintucci06}).

\subsubsection{RXCJ\,1314.4$-$2515}

\begin{figure*}
\centering
\hspace{-0.5truecm}\includegraphics[angle=0,width=7.4cm, height=6.4cm]{fig4a_babb.ps}
\hspace{1truecm}\includegraphics[angle=0,width=8cm, height=6.5cm]{fig4b.ps}
\caption{Left --
GMRT 610 MHz radio contours for the cluster RXCJ\,1314.4--2515
superposed on the POSS--2 optical plate.
The 1$\sigma$ level in the image is 60 $\mu$Jy b$^{-1}$.
Contours are 0.18$\times(\pm$1,2,4,8,16...)  mJy b$^{-1}$. The
HPWB is $8.0^{\prime\prime} \times 5.0^{\prime\prime}$, p.a.
$15^{\circ}$. The western and the eastern relics are labelled
as E--R and W--R respectively, and the individual point sources
in the relics/halo region are indicated as A and B.
Right -- GMRT 610 MHz radio contours for the cluster RXCJ\,1314.4--2515
superposed on the POSS--2 optical plate.
The 1$\sigma$ level in the image is 60 $\mu$Jy b$^{-1}$.
Contours are 0.2$\times(\pm$1,2,4,8,16...) mJy b$^{-1}$. The
HPWB is $20.0^{\prime\prime} \times 15.0^{\prime\prime}$, p.a.
$39^{\circ}$ The western and the eastern relics are labelled
as E--R and W--R respectively, RH indicates the radio halo, and
the individual point sources in the relics/halo region are
indicated as A and B.}
\label{fig:rxcj1314_rel2}
\end{figure*}

Evidence of a disturbed dynamical status for the cluster
RXCJ\,1314.4$-$2515 (z=0.2439, 1$^{\prime\prime}$=3.806 kpc)
is reported in the literature. The redshift distribution of the
cluster galaxies clearly shows a bimodal structure,
with two peaks separated in velocity space by $\sim$ 1700 km s$^{-1}$
(Valtchanov et al. \cite{valtchanov02}). The X--ray morphology of the
cluster is also bimodal, and it is elongated along the
E--W direction, the western peak being the brightest
(Valtchanov et al. \cite{valtchanov02}).
\\
This cluster was observed with the VLA at 1.4 GHz by Feretti
et al. (\cite{feretti05}), who revealed the presence of a radio halo at the
cluster centre and two peripheral sources, which they classified as relics.
\\
Fig. \ref{fig:rxcj1314_lr} reports the contour image of our 610 MHz
observations at the resolution of $15.0^{\prime\prime}
\times 13.0^{\prime\prime}$ within the virial radius. The central part
of the cluster is given in the left and right panel of
Fig. \ref{fig:rxcj1314_rel2}, both superposed on the POSS--2 plate.
The left panel shows the full resolution image,
while in the right panel lower resolution contours are displayed.
Fig. \ref{fig:rxcj1314_halo_asca} shows the same region
overlaid on the X--ray ASCA image.
Our images confirm that RXCJ\,1314.4--2515 has a complex radio morphology,
with the presence of three different regions of extended emission on the cluster
scale.
\begin{figure}\label{fig:rxcj1314_halo_asca}
\centering
\hspace{-0.5truecm}\includegraphics[angle=0,width=8.0cm]{fig5_babb.ps}
\caption{GMRT 610 MHz radio contours for the cluster
RXCJ\,1314.4--2515 superposed on the X--ray archive ASCA image (colour).
The 1$\sigma$ level in the image is 60 $\mu$Jy b$^{-1}$.
Contours are 0.18$\times(\pm$1,2,4,8,16...) mJy b$^{-1}$. The
HPWB is $25.0^{\prime\prime} \times 22.0^{\prime\prime}$, p.a.
$15^{\circ}$.}
\label{fig:rxcj1314_halo_asca}
\end{figure}
\\
Two parallel features are easily visible in Figs. \ref{fig:rxcj1314_lr},
\ref{fig:rxcj1314_rel2} and \ref{fig:rxcj1314_halo_asca}.
They are separated by $\sim 6^{\prime}$ and extend in the  SE--NW direction
for approximately 4$^{\prime}$ (i.e. $\sim$ 910 kpc at the cluster redshift).
The remarkable superposition of the low resolution radio image with the
ASCA image in Fig. \ref{fig:rxcj1314_halo_asca} clearly
shows that these two sources are located at the border of the detected
X--ray emission.
\\
The overall morphology of these two features, coupled with their
location with respect to the intracluster gas, suggest that they
are radio relics, as also discussed in Feretti et al. (\cite{feretti05}),
who ruled out any association with individual galaxies.
In the following we will
refer to the eastern and the western relics as E--R and
W--R respectively, as also labelled in Fig.
\ref{fig:rxcj1314_rel2}.
The morphology and flux density ratio of the two relics are
consistent with the 1.4 GHz data in Feretti et al. (\cite{feretti05}).
Their flux densities at 610 MHz are S$_{\rm 610~MHz} = 64.8 \pm 3.2$  mJy and
S$_{\rm 610 MHz} = 28.0 \pm 1.4$ mJy for W--R and E--R respectively.
The value given for E--R does not include the southernmost pointlike source
A (Fig. \ref{fig:rxcj1314_rel2}).
In order to derive the total spectral index of W--R and E--R between
1.4 GHz and 610 MHz we included also the contribution of source A to the
flux density of
E--R, for a consistent comparison with Feretti et al. (\cite{feretti05}), and
obtained 32.8 mJy. Our flux density measurements lead to the same
value for the spectral index in both features. In particular,
$\alpha_{\rm 610~MHz}^{\rm 1.4~GHz}$(W--R) = 1.40 $\pm$ 0.09 and
$\alpha_{\rm 610~MHz}^{\rm 1.4~GHz}$(E--R) = 1.41 $\pm$ 0.09.
\\
\\
Figs. \ref{fig:rxcj1314_rel2} (right panel)
and \ref{fig:rxcj1314_halo_asca}
show that extended emission is present in the region between
W--R and E--R, consistent with the 1.4 GHz VLA images in Feretti
et al. (\cite{feretti05}), who classified
this feature as a radio halo. This source is referred to as RH in the right
panel of Fig. \ref{fig:rxcj1314_rel2}. It is spatially coincident with the
bulk of the optical galaxies (see Valtchanov et al. \cite{valtchanov02}) and
its largest angular size is $\sim~2^{\prime}$, corresponding to 460 kpc,
i.e. it is not a giant radio halo.
The radio halo seems to blend with the emission of the western relic
W--R, however it is difficult to say whether this is a true feature, since
projection effects are likely to play a role. Given the different
polarisation properties of radio halos and relics, polarisation information
would be necessary to investigate this issue.
We measured a flux density of S$_{\rm 610~MHz} = 10.3 \pm 0.3$ mJy for the
radio halo. No spectral index estimate between 610 MHz and 1.4 GHz can be
derived, due to the lack of a flux density value
at 1.4 GHz (Feretti et al. \cite{feretti05}).
\\
\\

\subsubsection{RXCJ\,2003.5--2323}\label{sec:rxcj2003}

\begin{figure*}
\centering
\hspace{-1truecm}\includegraphics[angle=0,width=8.1cm, height=6.6cm]{fig6a.ps}
\hspace{1truecm}\includegraphics[angle=0,width=8cm, height=6.7cm]{fig6b.ps}
\caption{Left -- Full resolution GMRT 610 MHz contours of the
central region of RXCJ\,2003.5--2323, superposed to the POSS--2
optical image. The resolution of the radio image is
$6.9^{\prime\prime} \times 5.0^{\prime\prime}$, p.a. $-0.3^{\circ}$,
the 1$\sigma$ level is 40 $\mu$Jy b$^{-1}$. Contours are
0.12$\times(\pm$1,2,4,8...) mJy b$^{-1}$.
Individual sources are labelled from A to H.
Right -- GMRT 610 MHz gray scale and radio contours of the
giant radio halo in RXCJ\,2003.5--2323 after subtraction of the
individual sources (from B to H in the left panel). The
HPWB is $32.0^{\prime\prime} \times 23.0^{\prime\prime}$, p.a.
$15^{\circ}$. Contours are 0.3$\times(\pm$1,2,4,8...) mJy b$^{-1}$.
The 1$\sigma$ level in the image is 100 $\mu$Jy b$^{-1}$.}
\label{fig:rxcj2003_halo}
\end{figure*}

RXCJ2003.5--2323 is the most distant cluster in our
sample, with z=0.3171 (1$^{\prime\prime}$=4.626 kpc).
Little information is available in the literature.
The ROSAT All Sky Survey (RASS) image shows that the X--ray emission
is elongated along the NW--SE direction, which
might suggest a disturbed dynamical status for RXCJ\,2003.5--2323.
\\
Our GMRT 610 MHz observations show that it is the most striking
cluster among those observed thus far.
It hosts a {\it giant} radio halo, one of the largest known up to date.
Its largest angular size is $\sim 5^{\prime}$, corresponding to $\sim$
1.4 Mpc.
Hints of the presence of this very extended radio halo were clear
already from inspection of the NRAO VLA Sky Survey (NVSS).
\\
The cluster radio emission within the cluster virial radius
is given in  Fig. \ref{fig:rxcj2003}. The central part of the cluster is
shown in Fig. \ref{fig:rxcj2003_halo}.
The left panel shows a full resolution image
superposed to the POSS--2 optical image, to highlight the individual sources
(labelled from A to H). The sources with a clear optical counterpart (B to H) were
subtracted from the u--v data when producing the image shown in the right panel
of Fig. \ref{fig:rxcj2003_halo}, which we convolved with a larger beam
in order to highlight the low surface brightness emission. We did not subtract
A, since no optical counterpart is visible on the POSS--2, therefore we
consider this feature as a peak in the radio halo emission.
One of the most striking features of this giant radio halo
is its complex morphology:
clumps and filaments are visible on angular scales of the
order of $\sim 1^{\prime}$ (clumps) and $\sim 2-3^{\prime}$ (filaments),
as clear from Figures \ref{fig:rxcj2003} and
\ref{fig:rxcj2003_halo} (right panel).
Unfortunately no deep X--ray images are available for this cluster,
therefore a combined radio and X--ray analysis cannot be carried out.
The only information we can derive from the RASS image of the cluster is
that the whole radio emission from the halo is embedded within the X--ray
emission, as shown in Fig. \ref{fig:rxcj2003_rass}.
\\
The total flux density of the radio halo (after subtraction of the point
sources) is S$_{\rm 610~MHz} = 96.9 \pm 5.0$ mJy, corresponding to
logP$_{\rm 610~MHz}$ (W/Hz) = 25.49.

\begin{figure}\label{fig:rxcj2003_rass}
\centering
\hspace{0.5truecm}\includegraphics[angle=0,width=6.5cm]{fig7.ps}
\caption{ROSAT All Sky Survey contours (black) of RXCJ\,2003.5--2323 overlaid
on the 610 MHz gray scale and contours (gray) of the radio halo.
The X--ray contours levels are logarithmically spaced by a factor of
$\sqrt 2$. The radio image is the same as right
panel of Fig. \ref{fig:rxcj2003_halo}. }
\label{fig:rxcj2003_rass}
\end{figure}

\subsection{Candidate extended emission in Abell 3444}\label{sec:minihalo}

Abell 3444 (RXCJ\,1023.8$-$2715, z=0.2542, 1$^{\prime\prime}$=3.924 kpc) was
indicated as possible cooling core cluster
by L\'emonon (\cite{lemonon99}) and Matsumoto (\cite{matsumoto01}) on the basis
of the analysis of ASCA data, though at limited significance.
The X--ray ASCA image shows that the inner part of the cluster is elongated
along the SE--NW direction.
\\
No radio information is reported in the literature. Unfortunately, due to
calibration problems, we could use only the USB of our dataset to image
this cluster. Our GMRT 610 MHz image
of the radio emission within the cluster virial radius is reported
in Fig. \ref{fig:a3444}, and shows that the radio emission is dominated by a
chain of individual sources, all with optical counterpart from the POSS--2.
The alignment of the chain of radio galaxies is in agreement with the inner
elongation of the archive ASCA X--ray image.
\\
A radio--optical overlay of the central part of the field is given
in Fig. \ref{fig:a3444_opt} (Left). The extended radio galaxy at
the north--western end of the chain is associated with the dominant
cluster galaxy (right panel in Fig. \ref{fig:a3444_opt}).
Its morphology is complex. Bent emission in the
shape of a wide angle tail is clear in the inner part of the source,
surrounded by extended emission. At least a couple of
very faint objects are visible in the same region of the extended
radio emission, so it is unclear if we are dealing with extended
emission associated with the dominant cluster galaxy, or if this
feature is the result of a blend of individual sources.
Under the assumption that all the emission detected within the
3$\sigma$ contour (left panel of Fig. \ref{fig:a3444_opt}) is associated
with the dominant cluster galaxy, we measured a flux density
S$_{\rm 610~MHz} = 16.5 \pm 0.8$ mJy,
which corresponds to logP$_{\rm 610~MHz}$(W/Hz) = 24.51. The largest
angular size of the radio source is $\sim 40^{\prime\prime}$, hence
the linear size is $\sim$ 165 kpc.
\\
Both panels of Fig. \ref{fig:a3444_opt} suggest that emission on
a larger scale may be present around the central radio source. Indeed
we measured a flux density of S$_{\rm 610~MHz} = 10.0\pm 0.8$ mJy on
an angular scale of $\sim 1.5^{\prime}$, i.e. $\sim$ 350 kpc.
\\
This situation is reminiscent of the class
of core--halo sources, where extended emission surrounds a radio
component obviously associated with a galaxy.
Core--halo sources are usually located in cooling core clusters.
Some well--known examples are 3C\,317 (Zhao, Sumi \& Burns \cite{zhao93}),
3C84 (B{\"o}hringer et al. \cite{boeringer93}), PKS 0745--191 (Baum \&
O'Dea \cite{baum91}).
\begin{figure*}
\centering
\hspace{-0.5truecm}\includegraphics[angle=0,width=9.8cm,height=7.5cm]{fig8a.ps}
\hspace{1truecm}\includegraphics[angle=0,width=7.6cm]{fig8b.ps}
\caption{Left -- GMRT 610 MHz radio contours for the cluster A\,3444
superposed on the POSS--2 optical plate.
The 1$\sigma$ level in the image is $\sim 50~\mu$Jy b$^{-1}$.
Contours are 0.15$\times(\pm$1,2,4,8,16...)  mJy b$^{-1}$ (3$\sigma$).
The HPWB is $23.2^{\prime\prime} \times 16.1^{\prime\prime}$, p.a.
$37.6^{\circ}$. Right -- High resolution zoom on the central cluster galaxy.
The HPBW is $7.6^{\prime\prime} \times 4.9^{\prime\prime}$,
p.a. $19^{\circ}$.
Contours are given starting from the 3$\sigma$ level:
0.20$\times(\pm$1,2,4,8...).}
\label{fig:a3444_opt}
\end{figure*}

\subsection{Galaxy clusters without extended emission}\label{sec:noext}

For the remaining six clusters our 610 MHz GMRT observations did
not show any indication of possible extended emission at the noise
level of the final images.

\subsubsection{S\,780}

S\,780 (RXCJ\,1459.4--1811, z=0.2357, 1$^{\prime\prime}$=3.952 kpc) is
the most X--ray luminous and most massive cluster
among those presented in this paper.
No information is available in the literature.
Inspection of the ROSAT archive indicates that the X--ray emission
is elongated in the E--W direction.
\\
Fig. \ref{fig:s0780} reports the 610 MHz contours of the S\,780 field
within the virial radius.
The radio emission from S\,780 is typical of a very active cluster,
with a number of cluster--type radio galaxies.
Beyond the dominant central radio source, one head--tail radio
galaxy is clearly visible close to the cluster centre, one wide--angle tail
is located at $\sim~6^{\prime}$ from the cluster centre (well within
the virial radius) and one FRII radio galaxy (Fanaroff \& Riley \cite{fr74})
with distorted jets is located at  $\sim~8^{\prime}$ from the cluster centre
(in the S--E direction). A few more radio
sources in the cluster field are optically identified.
A visual inspection of the optical counterparts of all these radio sources
suggests they have similar optical magnitudes.
\\
Radio--optical overlays are given in Fig. \ref{fig:s0780_opt}. The
left panel shows the central part of the cluster superposed on the
POSS--2 optical frame, and the right panel is a high resolution zoom of
the central cluster galaxy. The radio galaxy shows a compact component
coincident with the nucleus of the associated galaxy, extended emission
in the eastern direction and a filament aligned South--East.
The total angular size is $\sim 50^{\prime\prime}$, corresponding to
a largest linear size LLS $\sim$ 200 kpc. The flux density is
S$_{\rm 610~MHz} = 135.9 \pm 6.8$ mJy, i.e.
logP$_{\rm 610~MHz}$(W/Hz) = 25.32. Sources A and B highlighted in the right
panel of  Fig. \ref{fig:s0780_opt} were not included in the flux density
measurement. The flux density of the filament just South of the central
radio source is S$_{\rm 610~MHz} = 3.1 \pm 0.2 mJy$.
No indication of residual flux density is present in the cluster centre.
\\
\\
\begin{figure*}
\centering
\hspace{-0.5truecm}\includegraphics[angle=0,width=9.0cm,height=7.8cm]{fig9a.ps}
\hspace{1truecm}\includegraphics[angle=0,width=8.3cm]{fig9b.ps}
\caption{Left -- GMRT 610 MHz radio contours for the cluster S\,0780
superposed on the POSS--2 optical plate.
The 1$\sigma$ level in the image is 65$~\mu$Jy b$^{-1}$.
Contours are 0.20$\times(\pm$1,2,4,8,16...)  mJy b$^{-1}$.
The HPWB is $20.9^{\prime\prime} \times 15.9^{\prime\prime}$, p.a.
$45.9^{\circ}$. Right -- High resolution zoom on the central cluster
galaxy. The HPWB is $7.5^{\prime\prime} \times 5.0^{\prime\prime}$, p.a.
$25^{\circ}$. Contours are 0.19$\times(\pm$1,2,4,8,16...)
mJy b$^{-1}$ (first contous is 3$\sigma$).}
\label{fig:s0780_opt}
\end{figure*}

\subsubsection{Abell 2697}
Very little information is available in the literature for
A\,2697 (RXCJ\,0003.1--0605, z=0.2320, 1$^{\prime\prime}$=3.698 kpc).
Archive X--ray ROSAT and ASCA images show that the hot intracluster
gas has a fairly regular distribution.
\\
For this cluster only one portion of the band (USB) was available. We
imaged the cluster in a range of resolutions,
reaching a 1$\sigma$ noise level of
$\sim 80~\mu$Jy b$^{-1}$ in each image.
The radio field is dominated by a head--tail galaxy.
Radio contours are reported in Fig. \ref{fig:a2697} in the Appendix.
\\
No cluster--type extended feature is visible at the sensitivity
level of the images, and no significant flux density from positive
residuals was found by integrating over a wide region of the
cluster centre.
\\

\subsubsection{Abell 141}

The X--ray emission of A\,141 (RXCJ\,0105.5--2439, z=0.2300,
1$^{\prime\prime}$=3.674 kpc) is bimodal. The archive X--ray ROSAT
images show that the North--South elongation of the ASCA image is the
result of two components, the northern one being the brightest and
largest. The same orientation was found also in the
distribution of the cluster galaxies by Dahle et al. (2002), who concluded
that the overall optical analysis is suggestive of recent
merger activity. Those authors reported also evidence of weak lensing.
\\
High resolution radio imaging aimed at the detection of cluster radio
galaxies was carried out with the VLA--A at 1.4 GHz by Rizza et al.
(\cite{rizza03}).
\\
For this cluster only one portion of the observing band (USB) was
available.
Our GMRT observations of A\,141 revealed neither the presence of diffuse
emission at the level of $\sim 100~\mu$Jy b$^{-1}$, nor unusually high residuals.
Radio contours are reported in Fig. \ref{fig:a141} in the Appendix.

\subsubsection{Abell 3088}

Very little information is available in the literature for
A3088 (RXCJ\,0307.0$-$2840, z=0.2537, 1$^{\prime\prime}$=3.952 kpc).
It is a richness 2 galaxy cluster with a
very regular and symmetric X--ray morphology. On the basis of XMM--Newton
observations, Zhang et al. (\cite{zhang06}) reported a gas temperature
kT=6.4$\pm$0.3 keV and classified it as a ``single dynamical state'' cluster
with a cooling core (Finoguenov, B{\"o}hringer \& Zhang \cite{finogue05}).
\\
Our GMRT 610 MHz observations show that the field has only a few radio sources,
with a lack of positive residual flux density in the central cluster region
and no hints  of diffuse emission from the cluster at the detection level
of our images, i.e  1$\sigma~\sim~65~\mu$Jy b$^{-1}$.
Contours of the radio emission within the cluster virial radius
are shown in Fig. \ref{fig:a3088}.

\subsubsection{Abell 2537}

Little information is available in the literature for
A\,2537 (RXCJ\,2308.2--0211, z=0.2966, 1$^{\prime\prime}$=4.419 kpc).
Archive HST observations show the presence of several red and blue arcs,
and Dahle et al. (\cite{dahle02}) report evidence of weak lensing.
The cluster was observed in the X--ray band by XMM--Newton
and was classified as ``single dynamical state'', with gas temperature
kT=7.9$\pm$0.7 KeV (Zhang et al. \cite{zhang06}).
A secondary X--ray peak is present at $\sim~7^{\prime}$ from the
cluster gas concentration.
\\
For this cluster only the USB provided useful data.
The 610 MHz radio emission from the cluster, shown in Fig. \ref{fig:a2537}
is dominated by a tailed radio galaxy located at the cluster centre.
Very few other radio sources are detected above the 5$\sigma$ level of
the image. No hint of extended emission is present in the field
at the level of $\sim 60~ \mu$Jy b$^{-1}$ (1$\sigma$), and no
high positive flux density residuals were detected over the central
cluster region.
\\

\subsubsection{Abell 2631}

Little information is available in the literature for the rich cluster
A\,2631 (RXCJ\,2337.6+0016, R=3, z=0.2779, 1$^{\prime\prime}$=4.221 kpc).
Archive ROSAT X--ray images are available for A\,2631, which show a
complex morpholgy. Based on XMM--Newton observations Zhang et al.
(\cite{zhang06}) classified it as ``offset centre'', with varying
isophote centroids on different angular scales, and reported
a gas temperature kT=9.6$\pm$0.3 KeV. Finoguenov et al. (\cite{finogue05})
interpret the XMM properties of this cluster in terms of a late stage
of a core disruption.
The cluster was observed with the VLA--A at 1.4 GHz
(Rizza et al. \cite{rizza03}).
\\
Our GMRT observations of this cluster were spread over two days,
however on both days only one portion of the band (USB) was available.
The 610 MHz radio emission of A\,2631 within the virial radius is
shown in Fig. \ref{fig:a2631}. It is dominated by a central
tailed radio galaxy and all the remaining sources above the 5$\sigma$
level are located South of the cluster centre. No signs of extended emission
are present in the field at the rms level of $\sim 50~ \mu$Jy b$^{-1}$
(1$\sigma$), and no positive residuals were found by integrating over the
central region of the cluster.
\\

\section{Discussion and conclusions}\label{sec:discussion}

Our 610 MHz GMRT radio halo survey has been designed in
order to statistically investigate the connection
between cluster merger phenomena and the presence of cluster--scale
radio emission. In particular, our main goal is to derive the fraction
of massive clusters (i.e. $M \ge 10^{15} M_{\odot}$) with
giant radio halos in the redshift range 0.2$<$z$<$0.4, in order to constrain
the expectations made by CBS04 and CB05 in the framework of the
particle re--acceleration model.
The total cluster sample consists of two sub--samples of massive clusters
extracted from the REFLEX and extended BCS catalogues, and includes a total
of 50 clusters.
\\
The cluster sample presented here (see Table 1) includes 27 REFLEX
clusters, eleven of which were observed in a first run of GMRT observations
carried out in January 2005. If we consider the literature data, information
is now available for 15 of the 27 objects.
The most relevant results we obtained, as well as the status of the observations for
the remaining clusters in the sample are summarized below.

\begin{itemize}

\item[{\it (a)}] Two new giant radio halos were found,
i.e. A\,209 (also reported in Giovannini et al. \cite{gg06} while
this paper was in preparation), and RXCJ\,2003.5--2323, discovered with the
present 610 MHz GMRT observations.

\item[{\it (b)}] A radio halo (LLS$\sim$460 kpc) was found in
RXCJ\,1314.4--2515.

\item[{\it (c)}] Two relics were found in the cluster RXCJ\,1314.4--2515,
and one  in A\,521 (Giacintucci et al. \cite{giacintucci06}).
These three relics are impressive structures.
Their largest linear size is of the order of the Mpc, which suggests
that particle acceleration, most likely related to the hierarchical
formation of clusters and accretion processes, might be required to
account for their formation (e.g. Ensslin \& Br\"uggen \cite{eb02}).
The relic in A\,521 has already been
studied in detail. Here we just wish to mention that RXCJ\,1314.4--2515
is the third galaxy cluster known to date hosting two relics,
after A\,3667 (Roettiger, Burns \& Stone \cite{roetti99};
Johnston--Hollitt et al. \cite{jh02}) and A\,3376 (Bagchi et al. \cite{bagchi06}).
Furthermore, it is unique in hosting two relic sources and one radio halo,
and hence a challenge for our understanding of the connection between radio
halos, relics and the physics of cluster mergers.

\item[{\it (d)}] Extended emission on smaller scale (of the order of $\sim 350$ kpc)
was detected around the dominant galaxy
in A\,3444, whose radio morphology and monocromatic power are similar to those
of core--halo radio galaxies found at the centre of cooling core clusters.

\item[{\it (e)}] Three clusters in the sample host  well--known giant
radio halos, i.e. A2744 (Govoni et al. \cite{govoni01}), A1300
(Reid et al. \cite{reid99}) and A2163 (Herbig \& Birkinshaw \cite{herbig94},
Feretti et al. \cite{feretti01}).

\item[{\it (f)}] No extended emission of any kind was detected at the level
of 50 -- 100 $\mu$Jy b$^{-1}$ in six of the 11 clusters observed by us and
presented here.

\item[{\it (g)}] The cluster RXCJ\,0437.1+0043 is known not to host extended emission,
based on low resolution 1.4 GHz VLA observations (Feretti et al.
\cite{feretti05}).

\item[{\it (h)}] Five clusters were observed by us in October 2005, two more will be
observed in August 2006, and they will be presented in a future paper
(see Sect. \ref{sec:obs}).

\item[{\it (h)}] The remaining 5 clusters are being observed by other authors
(GMRT Cluster Key Project, P.I. Kulkarni) and no literature information
is available thus far.

\end{itemize}

\begin{figure}
\centering
\includegraphics[angle=0,width=8.5cm]{fig10.ps}
\caption{LogL$_{\rm X}$--LogP$_{\rm 1.4~GHz}$ plot for the clusters
with detected giant radio halos. Stars represent the literature clusters
at z$<$0.2 and filled circles the literature clusters at z$>0.2$.
Open circles show the location of A\,209 (lower left)
and RXCJ\,2003.5--2323 (upper right).}
\label{fig:LxLr}
\end{figure}

In Fig. \ref{fig:LxLr}
we show the location of the giant radio halos in A\,209 and
RXCJ\,2003.5--2323 in the log~L$_{\rm X}$ -- log(P$_{\rm 1.4~GHz}$) plane,
where all the previously known clusters with giant radio halos are also
reported (see CBS06 and references therein for the literature data).
The radio power at
1.4 GHz for these two clusters was obtained scaling the measured flux density
at 610 MHz with a spectral index $\alpha_{\rm 610~MHz}^{\rm 1.4~GHz} =
1.2 \pm 0.2$ (the uncertainty assumed here dominates over the 610 MHz
flux density error). Clusters at z$<$0.2 and those at z$>$0.2 are shown with
different symbols. Despite some overlap, the most powerful radio halos are
hosted in the most X--ray luminous clusters, which are also the most distant.
The location of A\,209 and RXCJ2003.5--2323 on the plot is in good agreement
with the distribution of all giant radio halos known in the literature.
\\
\\
An important piece of information would be the knowledge of the
merging stage of the clusters in the sample, since cluster merger is a major
ingredient in the re--acceleration model.
The literature information on the clusters presented here is not
homogenous, and it is not possible to make conclusive statements
on the connection between merging/non--merging signatures and the
presence/absence of radio halos. A\,209 is known to be undergoing merging
events, but no information is available for RXCJ\,2003.5--2323, except
for the elongated X--ray emission imaged by ROSAT. The three
radio halo clusters known from the literature are all reported to
be dynamically active
(see for instance Zhang et al. \cite{zhang06} and Finoguenov et
al. \cite{finogue05}). Signature
of cluster merger is present in the optical and X--ray bands
for A\,521 (Giacintucci et al. \cite{giacintucci06} and references therein)
and RXCJ\,1314.4--2515, which host extended radio
emission in the form of radio halo and relics. Elongated or more
complex X--ray isophotes are visible in S\,780, A\,141, A\,2631
and in RXCJ\,0437.1+0043, which lack cluster scale
radio emission.
The remaining two clusters without extended emission are considered
``relaxed'' on the basis of the X--ray emission
\\
To summarize, the optical and X--ray information for the sample of
clusters presented here is not inconsistent with the findings that clusters
with radio halos are characterised by signatures of merging processes.
On the other hand, clusters without extended radio emission may or may not
show dynamical activity at some level.
This crucial issue will be further investigated in future works.
\\
\\
In the framework of the canonical particle re--acceleration model
giant radio halos are believed to be essentially
an on/off phenomenon, triggered by dissipation via collisionless
damping of turbulence injected during cluster mergers.
\\
The physics of collisionless turbulence and of particle acceleration is
still poorly understood and many hidden ingredients could be of relevance
in computing the efficiency of the particle acceleration processes
in the ICM.
On the other hand, from simple energetic arguments,
it is clear that the possibility to develop a giant radio halo
is related to the efficiency of turbulence injection and to the
possibility to generate large enough ($\geq$Mpc sized) turbulent cluster
regions. In this respect, the calculations in CBS04, CB05 and more recently
in CBS06 show that major cluster mergers (i.e. with  mass ratio of the
order $\leq$ 5:1) between massive clusters (M$\geq 10^{15}$M$_{\odot}$) may
provide the necessary ingredients to develop giant radio halos.
During these mergers a fraction of up to $\sim 10\%$ of the cluster
thermal energy is believed to be injected in a $\sim {\rm Mpc}^3$ region.
However, from a theoretical point of view, it is hard to predict if a
particular merging
clusters may host a giant radio halo, since this depends
on a number of parameters which cannot be easily estimated.
For instance, in order to have enough time for the turbulence injected
on large scales to cascade down to collisionless scales, it is necessary
that seed relativistic particles (to be reaccelerated) are present
in the turbulent ICM, and that the magnetic field in the ICM is strong
enough to allow $\sim$GeV electrons to emit synchrotron radiation at the
observed frequency.
\\
The statistical approach developed in CBS04, CB05 and CBS06 allows
a more reliable estimate of the fraction of clusters hosting a giant
radio halo.
Without going into the calculation details, the most
relevant result in the light of those papers is that the
fraction of galaxy clusters with mass
$\sim 2-3.5\times 10^{15} M_{\odot}$ and redshift $z = 0.2 \div 0.4$
expected to host a giant radio halo is in the range
$\sim 10-35 \%$.
In addition, CBS06 showed that the cluster magnetic field plays
an important role, and that this fraction depends
the scaling law between the magnetic field and cluster mass.
\\
Radio information is now available for 15 of the 27
clusters considered in this paper, and 5 of them possess a giant radio
halo. However, at this stage of our work the statistics are still poor,
and no firm comparison with theoretical expectations can be reached.
For this reason our analysis, in the light of
the predictions made in CB05 and CBS06, will be carried out as soon
as the information on the whole selected sample (REFLEX and BCS) is
completed (Venturi et al. in prep.; Cassano et al in prep.).
\\
\\
{\it Acknowledgements.}
We thank the staff of the GMRT for their help during the observations.
GMRT is run by the National Centre for
Radio Astrophysics of the Tata Institute of Fundamental Research.
T.V. and S.G. acknowledge partial support from the Italian Ministry
of Foreign Affairs. G.B., R.C. and G.S. acknowledge partial support
from MIUR grants PRIN2004 and PRIN2005.

redpajama_set_name: RedPajamaArXiv


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The caregiver must possess a valid driver's license, though a car is not required.Pay for this part time job is negotiable based upon experience, with a starting rate of $13.50/hr.


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link to How To Remove Duct Tape Residue (8 Ways To Do It!)
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link to Goo Gone vs. Goo Off: What Are The Major Differences?
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Sliding glass doors were once a staple in homes across the country. But that time was the 1970s and 1980s and those days are long gone. With today's' homes, those sliding glass doors can look quite...
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During the process of improving or renovating a room, it may prove to be beneficial if you remove the baseboards. It is important to note that you should reserve this for when there is chipping or...
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How To Remove A Dishwasher With A Raised Floor (The Best Way!)
When you come to the point that you need a new dishwasher, there is the question of removing the old one. Pulling out the existing dishwasher is generally a pretty easy job unless the floor...
Ryan Womeldorf has more than a decade of experience writing. He loves to blog about construction, plumbing, and other home topics. Ryan also loves hockey and a lifelong Buffalo sports fan.
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Today I had the great pleasure of speaking at The Innovation Enterprises' 2013 Women in Strategy Summit, which brings together 75 high-level women in marketing and strategy, about the leadership secrets of the world's most powerful women. With women comprising just 4% of corporate CEOs, 14% of executive officers and 20% of America's government officials, we're facing a persistent leadership gap at the highest echelons. To move forward, we must first take stock of what is working. The following eight leadership lessons, synthesized and updated from a keynote I gave last year, come directly from the women who know what it takes to get to the top.
The world's most successful women really want it–and remain determined even in the face of obstacles. They have the skills, and they put the time in. But more importantly, they have the desire to do something great. Beth Brooke, global vice chair of Ernst & Young, was diagnosed with a degenerative hip disease at age 13 and was told by doctors she may never walk again. Before going into surgery she promised herself she would walk—no, she would run—and aspired to become one of the best young athletes the world had seen. Not only did she walk, she went on to play several varsity sports at her high school, earned multiple MVP awards, and later played Division I basketball in college. She made up her mind, and she didn't quit. She brought that same determination to her career and today ranks among the 100 most powerful women in the world.
Women at the top aren't fearless. They move toward their fear to continually challenge themselves. That takes courage. In 2011, Beth Mooney, CEO of KeyCorp, became the first woman ever to lead a top-20 bank in the U.S. Mooney began her career as a secretary at a local Texas bank, making just $10,000 a year, but soon realized she wanted something more. In 1979, she knocked on the door of every big bank in Dallas and asked for a spot in their management training programs. At the Republic Bank of Dallas, she refused to leave the manager's office until he offered her a job. After waiting for three hours, he finally agreed to give her a chance if she earned an MBA by night.
That was a turning point in her career, one of many, powered by a courageous call to action—to champion herself and what she knew she was capable of. Later, she had the courage to move into roles she'd never done before, to pick up and move across the country, and to stick with it for three decades. If you're not a little bit scared every day, you're not learning. And when you're not learning, you're done.
In order to achieve big success, you have to have big impact. When Michelle Gass, who is now leading 33 countries for Starbucks, started at the coffee chain, she was asked to architect a growth strategy for a just-launched drink called the Frappuccino. Her mantra: "Let's think of how big this can be." After countless hours testing ideas, she decided to position it as an escapist treat and added ice cream parlor fixings and new flavors. What began as a two-flavor side item is now a $2 billion platform with tens of thousands of possible combinations. Gass repeated her go-big-or-go-home strategy when she took over Seattle's Best Coffee. She decided to take the sleepy little-sister brand to new heights by partnering with Burger King, Delta, Subway, convenience stores and supermarkets. In one year, the brand exploded from 3,000 distribution points to over 50,000.
As CEO of Kraft Foods and now Mondelez International, Irene Rosenfeld is very familiar with this one. A couple years ago she completed a hostile takeover of British candy company Cadbury. Not long after, she surprised the business community again with a plan to split Kraft into two separate companies, a North American foods company and a global snacks company. To move the needle, you have to make a big bets—but never rash—always based on a careful study of the outcomes. You have to know what you have to gain, and if you can afford to take the hit if it doesn't go your way.
It takes discipline to achieve and maintain success. You simply can't do everything, and the world's most powerful women stay focused on the areas that will have the biggest impact—from both a leadership perspective and a career management perspective. Sheri McCoy, the new CEO of struggling Avon Products, is currently implementing a huge turnaround at the century-old beauty company. Interestingly, when I asked what the biggest challenge would be, she said: "Making sure people stay focused on what's important and what matters most." It is very easy to get distracted by new trends, new markets, new projects—but when you extend yourself too far, the quality of your work suffers across the board.
Over and over again women at the top say their best strategy for success is to hire people who are diverse, passionate and smarter than themselves–and then listen closely to their perspectives. Hala Moddelmog, president of Arby's Restaurant Group, believes surrounding yourself with people of different backgrounds—including gender, race, geography, socio-economic and personality types—will help round out your conclusions. "You really don't need another you," she says. Similarly, staying open to different viewpoints keeps you ahead of the curve. Claire Watts, the CEO of retail and media company QVC, schedules open door times every Tuesday, so that anyone in the company who wants to come talk to her, ask her a question or share something they've noticed can do it then.
Denise Morrison, the CEO of Campbell's Soup, knew from a very young age she wanted to eventually run a company, so she asked herself what are the kinds of things I need to do to prepare for that? That might mean management experience, global exposure or revenue responsibility. She always looked at her career as: Where have I been? Where am I now? Where am I going, and what are the right assignments to get there? If her current company would work with her to deliver those assignments, she was all-in. But if it didn't, she knew she needed to move on. "We apply these skills in business, and yet when it comes to ourselves we rarely apply them," she said.


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Cooling Tower Ozone Sterilization
Home / Industrial Ozone Applications / Cooling Tower Ozone Sterilization
Cooling towers use water as a circulating coolant, which absorbs heat from a system and releases it into the atmosphere to have the system cooled. The cooling water in a cooling tower will be recycled through the system. However, the circulating cooling water provides suitable temperature and humidity conditions for the growth of bacteria and microorganisms. And microbial growth can lead to problems such as sediment attachment, equipment corrosion, and algae blooms. This will lead to blockages in pipes and, more troubling, to bacteria such as Legionella, which can cause serious health concerns. The good news is that cooling tower ozone sterilization is now the best solution for the problem.
For the treatment of circulating water in cooling towers, chlorine preparations or organic biocides at low costs were generally applied in the past. These solutions may have great impacts on the environment. Chlorine agents and organic biocides cannot effectively inhibit resistant bacteria but will add toxins and make the water more corrosive. In the face of this problem, in recent years, as a better solution, cooling tower ozone sterilization has gradually been widely recognized and adopted.
How Does Ozone Work?
The use of ozone in cooling towers was encouraged by the gradual limitation of chlorine sterilization of circulating water in the late 1970s when the U.S. Environmental Protection Agency (EPA) found that chlorination of water produced a variety of carcinogenic organics. As a strong oxidant, ozone has many advantages. Ozone has a strong sterilization ability, which is also simple in practical operation. Ozone treatment does not change the pH value of the water or cause any secondary pollution. The application of ozone in cooling water treatment is mainly shown in the following aspects:
1. Ozone can prevent the formation of scales
The scale in the circulating water of a cooling tower is formed from the concentration and crystallization of salt substances in the water. By introducing ozone into the water, the cooling water can be guaranteed to be free of scale at a total dissolved solids of 1600mg/L and a hardness of 710mg/L. This is impossible for those ordinary scale inhibitors. According to an analysis, the significant effect of ozone is due to its ability to move carbonates towards bicarbonates. Therefore, the ozone sterilization of cooling tower has a significant advantage over other scale inhibitors.
2. Ozone can prevent the corrosion of metals
Ozone, as a strong oxidant, was once considered corrosive. However, recent studies have shown that ozone has a very good prevention of metal corrosion. This is because the oxygen atoms generated after ozone decomposition can react with ferrous ions. The reaction will form a passivation film on the surface of the positive electrode, thus playing a good role in protecting the metal from corrosion. Tests have shown that ozone can reduce the corrosion rate of steel by 1/3 to 1/2.
3. Ozone's killing effect on bacteria, viruses and microorganisms
Ozone is a recognized pollution-free biocide. Ozone at 0.1 PPM can effectively kill bacteria and viruses, and control the growth of microorganisms in circulating water in cooling towers. Ozone also oxidizes the organic composition of the dirt that has formed, making the dirt loose and easy to be removed. Cooling tower ozone sterilization can effectively control the growth of microorganisms and also reduce the difficulty of daily cleaning and maintenance of cooling towers.
According to statistics, cooling tower ozone sterilization can reduce about 50% of the sewage discharge and slow down the corrosion rate of metal also at about 50%. By ozone descaling, the equipment can save energy up to about 15% and the compressor performance can be improved by over 5%. From an economic point of view, using ozone can reduce costs by more than 50% compared to using traditional water treatment methods.
Operation Method for Cooling Tower Ozone Sterilization
The method of applying ozone in the circulating water of a cooling tower is not complicated. It can be done by introducing the ozone generated by an ozone generator into the water to be treated. The concentration of ozone can be monitored and controlled with the help from a manual ozone test kit or meter.
In our previous Blog posts, we talked about the significant role of ozone in removing kitchen odors, car odor, smoke smell, and many other kinds of odors. We have also discussed the advantages of ozone in water treatment industry, its use in aquariums, swimming pools, and in the production of bottled water. You can read them by checking out our Blog. As a gas with strong oxidizing ability, the field in which ozone can function is impossible to define. Its application scope will continue to expand with the development of the present industries, the advancement of technology and the emergence of new industries.
Hi, what is the price of the Cooling Tower Ozone Sterilization? Can I get any details about it? Please reply me soon! Regards!


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Created by Rob Liefeld and Fabian Nicieza, antihero Deadpool, aka Wade Wilson, has appeared in comic books from Marvel since February 1991's The New Mutants #98… and the world has never been the same! Known for his insouciant, talkative manner, the smart-alecky "Merc with a Mouth" is the inspiration for Deadpool action figures and gobs of other fan-demanded items.
Originally a supervillain, the trained assassin and mercenary evolved over time into the current more well-known antihero. In addition to comic books, he's been seen in animated and live-action films, television, and web series, and in video games. Therefore, there are many a Deadpool statue, plush, and other collectible article for his many fans to covet.
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