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thelandofmaps:

Size of Ohio River watershed shown by its many tributaries [823x823]CLICK HERE FOR MORE MAPS!thelandofmaps.tumblr.com

thelandofmaps:

Size of Ohio River watershed shown by its many tributaries [823x823]
CLICK HERE FOR MORE MAPS!
thelandofmaps.tumblr.com

3 days ago  0:00    69 NOTES    via   source    reblog

“Romantically, you could say that we are all made of stardust, but the truth is also, that we’re all just nuclear waste.”

Professor Jim Al-Khalili

1 week ago  22:49    2059 NOTES    via   source    reblog

we-are-star-stuff:

What Are Conjoined Twins?

Twins whose bodies are connected are called conjoined twins.

Births of conjoined twins, whose skin and internal organs are fused together, are rare. Conjoined twins occur once every 200,000 live births, and their survival is anything but assured.

For some reason, female siblings seem to have a better shot at survival than their male counterparts. Although more male twins conjoin in the womb than female twins, females are three times as likely as males to be born alive. Approximately 70 percent of all conjoined twins are girls.

Conjoined twins begin as a single fertilized egg. Usually a single fertilized egg develops into a single baby. Sometimes a single egg divides in half during the first one to two weeks after it’s fertilized. This creates a set of identical twins.

The exact cause of conjoined twinning is not known. There are two theories. One is that the egg divides late and does not divide completely. The other is that the egg divides completely but then fuses (joins) back together.

The connection between the twins’ bodies may be fairly simple. They may share only a small amount of tissue, and both children may have all the organs and other structures they need. For example, the twins may be joined at the belly with a “bridge” that connects their livers.

Usually the connection is more complex, and sometimes it is very complex. The children may share:

  • Vital organs, like one heart
  • Many structures, like several parts of their digestive, genital and urinary systems
  • A large segment of their body, like all of their lower body
  • Part of the brain and skull

Types of conjoined twins

Doctors group conjoined twins based on where they are joined.

  • Joined at the chest, called thoracopagus. This is the most common type. About 40% of conjoined twins are in this group. These twins are face to face. In about 75% of cases, they share one heart. Twins joined at the chest may also share their liver, biliary tract (which carries bile from the liver to the small intestine) and upper digestive tract.
  • Joined from the breastbone to the waist, called omphalopagus or xiphopagus. These twins are face to face. They may share their liver, biliary tract and upper digestive tract. About 35% of conjoined twins are in this group.
  • Joined at the sacrum and buttock area, called pygopagus. These twins are back to back. They may share part of their lower digestive tract and parts of their skeleton, nervous system and genitals. About 20% of conjoined twins are in this group.
  • Joined in the pelvic area, possibly up to the breastbone, called ischiopagus. These twins may be oriented to each other in different ways. In general, they partly face each other. They may share their liver and biliary tract, part of their upper and all of their lower digestive tract, their genital and urinary systems and part of their skeleton. About 6% of conjoined twins are in this group.
  • Joined at the head, called craniopagus. These twins may share their skull, brain and other parts of their nervous system. About 2% of conjoined twins are in this group.

Outlook for Conjoined Twins

Most sets of conjoined twins do not survive because their organs cannot support them. About 40% of conjoined twins are not alive when they are delivered (stillborn). About 35% die within a day after they are born. The overall survival rate of conjoined twins is somewhere between 5 percent and 25%.

Survival

Even so, more conjoined twins survive now than in the past. Advances in imaging, surgical techniques and anesthesia have helped improve chances for survival. We also have tools to detect their condition before birth. This means their families and doctors can plan their early care before they are born.

Usually this includes scheduling delivery by cesarean section (C-section) a month before their due date. This is because a vaginal birth is too hard for mother and babies.

Among the conjoined twins who survive more than a day after birth, some continue to live for days, weeks, months or years while conjoined. Some live into adulthood still physically connected to each other.

Some have surgery to be separated, usually in the first year of life. The success of this surgery depends on many factors, mainly where the twins are connected and which structures they share. In some cases, both twins survive after surgery. In some cases, only one survives, or neither does.

Although success rates have improved over the years, surgical separation is still rare. Since 1950, at least one twin has survived separation about 75 percent of the time.

[Sources: x x]

1 week ago  22:48    390 NOTES    via   source    reblog
ultrafacts:

Source: 1 2 3 4 5 6 If you want more facts, follow Ultrafacts

ultrafacts:

Source: 1 2 3 4 5 6 If you want more facts, follow Ultrafacts

1 week ago  22:45    134467 NOTES    via   source    reblog
sweetdeffect:

Bluntnose stingray (Dasyatis say) with embryos.  Photo credit: NEFSC/NOAA.

sweetdeffect:

Bluntnose stingray (Dasyatis say) with embryos.
Photo credit: NEFSC/NOAA.

1 week ago  22:42    19 NOTES    via   source    reblog
malformalady:

Keratomalacia is an eye disorder that leads to a dry cornea. One of its major causes is Vitamin A deficiency. When xerophthalmia (a major cause of blindness) persists for a long time, it results in keratomalacia. Later corneal opacities develop. Bacterial infection leads to corneal ulceration, perforation of cornea, and total blindness.

malformalady:

Keratomalacia is an eye disorder that leads to a dry cornea. One of its major causes is Vitamin A deficiency. When xerophthalmia (a major cause of blindness) persists for a long time, it results in keratomalacia. Later corneal opacities develop. Bacterial infection leads to corneal ulceration, perforation of cornea, and total blindness.

1 week ago  17:01    821 NOTES    via   source    reblog

asapscience:

Paper Towels vs Hand Dryers!

When it comes to hygiene, which should you be using? We break down the efficacy of both methods in our latest video

1 week ago  16:27    140 NOTES    via   source    reblog
sweetdeffect:

Snake fetus.

sweetdeffect:

Snake fetus.

1 week ago  16:22    260 NOTES    via   source    reblog
uhohmarty:

Ice Covered Street Lamp on Mt Washington

uhohmarty:

Ice Covered Street Lamp on Mt Washington

1 week ago  16:21    46803 NOTES    via   source    reblog

1 month ago  22:07    7717 NOTES    via   source    reblog