Bimah-Sinkhole -Oman

This strange wonder is found on Oman’s east coast approximately 1 hour and 45 minutes from Muscat. It’s basically a huge hole/cave like structure filled with water from the close by ocean. The water is azure blue and there are plenty of places to climb up the rocks and jump into the clear water. It is commonly called the Sink Hole and got its name from its sink-like shape, filled with water. The water has a very high salt level caused by evaporation. 

Orinduik waterfall

Orinduik waterfall has formed on sturdy rocks of pure, red jasper - a beautiful ornamental stone. This is not unique - rather many waterfalls in this part of South America have formed on this stone.
The true size of falls can be appreciated from the air. River has many steps before and after the falls. Falls themselves have three major steps and numerous smaller ones. Steps have complex configuration, with an island in the middle.
Name of waterfall originates from a local Carib (possibly - Patamona) name ("orin" or similar word) - which in turn is a name to a plant which grows in the rocks in the stream.

Kaieteur Falls

This is Kaieteur Falls,
Which is about three times higher than the more well known Niagara Falls and about two times the height of the Victoria

Falls.

Kaieteur is located in the central part of Guyana Highlands, consisting of several billion years old rocks. This part of Guyana Highlands contains higher ridge named - Pakaraima Mountains, consisting of plateaus with steep sides.
Guyana is rich with waterfalls but this region is superior in this respect. Numerous powerful rivers fall here over the edges of plateaus.

Radiation Dosage and Decay

There are several methods to measure radiation; hence, there are several radiation units based on different radiation factors. Radiation units can measure radioactive decay, absorbed dosage, and human absorbed doses. Bq and Ci measure radioactive decay, while Gy and Rad measures absorbed doses. Sv and Rem measure absorbed doses in Gy and Rad equivalents. Rem takes into account different radiation types and the speed of particles. Below is a chart to help organize the different units:

Units for Radioactive Decay

Becquerel, Bq	Measured in s-1, as disintegration per second
Curie, Ci	Measured as amount of decay at the same rate as 1 gram of radium 1 Ci = 3.70∙1010 Bq

Units for Absorbed Dose

Gray, Gy	1 Gy deposits 1 Joule of energy per kilogram of matter
Rad	1 rad = 0.01 Gy

Equivalent Doses

Sievert, Sv	1Sv= 100 rem
Rem	1 rem = 1 rad∙Q Q = 1 for X-rays, gamma rays, and beta particles Q = 3 for slow neutrons Q = 10 for protons and fast neutrons Q = 20 for alpha particles

The most commonly used unit is the "rad," which stands for "radiation absorbed dose," and the "rem," which stands for "radiation equivalent for man." One rad corresponds to the absorption of 0.01 Joules of energy per kilogram of matter. Rem is the rad multiplied by the relative biological effectiveness, which is most often expressed as the variable "Q." The factor Q is used to take into account the different effects caused by different radiation.

Radiation and DNA

Radiation is simply a mechanism whereby energy passes through space. It takes the form of an electromagnetic wave, with the frequency of the electromagnetic wave determining its position in the electromagnetic spectrum. Low-frequency waves such as radio waves lie at one end of the spectrum and high-energy, high-frequency X-rays/Gamma rays at the other end. These high-frequency, high-energy waves are termed “ionizing” (as opposed to non-ionizing) radiation because they contain sufficient energy to displace an electron from its orbit around a nucleus. The most important consequence of this displaced electron on human tissue is the potential damage it can inflict on DNA, which may occur directly or indirectly. Direct damage occurs when the displaced electron hits and breaks a DNA strand. Indirect damage occurs when the electron reacts with a water molecule, creating a powerful hydroxyl radical which then damages the cell’s DNA.
Damage to a cell’s DNA in either of these ways can have several consequences. A single-strand DNA break is usually repaired appropriately by the cell with no subsequent deleterious sequelae. However, a break affecting both strands of DNA allows the potential for abnormal reconnection of the strands, which likely accounts for all the adverse biological effects ionizing radiation has on humans. First, DNA may rejoin itself incorrectly, rendering the cell nonviable with cell death taking place. Second, it may rejoin as a symmetrical translocation with the potential expression of an oncogene during division (and development of subsequent malignancy) or with abnormal division in gonads, giving rise to potential hereditary disorders.
Radiosensitivity is the probability of a cell, tissue, or organ suffering an effect per unit dose of radiation. Radiosensitivity is highest in cells which are highly mitotic or undifferentiated. For this reason the basal epidermis, bone marrow, thymus, gonads, and lens cells are highly radiosensitive. Muscle, bones, and nervous system tissues have a relative low radiosensitivity.

Aren't children more sensitive to radiation than adults?

Yes, because children are growing more rapidly, there are more cells dividing and a greater opportunity for radiation to disrupt the process. EPA's radiation protection standards take into account the differences in the sensitivity due to age and gender.

Fetuses are also highly sensitive to radiation. The resulting effects depend on which systems are developing at the time of exposure.

Prenatal Radiation Exposure

Rapidly proliferating and differentiating tissues are most sensitive to radiation damage. Consequently, radiation exposure can produce developmental problems, particularly in the developing brain, when an embryo/fetus is exposed prenatally.

The developmental conditions most commonly associated with prenatal radiation exposure include low birth weight, microcephaly, mental retardation, and other neurological problems. These effects are related to the developmental stage at which the exposure occurs. The threshold dose for developmental effects is approximately 10 rems.

The evidence that the developing embryo/fetus is more sensitive to radiation-induced cancer is inconclusive. But it is prudent to assume that there is some increased sensitivity.