Octreotide scan (a) demonstrates a metastatic foci of neuroendocrine tumor in the periaortic location. The lesion was treated with irreversible electroporation (b) and follow-up imaging demonstrates resolution of the focus (c).
Single metastatic focus in a lung cancer patient treated with irreversible electroporation. (a) CT scan demonstrating the metastatic focus in the liver (arrow), and placement of the five probes used to treat the lesion. (b and c) Follow-up CT scan performed 8 and 12 months posttreatment, respectively, demonstrating no evidence for recurrent disease.
Transactions don't start out as irreversible. Instead, they get a confirmation score that indicates how hard it is to reverse them (see table). Each confirmation takes between a few seconds and 90 minutes, with 10 minutes being the average. If the transaction pays too low a fee or is otherwise atypical, getting the first confirmation can take much longer.
Examples of coupled irreversible processes like the thermoelectric phenomena, the transference phenomena in electrolytes and heat conduction in an anisotropic medium are considered. For certain cases of such interaction reciprocal relations have been deduced by earlier writers, e.g., Thomson's theory of thermoelectric phenomena and Helmholtz' theory for the e.m.f. of electrolytic cells with liquid junction. These earlier derivations may be classed as quasi-thermodynamic; in fact, Thomson himself pointed out that his argument was incomplete, and that his relation ought to be established on an experimental basis. A general class of such relations will be derived by a new theoretical treatment from the principle of microscopic reversibility. (1-2.) The analogy with a chemical monomolecular triangle reaction is discussed; in this case a a simple kinetic consideration assuming microscopic reversibility yields a reciprocal relation that is not necessary for fulfilling the requirements of thermodynamics (3). Reciprocal relations for heat conduction in an anisotropic medium are derived from the assumption of microscopic reversibility, applied to fluctuations. (4.) The reciprocal relations can be expressed in terms of a potential, the dissipation-function. Lord Rayleigh's "principle of the least dissipation of energy" is generalized to include the case of anisotropic heat conduction. A further generalization is announced. (5.) The conditions for stationary flow are formulated; the connection with earlier quasi-thermodynamic theories is discussed. (6.) The principle of dynamical reversibility does not apply when (external) magnetic fields or Coriolis forces are present, and the reciprocal relations break down. (7.)
Some climate variables do not show the same response to declining atmospheric CO2 concentrations as before the preceding increase. A comprehensive understanding of this hysteresis effect and its regional patterns is, however, lacking. Here we use an Earth system model with an idealized CO2 removal scenario to show that surface temperature and precipitation exhibit globally widespread irreversible changes over a timespan of centuries. To explore the climate hysteresis and reversibility on a regional scale, we develop a quantification method that visualizes their spatial patterns. Our experiments project that 89% and 58% of the global area experiences irreversible changes in surface temperature and precipitation, respectively. Strong irreversible response of surface temperature is found in the Southern Ocean, Arctic and North Atlantic Ocean and of precipitation in the tropical Pacific, global monsoon regions and the Himalayas. These global hotspots of irreversible changes can indicate elevated risks of negative impacts on developing countries.
The absolute difference between xdown and xup holds the hysteresis area always positive. Reversibility of a system can be measured as whether the trajectory return to its initial state, indicated as an open-loop (irreversible change) and closed-loop (reversible change):
Note that an open-loop trajectory does not always indicate that a system is completely irreversible. Even if the loop is open, there is a possibility that the system will returns to its initial state if sufficient time is provided after the forcing reaches the initial level22. Nevertheless, at least, they show that the climate system cannot be immediately restored to its initial state even after successful removal of the atmospheric CO2. The soft definition of irreversibility provides a practical classification for climate recoverability within a human-perceptible timescale.
Focusing on comprehensive response in climate variables, we identified hotspots of irreversible climate changes over the land based on the quantified hysteresis and reversibility. The hotspot for irreversible climate change is defined as a land region where both surface temperature and precipitation show an open-loop response with a large hysteresis area (Methods provide detailed criteria).
The hotspot map is presented in Fig. 4. Under our idealized CO2 forcing scenario, the hotspots emerge in most developing countries24 located in South America and Africa, such as Chile, Venezuela, Brazil, Nigeria, Ethiopia and Zimbabwe. Developing countries in Central America and South Asia are also classified as the hotspot. In contrast, only a few developed countries24 are classified as the hotspots, such as Ireland and New Zealand. The contrast between developing and developed countries implies a strong regional inequality in climate reversibility to anthropogenic global warming. The strong irreversible changes in developing countries translate into the long-lasting impact of anthropogenic CO2 emissions, which would vastly increase the risks of climate change with great social costs25,26,27.
The identified hotspots for irreversible changes are marked in red. A hotspot is defined as the land area where both surface temperature and precipitation show an open-loop response (irreversible change) and a large hysteresis area (>50th percentile) to the CO2 forcing.
The hotspots also emerge in the regions covered with ice sheets, coastal regions of Antarctica, Greenland and Alaska. Large hysteresis and irreversible changes in these regions can potentially cause the hysteresis in ice sheets7,28,29 and marine ecosystems30,31. The polar hotspots highlight the irreversibility of polar regions to CO2 emissions.
Although the detailed dynamical process differs between regions, a fundamental mechanism for hysteresis and reversibility can be broadly modelled as an inertia effect. The multi-stability is also a possible mechanism for them35,36,37,38, but the inertia effect is a more reasonable hypothesis in this case (Supplementary Discussion 1). The inertia induces a delayed response to CO2 forcing and can result in hysteresis and irreversible changes. Here we present a simple inertia model for hysteresis and reversibility
The hotspot of irreversible changes is detected based on the annual mean land surface temperature and precipitation. The hotspot is defined as the land area where both surface temperature and precipitation show open-loop response and hysteresis area larger than its 50th percentile.
Decisions fall somewhere on the continuum from reversible to irreversible. You can tell where a decision lies on this spectrum by asking how much it would cost to undo. The higher the cost to undo, the more irreversible it is. The lower the cost, the more reversible it is.
When decisions are irreversible, slow them down. The biggest risk is making the wrong decision. The cost to get the information we need to reduce uncertainty is worth the time and effort.
Russian President Vladimir Putin now faces an \"irreversible\" quagmire amid the country's land grab in its ongoing invasion of Ukraine, retired Army general and former CIA chief David Petraeus said Sunday.
Two studies published this week conclude that a section of the West Antarctic ice sheet has reached a point of inevitable collapse, an event that would eventually raise sea levels more than a meter (three-plus feet). The first study, led by Eric Rignot of the Jet Propulsion Laboratory, used NASA satellite and airborne observations to measure how glaciers have been retreating in the region. The other study, led by Ian Joughin of the University of Washington, used a computer model to compare observations of recent melting with projected melt scenarios to see which matches reality best so far. Both studies conclude that the Amundsen Sea segment of the ice sheet has begun an irreversible decline that will result in its loss, possibly as soon as the next few hundred years.
Mount Sinai surgeons are always searching for new ways to treat cancer through research and clinical trials. We are now using irreversible electroporation (IRE) to treat several types of cancerous tumors successfully.
In administering IRE, we insert one or more thin probes into the tumor and deliver short electrical pulses into the tumor. This step causes disruption of the pores located within the cancer cell membranes, interfering with the cellular function of the cancer. This causes irreversible damage which leads to cell death and tumor necrosis.
While the effects of human activities on Earth's climate to date are irreversible on the timescale of humans alive today, every little bit of avoided future temperature increases results in less warming that would otherwise persist for essentially forever. The benefits of reduced greenhouse gas emissions occur on the same timescale as the political decisions that lead to those reductions. 041b061a72