Weaken

Some common synonyms of weaken are cripple, debilitate, disable, enfeeble, sap, and undermine. While all these words mean "to lose or cause to lose strength or vigor," weaken may imply loss of physical strength, health, soundness, or stability or of quality, intensity, or effective power.

weaken

Dear Doctors: About a year ago, when I turned 44, I started using reading glasses that I purchased at the drug store and they seemed to work just fine. Now I need a stronger pair and I wonder whether using them has weakened my eyes.

Cancer can weaken the immune system by spreading into the bone marrow. The bone marrow makes blood cells that help to fight infection. This happens most often in leukaemia or lymphoma, but it can happen with other cancers too. The cancer can stop the bone marrow from making so many blood cells.

Certain cancer treatments can temporarily weaken the immune system. This is because they can cause a drop in the number of white blood cells made in the bone marrow. Cancer treatments that are more likely to weaken the immune system are:

Thousands of Israelis have been protesting a proposal to weaken Israel's judiciary. Earlier this week, Prime Minister Benjamin Netanyahu agreed to delay the changes that he and his right-wing allies want. But protesters still object to an overhaul that they say would politicize the court system. Many Palestinians and Arab Israelis say the Israeli courts are already deeply politicized. Our co-host, Michel Martin, spoke with Sawsan Zaher about this. Zaher is a human rights attorney and a Palestinian citizen of Israel.

Drinking a lot of alcohol is known to suppress our immune system. It weakens our bodies and makes it harder to combat stress, viruses, and diseases. Dietitians recommend sticking to one drink per day for women or two drinks per day for men.

ARs are narrow long bands of enhanced moisture fluxes originating from the mid-latitudes and sub-tropics16. They have been associated with particular instances of high temperature, moisture, and wind speed in the lower troposphere17,18,19 along with sometimes co-occurring with foehn winds while causing major melt events20,21 and being linked with instances of sea-ice decay22. However, a systematic long-term analysis of extreme events co-occurring with ARs still needs to be conducted along the AP to show their role in ice-shelf weakening and the eventual initiation of ice-shelf calving and disintegration events.

Here, we used an AR detection algorithm previously utilized for studying Antarctic AR climatology, Antarctic ice sheet precipitation, and melt events in West Antarctica23, a polar-specialized regional climate model, Modèle Atmosphérique Régional24 (MAR), driven by ERA-5, and a series of satellite observations (see Methods) to retrieve calving events, surface melt occurrences, swell heights, and sea ice extent around the AP. We analyze the link between ARs and the Larsen A and B ice-shelf calving and collapses and the major influence of AR on the processes behind ice-shelf weakening (i.e., extreme temperature, surface melt, runoff, melt pond formation, sea-ice removal, ocean swell and sea-level height-induced ice-shelf flexure, foehn wind, and iceberg calving). Particularly we address the probability of intense ARs generating compound extreme events linked to ice-shelf collapse triggers.

Consequently, AR landfalls prompt a state of high stress on the ice shelves through the combination of surface melt induced melt pond formation, leading to hydrofracturing and wave strain along the ice-shelf front. The tendency of ARs to create widespread melt pond formation makes them possible precursors of ice-shelf collapse via hydrofracturing cascades like what was observed on the Larsen B in 200213. This combined with wind stress and radiative forcing leading to sea-ice clearing thus allowing swells to apply strain along the ice-shelf fronts14,22 makes ARs a unique forcing of ice-shelf weakening. These conditions occur during periods of enhanced poleward heat advection from anticyclonic activity just east of the northern AP36 (Supplementary Fig. 1). Figure 4 provides a visualization summarizing all the processes during AR landfalls that are linked to ice-shelf weakening. The AR example in the schematic showcases an AR making landfall perpendicular to the ice shelf and generating a foehn wind along with the associated sensible heat, downward longwave, and downward shortwave radiative fluxes as the airflow adiabatically warms and dries over the leeward ice shelves while causing sea-ice disintegration and swells along the ice-shelf front.

We studied other possible connections between ARs and ice-shelf weakening and did not find conclusive evidence for a direct relationship between AR activity and ice-shelf basal melting, one of the long-term precursors of ice-shelf collapse37. Indeed, looking at ocean hindcasts from 1979 to 201838, we did not find any significant correlation between either yearly AR frequency or yearly cumulative maximum IVT and either the ocean temperature at the depth of the ice-shelf drafts or Ekman pumping (a driver of basal ice-shelf melt variations39) near Larsen or Wilkins ice shelves. For a single weather event, a previous study showed that a major sea surface height anomaly in front of the Amery ice shelf may have contributed to trigger a calving event40. However, looking at sea surface height anomalies in the global ocean simulations from 1979 to 201538, we did not identify any noteworthy sea surface height anomalies associated with ARs on both sides of the AP.

When AR strength and impacts are characterized by considering landfall duration in addition to the maximum IVT upon landfall, like the scale used to classify ARs in western North America41, consistent relationships between AR intensity and various impacts emerge. As the cumulative maximum IVT of the AR increases, the more likely a temperature extreme, melting extreme, sea-ice disintegration or high-swell event occurs (Fig. 4). This is visible in Fig. 6a, where AR intensity is assessed by summing the maximum IVT values throughout the day when an AR is detected. Taken as a whole, all these events represent a physical state that promotes ice-shelf weakening as confirmed by the co-occurring calving and even collapse events with AR landfalls. For the most intense ARs at landfall, there is a nearly 20% probability of a daily temperature, melt, or runoff extreme occurring over at least half the lower-elevation portion of the northern AP (blue line and area; see Fig. 6d for domain). There is an increase in probability when the same calculation is repeated but with the added option of a substantial sea-ice decline occurring (up to 40%, red line and area), and with the option of a high-swell event east of the AP (green line and area).

A new study found that even if we did have the infinite power to artificially cool enough of the oceans to weaken a hurricane, the benefits would be minimal. The study led by scientists at the University of Miami (UM) Rosenstiel School of Marine, Atmospheric, and Earth Science showed that the energy alone that is needed to use intervention technology to weaken a hurricane before landfall makes it a highly inefficient solution to mitigate disasters.

To scientifically answer questions about the effectiveness of artificially cooling the ocean to weaken hurricanes, the authors used a combination of air-sea interaction theories and a highly sophisticated computer model of the atmosphere.

In their computer simulations, they cooled areas of the ocean up to 260,000 km2 in size - larger than the state of Oregon and equating to 21,000 cubic kilometers of water - by up to 2 degrees Celsius. Even with the largest area of cooling, the simulated hurricanes weakened by only 15 percent. The amount of energy extracted from the ocean to achieve this small reduction is equivalent to more than 100 times the amount consumed across the entire United States in 2019 alone.

Abstract. The probability that plant communities undergo successive climate extremes increases under climate change. Exposure to an extreme event might elicit acclimatory responses and thereby greater resistance to a subsequent event, but might also reduce resistance if the recovery period is too short or resilience too low. Using experimental herbaceous plant assemblages, we compared the effects of two successive extremes occurring in one growing season (either two drought extremes, two heat extremes or two drought + heat extremes) to those of assemblages being exposed only to the second extreme. Additionally, the recovery period between the successive extremes was varied (2, 3.5 or 6 weeks). Among the different types of climate extremes, combined heat + drought extremes induced substantial leaf mortality and plant senescence, while the effects of drought and heat extremes were smaller. Preceding drought + heat extremes lowered the resistance in terms of leaf survival to a subsequent drought + heat extreme if the recovery period was two weeks, even though the leaves had completely recovered during that interval. No reduced resistance to subsequent extremes was recorded with longer recovery times or with drought or heat extremes. Despite the substantial mortality on the short term, the drought + heat and the heat extremes increased the end-of-season aboveground biomass independent of the number of extreme events or the duration of the recovery period. These results show that recurrent climate extremes with short time intervals can weaken the resistance of herbaceous plant assemblages. This negative effect in the short term can, however, be compensated in the longer term through rapid recovery and secondary positive effects.

As we grow older, our skeletal muscles tend to wither and weaken, a phenomenon known as sarcopenia. Sarcopenia, which begins to appear at around age 40 and accelerates after 75, is a major cause of disability in the elderly. Exercise can help counter the effects of age-related muscle loss. Otherwise, there are no established treatments. 041b061a72