Great leaders recognize the weak signals or slight signs that point to big changes to come.

Wireless devices will transmit signals so as to activate the alarm once something wrong is detected.

That approach will eliminate most cord-cutting concerns—but what about their wireless equivalent, jamming? With the right device tuned to the right frequency, what's to stop a thief from jamming your setup and blocking that alert signal from ever reaching the base station?Jamming concerns are nothing new, and they're not unique to security systems.

If they detect something wrong while the system is armed, they'll transmit a wireless alert signal to a base station that will then raise the alarm.

Any device that's built to receive a wireless signal at a specific frequency can be overwhelmed by a stronger signal coming in on the same frequency.

So when a French submarine (潛水艇) detected the device's homing signal five days later, the discovery marked a huge step toward determining the cause of a tragedy in which 152 passengers were killed.

When submerged, they're also able to emit signals from depths of 20,000 ft.

Homing signals sent by the pilot before the crash

They have stopped sending homing signals.

For example, a Colombian who wants someone to approach him often signals with a hand movement in which all the fingers of one hand, cupped, point downward as they move rapidly back and forth.

Were they tuned off because an American had the nerve to instruct Japanese in their own art form or they deliberately tried to signal their rejection of her?

Learning how different cultures signal respect can help you avoid misunderstandings

with the right device tuned to the right frequency, what's to stop a thief from jamming your setup and blocking that alert signal from ever reaching the base station?

Their behaviors do not constitute a warning signal.

Scholars warn that Antarctica's political drift could blur the distinction between military and civilian activities long before the continent's treaties come up for renegotiation, especially in parts of Antarctica that are ideal for intercepting ( ' , 攔截) signals from satellites or retasking satellite systems, potentially enhancing global electronic intelligence operations.

It provides new early-warning signals for identifying teens in trouble.

LOL signals basic empathy)'(同感)between texters.

The Home Depot approach to craftsmanship - simplify it, dumb it down, hire a contractor - is one signal that mastering tools and working with one's hands is receding in America as a hobby, as a valued skill, as a cultural influence that shaped thinking and behavior in vast sections of the country.

They signal future economic trends

Over the past two years, the figures on imports and exports seem not to signal a double-dip recession –?a renewed decline in the broad level of economic activity in the United States?–?but an economic expansion.

It signals decreasing domestic demand for goods and services.

To test how responsive dolphins are to various signals.

Were they tuned off because an American had the nerve to instruct Japanese in their own art form or they deliberately tried to signal their rejection of her?

Learning how different cultures signal respect can help you avoid misunderstandings

Beyond revealing population-wide patterns, the right combination of data and analysis can also help individuals identify unique characteristics of their own behavior, including conditions that could indicate the need for some form of intervention-such as