On the doors of La Paz Residence Hall signs that read: "Do you like loud, annoying and obnoxious sounds?" confront residents as they come and go.

The signs are posted to warn residents about holding the doors open too long÷something that can allow strangers to enter the halls. The alarm system that will sound if a door is held open is one of the latest of several new security features that school officials hope will make living in residence halls safer.

In addition to the wired doors at La Paz, residence halls across campus are under a lockdown, with at least all the exterior doors being locked 24 hours.

Police presence has also been stepped up and students have been instructed to follow some steps that department of Residence Life director Jim Van Arsdel calls "simply a matter of common sense and behavior."

Van Arsdel said that there are a handful of ways students living in the residence halls can to ensure their own safety, as well as that of their neighbors, such as not propping doors open, not allowing people they do not know into the buildings and politely challenging anyone who looks like they do not belong in the halls by asking that person what his or her business is there.

Resident assistants held mandatory meetings in all the halls Sunday night, in which they informed residents of what roles everyone in the halls needs to play.

"The RAs gave us the rules and regulations and a lot of information about what's on campus," Emily Prendergast, a microbiology freshman and resident in Kaibab-Huachuca Residence Hall, said. "I feel really safe."

"Safety is an issue we're hitting hard as something we're concerned about and hope that the students will also be concerned about," Van Arsdel said. "We can do everything anyone could ever think of, but all it takes is one person propping a door open, and we have a problem."

UAPD Commander Brian Seastone said liaison officers are also distributing whistles with lights on them that students can use in the event of an emergency.

Both the lockdown and a campaign to hand out safety whistles began last spring, following a string of sex-related crimes on campus. Van Arsdel said the police and security presence was stepped up following last year's attacks.

UAPD Commander Brian Seastone said control units randomly but often patrol the residence halls, including the university's apartment communities.

"There is nothing in the world that anyone can do to guarantee the complete security of any space," Van Arsdel said. "Sometimes things break."

Van Arsdel said some of the halls are also experimenting with locking corridor doors within the halls to see if students accept it and if it accomplishes anything.

Jennifer Anderson, a French education junior who works at the front desk in Yuma Residence Hall, said that she thinks the security precautions are working and that they are "a necessary step and really beneficial because of the incidents that happened at the end of last year."

Julie Dwyer, a pre-business sophomore and Yuma resident, said, "I feel pretty safe with the security measures and locked doors 24-hours-a-day. It can be kind of a pain, but I think it's all worth it."

"Before, you could have people come in any time; now you have to make sure you escort guests everywhere," Dwyer added. "In light of what happened last year, it's worth it. It's a smart thing."