今年美国签证形势整体开始发生转变，敏感专业的审查周期从以前的长达两个月缩短到2~3周，且因专业审查而遭遇申请失败的人数极少。但是，如果申请者所学的专业属于敏感专业，为了能按时到达学校，一定要提早向所在辖区的大使馆或者领事馆申请签证。

　　美国留学 敏感专业详细列表

　　The State Department maintains a Technical Alert List, also known as the sensitive major list, to guide their evaluation of visa submission.

　　Sorted by rate.

　　CRITICAL FIELDS LIST

　　A. CONVENTIONAL MUNITIONS: Technologies associated with:

　　-- Warheads and other large caliber projectiles

　　-- Reactive armor and warhead defeat systems

　　-- Fusing and arming systems.

　　-- Electronic countermeasures and systems

　　-- New or novel explosives and formulations

　　-- Automated explosive detection methods and equipment

　　B. NUCLEAR TECHNOLOGY: Technologies associated with

　　production and use of nuclear material for both peaceful and military applications. Included are technologies for:

　　-- Enrichment of fissile material

　　-- Reprocessing irradiated nuclear fuel to recover produced

　　plutonium

　　-- Production of heavy water for moderator material

　　-- Plutonium and tritium handling

　　Also, certain associated technologies related to nuclear physics and/or nuclear engineering. Includes materials,equipment or technology associated with:

　　-- Power reactors, breeder and production reactors

　　-- Fissile or special nuclear materials

　　-- Uranium enrichment, including gaseous diffusion,centrifuge, aerodynamic, chemical, Electromagnetic Isotopic Separation (EMIS), Laser Isotope Separation

　　(LIS)

　　-- Spent fuel reprocessing, plutonium, mixed oxide nuclear research

　　Inertial Confinement Fusion (ICF)

　　-- Magnetic confinement fusion

　　-- Laser fusion, high power lasers, plasma,

　　-- Nuclear fuel fabrication including Mixed Oxide (uranium-

　　plutonium) fuels (MOX)

　　-- Heavy water production

　　-- Tritium production and use

　　-- Hardening technology

　　C. ROCKET SYSTEMS (including ballistic missile systems,space launch vehicles and sounding rockets) and Unmanned Air Vehicles (UAV) (including cruise missiles, target drones, and reconnaissance drones): Technologies associated with rocket systems and UAV systems. The technology needed to develop a satellite launch vehicle is virtually identical to that needed to build a ballistic missile.

　　D. ROCKET SYSTEM AND UNMANNED AIR VEHICLE (UAV) SUBSYSTEMS:

　　Propulsion technologies include solid rocket motor stages,and liquid propellant engines. Other critical subsystems include re-entry vehicles, guidance sets, thrust vector controls and warhead safing, arming and fusing. Many of these technologies are dual-use. Technologies include:

　　-- Liquid and solid rocket propulsion systems

　　-- Missile propulsion and systems integration

　　-- Individual rocket stages or staging/separation mechanism

　　-- Aerospace thermal (such as superalloys) and high-performance structures

　　-- Propulsion systems test facilities

　　E. NAVIGATION, AVIONICS AND FLIGHT CONTROL USEABLE IN ROCKET SYSTEMS AND UNMANNED AIR VEHICLES (UAV): These capabilities directly determine the delivery accuracy and lethality of both unguided and guided weapons. The long-term costs to design, build and apply these technologies have been a limiting proliferation factor. Technologies include those associated with:

　　-- Internal navigation systems

　　-- Tracking and terminal homing devices

　　-- Accelerometers and gyroscopes

　　-- Rocket and UAV and flight control systems.

　　-- Global Positioning System (GPS)

　　F. CHEMICAL, BIOTECHNOLOGY AND BIOMEDICAL ENGINEERING: The technology used to produce chemical and biological weapons is inherently dual-use. The same technologies that could be applied to develop and produce chemical and biological weapons are used widely by civilian research laboratories and industry; these technologies are relatively common in many countries. Advanced biotechnology has the potential to support biological weapons research. In the biological area, look for interest in technologies associated with:

　　-- Aerobiology (study of microorganisms found in the air or in aerosol form)

　　-- Biochemistry

　　-- Pharmacology

　　-- Immunology

　　-- Virology

　　-- Bacteriology

　　-- Mycology

　　-- Microbiology

　　-- Growth and culturing of microorganisms

　　-- Pathology (study of diseases)

　　-- Toxicology

　　-- Study of toxins

　　-- Virulence factors

　　-- Genetic engineering, recombinant DNA technology

　　-- Identification of nucleic acid sequences associated with pathogenecity

　　-- Freeze-drying (lyophilization)

　　-- Fermentation technology

　　-- Cross-filtration equipment

　　-- High "DOP-rated filters" (e.g., HEPA filters, ULPA filters)

　　-- Microencapsulation

　　-- Aerosol sprayers and technology, aerosol and aerosolization technology

　　-- Spray or drum drying technology

　　-- Milling equipment or technology intended for the production of micron-sized particles

　　-- Technology for eliminating electrostatic charges of small particles

　　-- Flight training

　　-- Crop-dusting, aerosol dissemination

　　-- Unmanned aerial vehicle (UAV) technology

　　-- Fuses, detonators, and other munitions technology

　　-- Submunitions technology

　　-- Computer modeling of dissemination or contagion

　　-- Chemical absorption (nuclear-biological-chemical (NBC) protection)

（编辑：Ada）