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。

　　 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

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