BSF

BSF may refer to:

BSF (time service)

BSF is the callsign of the time signal transmitter for Taiwan, which transmits time information on 77.5 kHz in the longwave range, and 5 MHz & 15 MHz in the shortwave range from Chung-Li. The transmitter, which uses a T-antenna is situated at 25°0′20″N 121°21′54″E / 25.00556°N 121.36500°E / 25.00556; 121.36500 (BSF Time Signal Transmitter).

Longwave transmitter

The longwave transmitter of the station uses 1 kW of power, achieving an effective radiated power of 460 W. 120 bits of information are transmitted each minute using amplitude-shift keying, whereby five basic states can be transmitted, encoding either pair of bits or a special synchronization mark:

Shortwave transmitter

The shortwave transmitter on 5 MHz operates continuously, while that on 15 MHz has an interruption between 35 and 40 minutes after the hour. The shortwave transmitters transmit during the five-minute intervals, with odd-count second pulses of 5 ms duration and 1 kHz modulation, and even-count second pulses of 5 ms without modulation. For 40 ms before and after the pulse, there is no modulation with the 1 kHz tone. Minute pulses have a length of 300 ms.

Interleukin 4

The interleukin 4 (IL4) is a cytokine that induces differentiation of naive helper T cells (Th0 cells) to Th2 cells. Upon activation by IL-4, Th2 cells subsequently produce additional IL-4 in a positive feedback loop. The cell that initially produces IL-4, thus inducing Th0 differentiation, has not been identified, but recent studies suggest that basophils may be the effector cell. It is closely related and has functions similar to Interleukin 13.

Function

It has many biological roles, including the stimulation of activated B-cell and T-cell proliferation, and the differentiation of B cells into plasma cells. It is a key regulator in humoral and adaptive immunity. IL-4 induces B-cell class switching to IgE, and up-regulates MHC class II production. IL-4 decreases the production of Th1 cells, macrophages, IFN-gamma, and dendritic cell IL-12.

Overproduction of IL-4 is associated with allergies.

Inflammation and wound repair

Tissue macrophages play an important role in chronic inflammation and wound repair. The presence of IL-4 in extravascular tissues promotes alternative activation of macrophages into M2 cells and inhibits classical activation of macrophages into M1 cells. An increase in repair macrophages (M2) is coupled with secretion of IL-10 and TGF-β that result in a diminution of pathological inflammation. Release of arginase, proline, polyaminases and TGF-β by the activated M2 cell is tied with wound repair and fibrosis.