![]() ![]() Indeed, the company claims this is all part of a three-year plan to “stabilize profitability and position the company for growth” – an increasingly common mea culpa for traditional retailers slow to adopt bold new strategies for success in the age of Amazon. Whether it does so remains to be seen.” Prof. Some analysts, like Neil Saunders of GlobalData Retail, were less than sympathetic, pointing out that Macy’s “failed to evolve, and it’s now facing the consequences.” But Saunders also noted, via Twitter, something of a silver lining: “With fewer stores, Macy’s has an opportunity to evolve, adapt and invest. In early February, following a disappointing holiday sales season, the legacy retailer announced it will close 125 stores, lay off roughly 2,000 employees, and shutter most of its San Francisco-based tech operation. Suffice it to say that Macy’s did not get what it wanted for Christmas, and is taking it pretty hard. ![]() In the cable this capacitance is between theĪxial wire and shield is analogous to the membrane capacitance of an axon.Twitter thread by Neil Saunders, of GlobalData Retail, on Macy’s Feb. ![]() As a voltage signal spreads along the cable or axon, there is a delay and loss of amplitude as current is gradually lost via the capacitance ( Cm) or via leakage through the insulation ( rm). In the axon the external low resistance is the extracellular space). The resistance of the inside wire (or axoplasm) carrying the signal is represented by the string of resistors ( ra) along the top of the diagram.The cable's equivalent circuit is shown as segments representing discrete lengths, perhaps a mile each the junction of each segment is connected to the external low-resistance shield. In the axon this current flows through the ion channels. The current through the insulation itself ( rm), which is proportional to the signal voltage.This current through the capacitance is directly proportional to the rate of change of the signal voltage. In the cable the insulation is the rubber between the two plates of the capacitor (the wire and the external shield of the cable) in the axon, the insulation is the lipid between the two plates of the capacitor (the axoplasm and the extracellular space. The currrent through the capacitance ( Cm) offered by the insulation. ![]() The current (here labeled Im) is composed of two parts: The labels on the figure correspond to parts of an axon rather than of a cable. The figure here shows the current along the inside of the wire or axon and also through the cable's insulation or the axon's membrane (which is, of course, its insulation). This equation describing the transmission of a voltage signal along a section of the cable is a \partial differential equation for voltage as a function of time and space.Ī similiar partial differential equation applies equally well to an axon with voltage-sensitive ion channels. Lord Kelvin in 1855 developed what is commonly called the cable equation to describe the attenuation and distortion of signals in the first Atlantic cable. ![]()
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