My first Mac

It’s been thirty years since the Apple Macintosh was introduced on 24 January 1984. To celebrate the milestone, Apple have posted a Thirty Years of Mac feature on their website highlighting some of the key machines introduced over the period and stories from prominent users. It also invites visitors to enter information about their first Mac – data is collated to determine the most popular machines and how people used their Macs.

Paper Mac and PowerBook G4

This is the only photo I could easily find of my first Mac – an Apple PowerBook G4 (12-inch, 1.33 GHz) from 2004. It’s there with its distinctive glowing Apple logo behind the Paper Mac. It was miles ahead of my old Dell laptop in terms of portability, design, power… and the sheer cool factor back in the days when Apple products were still niche.

We’ve come a long way since 2004 – x86 has replaced PowerPC, multi-core processors, solid-state drives, six major releases of Mac OS X, display technology has advanced from 106 ppi TN to 220 ppi IPS, &c. – but I’ll always feel a sense of nostalgia about my first Mac.

Canberra parking meters

Whilst in Canberra recently, I came across the following parking meter on Lonsdale St – an American POM Model N housing with modernised internals. This style of parking meter is also common in parts of the Melbourne CBD, but is rarely seen in Sydney (if at all) having been superseded years ago.

Canberra parking meter

I quickly noted several issues with this traditional-style meter (not counting the fact that it doesn’t accept credit card payments nor 5c/50c coins).

1. Parking rate is not clearly marked

The rates are printed on a sticker within the “window” section at the same size and weight as the rest of the text in that section. Whilst I acknowledge that there is only limited space within that section, the text could be bold or colour could be used to draw attention to what is generally the most important piece of information to the user. (I presume a sticker affixed to the housing would not be viable due to vandalism).

2. Parking rate expressed in unusual increments

Most people have a time interval in mind when paying for parking and want to know how much it would cost to pay for that interval (e.g. $3/hour). The ACT government presumably thinks that people have a monetary amount in mind and want to know how much parking time can be purchased for a given amount – I can’t think of any other reason why the rate is expressed in the unusual manner above “10c = 2 mins” and “20c = 4 mins” (i.e. $3/hour). Also, Canberrans apparently can’t multiply by 2 and need it stated as above but then mysteriously seem to be able to multiply by 30 (to calculate the hourly rate).

I did see/use modern parking ticket machines in other parts of the city, so hopefully the city will eventually make the transition. Don’t get me started, however, on the inconsistent road signs, multiple models of traffic lights, etc. – that’s a rant for another day…

Sherlock: transforming the Tube

It was great to see the return of BBC’s Sherlock with series three’s opening episode The Empty Hearse (spoiler alert). Others have already commented that there were inconsistencies in scenes that took place in the Tube (London Underground), some of which are particularly obvious because of the division of the Tube network into sub-surface lines and deep-level lines with different rolling stock used on each line. A few of the more obvious things I noticed:

Not the District line

St James's Park security footage

The supposed security footage of a train running on the District line between Westminster and St James’s Park actually shows a deep-level tube station and train, either a 1996 Stock (Jubilee line) or 1995 Stock (Northern line). In real life, St James’s Park station is only served by sub-surface lines (District line and Circle line) running D Stock and S Stock trains.

Bigger on the inside

London Underground 1967 Stock

When Sherlock and Watson find the missing train car sitting in a disused tunnel, it’s now mysteriously transformed into a 1967 Stock train (formerly used on the Victoria line). When they enter the train, however, our protagonists find themselves inside a sub-surface D Stock train (District line). It’s bigger on the inside! (Is it a coincidence that co-creators Steven Moffat and Mark Gatiss also work on Doctor Who?) But at last the train shown is consistent with the plot.

London Underground D Stock

I’m sure there were good logistical reasons for all the swaps – it’s likely that the producers used whatever footage and sets were available rather than incurring the expense of building new ones just for consistency.

eGFR vs CrCl

Estimated glomerular filtration rate (eGFR) and creatinine clearance (CrCl) are often, incorrectly, used interchangeably when discussing renal function and drug dose adjustment.

Creatinine clearance, usually estimated using the 1976 Cockcroft-Gault formula rather than actually measured by (notoriously unreliable) 24-hour urine collection, has traditionally been used for drug dosing as it is relatively standardised despite overestimating renal function due to tubular secretion of creatinine. In addition to the usual caveats associated with basing renal function estimates on serum creatinine (acute illness, muscle mass, diet, etc), accuracy of the formula is limited by changes to serum creatinine assays and the rise in obesity since 1976.

Renal function is assessed nowadays using formula-derived eGFR (actual GFR is impracticable to measure routintely). Until recently this was usually calculated using the MDRD formula (1999), which has been well validated but has limited accuracy above 60 mL/min. Laboratories in Australia now report eGFR calculated using the superior CKD-EPI formula (2009). Although both of these formulae give better estimates of true renal function (GFR) than CrCl, they are both still based on serum creatinine with its associated caveats above.

Some studies have shown a reasonable concordance between CrCl (Cockcroft-Gault) and eGFR (MDRD) with respect to drug dosing,1 whereas others have noted significant differences.2–3 At the end of the day, CrCl and eGFR are not the same thing and prescribers should remain vigilant as to which measurement has been used to formulate dosage adjustment recommendations.

1. Stevens LA, et al. Am J Kidney Dis 2009;54:3342
2. Wargo KA, et al. Ann Pharmacother 2006;40:124853
3. Park EJ, et al. Ann Pharmacother 2012;46:117487

Biotechnology descriptors

Whilst giving a presentation at grand rounds recently, I noted that approved names for biological medications in Australia are suffixed with a three-letter abbreviation – the “biotechnology descriptor” – to indicate the biotechnology production system used, e.g. insulin lispro (rbe).

The most common biotechnology descriptors are:

  • ghu – gene-activated human cell line
  • rbe – recombinant bacteria Escherichia coli
  • rch – recombinant Chinese Hamster ovary cell line
  • rmc – recombinant mouse cell line
  • rys – recombinant yeast Saccharomyces cerevisiae

Incidentally, I cringe whenever someone refers to this group of medications as “biologics” – an Americanism that has crept into the Australian medical lexicon. Australian English still retains the “-ical” ending (rather than shortening to “-ic” in American English), therefore we should continue to refer to these medications as “biologicals”.

Marking the border

There are some places in the world where you barely know that you’re crossing a border – even an international one – such as when driving on the M1/A1 between Dublin and Belfast in the Republic of Ireland and the United Kingdom respectively. The only indication that you’ve crossed into another country is a road sign stating that speed limits are now expressed in miles per hour or kilometres per hour, depending on which direction you’re travelling. There are historical and political reasons for this, of course.

Australian state borders, on the other hand, tend to be clearly marked. Within the twin towns of Tweed Heads NSW and Coolangatta QLD, apart from the usual signs, there is the following marker on Boundary Street.

NSW–Queensland border marker, Boundary Street

The majority of people crossing the border, however, bypass the towns and instead see this abstract sculpture on the M1 Pacific Motorway.

NSW–Queensland border, M1

I suppose it has to be obvious, in case the poorly designed Queensland road signs (one of which is visible above) don’t clue you in to the fact that you’ve crossed the border!