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Posts Tagged science & society

zombies & lego – great combination! Alison Campbell Dec 02

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Actually, that’s a bit of a fib as the zombies & the lego don’t actually meet in these videos :) But both have a science focus.

Lego is the focus of a clip called ‘Building Curiosity’, which is something of an ode to science; I rather enjoyed it.

And the zombies? Well, you’re likely to encounter the animated undead on a place like the Discworld, where they tend to have an issue with bits falling off at inopportune moments. But the flesh-eating urge? Just might be possible…

Enjoy!

weapons-grade foolishness from the ‘food babe’ Alison Campbell Nov 18

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Today, we move on to just plain, flaming, weapons-grade foolishness. Foolishness that is, unfortunately, spread to a rather wide audience.

Vani Hari is the self-described ‘Food Babe’, on a mission to ‘make America’s food safer’. According to Ms Hari, if you can’t pronounce a food item’s ingredients, you shouldn’t be eating it1. I guess she’s never seen information like this, then (graphic by the wonderful James Kennedy).

Ingredients of an All-Natural Banana

But I digress. Recently Ms Hari wrote a piece giving her advice around flying. (It’s since been removed from her site, but the internet has ways of ensuring that things don’t just disappear, so you can read the post in its entirety here – for as long as it remains there, or there’s a screen cap here.) The nature of some of her comments do not inspire me with confidence.

A few facts about what airplanes do to your body -

When your body is at seriously high altitude, your body under goes [sic] some serious pressure. Think about it – Airplaines thrive in places we don’t. You are traveling in a pressurized cabin, and when your body is pressurized, it gets really compressed!

I am still trying to get my head around the idea of inanimate objects like aeroplanes ‘thriving’. That aside, our bodies are not placed under greater pressure when at altitude. Yes, plane cabins are pressurised, but that pressure’s still less than what we’re exposed to at sea level.

Compression leads to all sorts of issues. First off your body’s digestive organs start to shrink, taxing your ability to digest large quantities of food. Secondly, this compression reduces the ability for your body to normally circulate blood through your blood vessels. Sitting down for long hours while this is happening, exacerbates these issues, leading to what they call “Economy Class Syndrome.” Economy Class Syndrome results the action [sic] of sitting in a cramped space for a long period of time, thus resulting in blood flow loss to the legs.

Yes, aeroplane passengers are subject to increased risks relating to poor circulation, but they’ve got nothing to do with ‘compression’ due to supposedly high cabin pressure & everything to do with simply sitting still in cramped conditions for prolonged periods of time. In fact, air travellers are advised to use compression stockings to help mitigate those risks. (Ms Hari does give some sensible advice on combatting this.)

The air you are breathing on an airplane is recycled from directly outside of your window. That means you are breathing everything that the airplanes gives off and is flying through. The air that is pumped in isn’t pure oxygen either, it’s mixed with nitrogen, sometimes almost at 50%. To pump a greater amount of oxygen in costs money in terms of fuel and the airlines know this! The nitrogen may affect the times and dosages of medications, make you feel bloated and cause your ankles and joints to swell.

This is such a basic science fail. Passengers don’t breathe in ‘everything the airplane gives off’ (details of where cabin air comes from are here). And Earth to Vani: the air you breathe has never been ‘pure oxygen’, whether you’re at ground level or 11,000m up in the air – probably just as well, really, given the reactivity of the pure stuff. This is so easily checked (image from geocraft.com):

Now, this may seem laughable. Someone is ill-informed & shares that lack of knowledge rather widely. But that’s not doing any actual harm, is it?

Except, I think it is. Why? Because the Food Babe is encouraging and pandering to chemophobia and scientific illiteracy (and, sad to say, has a wide audience for this nonsense: several hundred thousand followers on FB, for example). And when you’re also spreading anti-vaccine misinformation to that number of followers then yes, you have real potential to do harm.

 

1 Sad to say, one of our local NZ companies has bought into the ‘no long words’ meme. It’s worth remembering that some ‘nasties’ have very short names, while the names of many important proteins are multisyllabic.

a tale of rare blood groups, or, ‘the man with the golden blood’ Alison Campbell Nov 03

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One of the topics we cover in first-year biology is human blood groups – it’s discussed during genetics classes & also touched on when looking at how immune systems function. I give the genetics classes and, being a regular blood donor myself, thought I knew a bit about at least the common blood groups and their inheritance. But there’s always more to learn, something I was reminded of when I read a fascinating story about people with truly rare blood types: “The man with the golden blood”.

There’s ‘Thomas’, for example: a man who lacks the Rhesus markers completely & so is classified as Rhnull  - in 2010 he was one of an exclusive global club of 43 individuals (of whom only 6 regularly donate their blood). And James, who is ‘Lutheran b negative’, and one of only 550 active donors for this blood type.

This makes known donors precious, in that if someone else with the same group needs a blood transfusion, there are very very few people around the globe who might be able to help them. And helping comes at a cost to the donors, for – as the story tells us – it’s actually easier in many cases to move people across borders than it is to move blood, but because many countries don’t pay donors, then that movement may well be at the donor’s expense. It’s also difficult for people like ‘Thomas’, with his vanishingly rare blood group: his blood can be used by anyone who’s Rhesus negative, but he can receive blood only from another Rhnull person, which means he has to be reasonably careful not to put himself in harm’s way (although he does still go skiing!).

Quite an eye-opener – and a tale I’ll be including in next year’s class.

6-second science Alison Campbell Jun 23

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This video is a compilation of the best clips from the ‘Six-second science fair’ run by GE recently. (Apparently it attracted more than 600 entries!)

Could be really interesting to set something like this as a classroom project – rapidly changing technology (including the apps) has really opened up the options :)

thoughts from a conference: scientists and science communication Alison Campbell Feb 17

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I spent much of today at an international symposium on “Transforming Public Engagement on Controversial Science & Technology”. It’s been fascinating & I’m looking forward to day 2, having learned a lot from both the formal presentations and the round-table discussions. I also got to lead a discussion session after a keynote address by fellow sciblogger Shaun Hendy (hi Shaun!), who looked at the reasons scientists do – & don’t – get into science communication. Set the questions “should scientists be active in science communication, should they be ‘brokers’ of science knowledge or take on more of a ‘science advocacy’ role, and how best should we (society) support them in doing so, the participants came up with quite an extensive list. I’ve riffed on them a bit here in the hope that this may engender even more discussion.

  • Which scientists? Are we talking natural/physical scientists, or should the net be broadened to include social scientists, political scientists, & so on? Should we distinguish between them – there’s a case to me made for closer cooperation between the various disciplines (something of a ‘hybrid’ model). Also, do we really want open slather – there’s a risk of dilution of effort if everyone should happen to get involved. It could be better to have clear ‘go-to’ people for the media, in particular. (Here, of course, we need to remember that there are many ways to get involved in science communication. Fronting to the media is important, yes, but there are other avenues: presenting at Cafe Scientifique or science-in-the-pub events, helping schools during primary science week, & speaking to general interest groups spring to mind, but I’m sure there are many more.)
  • Science vs knowledge: science is only one lens for viewing the world; we also need discussions around ethical implications of novel technologies, for example. (Our table had an involved discussion, in a later session, around different cultural perspectives on assisted reproductive technologies, which had nothing at all to do with the mechanics of the actual technologies, and everything to do with the social and cultural impacts of both the application of those technologies and the very words we use to talk about them.) We can’t talk about science without also considering the social context in which it’s set, and the question of what society does with the science is up to society as a whole (or its elected representatives).
  • Communication may involve education around a particular aspect of science; advocacy (for the process, the nature, of science or for a particular application – although here you’d surely be moving into the realm of opinion?), or about policy issues. All must be evidence-based. Scientists are also citizens, and it’s not possible for us to be entirely objective about our work. We need to be clear about whether we’re communicating around our particular field of expertise, as compared to advocating for a particular action. And there does need to be discussion about and engagement with the nature of science, as well as the results of that science (advocacy for the scientific method, if you will).
  • Science communication is a two-way street: we need to listen and learn, as well as speak out.
  • We need to consider other forms of communication besides the spoken & written word – here Siouxsie Wiles and her glow-in-the-dark squid sprang immediately to mind :) More interactivity, more ‘non-traditional’ modes of communication!
  • Scientists are used to taking time to consider their responses to queries, while the media require quick (if not immediate) answers to requests for information. Shaun touched on this, too, as one of the reasons that some scientists may be reluctant to get involved in dealing with the members of the fourth estate.
  • Issues around conflicts of interest, memoranda of understanding, and confidentiality may affect individuals’ availability, willingness, and freedom to speak. The nature of the particular discipline, sources of funding, and potential impacts on job security may also influence decisions.
  • Why would scientists communicate? Should they? In a different, more scientifically-literate world, maybe we wouldn’t have to. Or there might not be so much need, anyway. However, these days, with very few specialist science journalists in the media, the need remains. As to the ‘why would we’ part, as Shaun noted, there are many potential reasons. Some – I think very few – do it simply as a means to raise their own profile or attract more funding. We may do it through sheer frustration with the way the media or society deal with scientific issues. But probably most scientists involved in science communication do it in the hope of making a difference; we’re usually motivated by a sense of social responsibility or by an interest in a particular issue. (I originally got into science blogging, for example, as a means of supporting secondary biology teachers and students.)
  • Scientists don’t always have to work though the media but may work in the community at the request of that community on local initiatives.
  • How do we enable scientists to communicate about what they do? Basically this activity needs to be incentivised, by funding and/or official recognition. (Writing science blogs, no matter how solid the science in them or how widely they’re read and discussed, doesn’t count in the PBRF stakes.) We also need to respect the work of those who don’t communicate; it’s not something that everyone can or should get into.
  • It’s a real challenge to communicate the uncertainty of science. This is something I’ve noticed in the fluoride debates, for example. People want a degree of certainty in their lives, while science is never 100% certain – though we may speak of an issue being ‘effectively settled’, there remains that hint of uncertainty. This can be unsettling, and it can work against science in some forums.
  • It’s also a challenge, at times, to avoid issues with equivalence or ‘false balance’. The media in particular are keen on presenting ‘both sides’ when from a scientific perspective there’s only one. (Hence we’ll sometimes see stories on vaccination paired with claims that this is linked to autism, or on evolution ‘balanced’ by the views of intelligent design proponentsists, for example. And no, that was not a spelling mistake on my part.)

Please feel free to add to or comment on any of these points!

fluoridation in the news Alison Campbell Feb 04

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I didn’t intend to write another post on this subject so soon after the last one, but a story on yahoo.com’s news feed has really annoyed me. I know journalists these days are seriously under pressure, but that doesn’t really justify taking a ‘press release’ from a known activist organisation and running it uncritically ie without actually looking into any of the claims made therein. You’ll find the story here, & I’m going to comment on some of the claims it contains below. (I would have done it directly on the yahoo.com piece but they don’t actually allow comments, grumble grumble mutter.)

Dr Paul Connett is currently visiting NZ and Australia to promote the views of the anti-fluoridation organisation FAN and its antipodean sub-groups. While he has reportedly spent 17 years ‘researching’ issues associated with community water fluoridation (CWF), he has published neither original research papers on this particular topic nor a systematic review of the existing scientific literature, in leading science journals. He has, however, published a book on the subject, the contents of which formed the basis of an extensive discussion on the Open Parachute science blog (also syndicated to the Science Media Centre’s sciblogs.co.nz). This output doesn’t really justify the ‘expert’ description so adroitly promoted by the FANNZ spokesperson who provided the yahoo item.

Repeated calls for a ‘debate’ are rather misleading as they suggest that there is in fact something to debate. In the case of the science behind CWF, as Sir Peter Gluckman has said, it is effectively settled. To call for a debate is simply an attempt to sow doubt and fear in people’s minds, and any such event would be ‘won’ by the better demagogue and not necessarily on the basis of the actual science presented. Thus it makes perfect sense for TV3 to seek comment from Dr Jonathan Broadbent, who has a solid research record around oral health, rather than to opt for the flawed ‘debate’ format & so give some feeling of false equivalency to an issue where none exists.

The FANNZ claim that our health officials are “[advocating] a highly toxic chemical be added to the drinking water of over 2 million people” is an attempt to imply that this practice is doing harm. However, there is no good evidence that the fluoridated water coming from the taps actually causes significant adverse health effects. Nor have health officicals “gone into hiding” (as stated in the yahoo story), as Dr Broadbent’s willingness to be interviewed clearly demonstrates,

What are the facts that FANNZ is so keen for New Zealanders to hear? The organisation certainly seems keen to obscure the evidence that community water fluoridation improves oral health (here, here, and here, for example) and is a cost-effective way of doing so. The spokesperson comments that it “is [health officials'] responsibility to provide people with real factual information” – and appears to be ignoring the fact that the National Fluoride Information Service has been set up to do just that. And just today dental health experts have provided commentary on fluoridation via the Science Media Centre.

As I’ve said, many large-scale systematic reviews have found that there is good evidence that ingesting fluoride reduces decay – and, contrary to the claim in the original press release – the evidence of “unacceptable health risks” is not “growing daily”. For example, the claim that fluoride is implicated in development of osteosarcoma appears to be based on a single preliminary study, and is not supported by more recent large-scale analyses. Similarly the ‘Harvard’ review, often cited as evidence that fluoridation affects IQ, has a number of flaws, some of which were identified by the authors themselves.

Yahoo.com, it’s a real pity you didn’t look into this one rather more deeply.

the science-based medicine blog on fluoridation Alison Campbell Jan 22

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This is something that I posted on Making Sense of Fluoride, but thought I’d re-post here; it deserves to be widely read. I’ve highlighted some of the main points made by the authors as they address issues frequently raised by those opposed to community water fluoridation.

The Science-Based Medicine blog is an excellent resource and well-worth adding to your regular reading list. A few days ago Clay Jones (a paediatric hospitalist) & Grant Ritchey (DDS) posted an article entitled “Preventing Tooth Decay in Kids: Fluoride and the Role of Non-Dentist Health Care Providers“. It’s reasonably long but contains a number of key points.

The first is that “there are a number of stumbling blocks that prevent children from receiving appropriate dental care” – including distance from/accessibility to a provider, not to mention the costs involved.

Secondly, that the majority of people will be affected by caries: ” [r]oughly 90% of us will have some degree of tooth decay during our lifetime”; that this prevalence increases over time, and that – sadly but unsurprisingly – it is most marked in poorer sectors of society. Interestingly they also characterise caries as infectious – because the bacteria involved can be & are spread from mouth to mouth. (Consequently they advise against ‘spit-cleaning’ a child’s dummy, which sounds just about as insanitary as popping it straight back in from a sojourn on the floor.) And there’s also a genetic component, which means that “[t]ooth decay truly is a complex, multifaceted process that clearly isn’t as simple as forgetting to floss every day or even the socioeconomic status.”

There’s a description of the effect of fluoride on tooth enamel, which says quite explicitly that “when exposed to fluoride either systemically during tooth development or topically via toothpaste, fluoridated water, or professional application, becomes strengthened.” Jones & Ritchey agree that dental and skeletal fluorosis are problems when ingesting higher levels of fluoride, but add a caveat that bears repeating: “It must be emphasized that skeletal and severe fluorosis of the teeth do not occur as a result of any sort of community water fluoridation, or because of fluoride in toothpastes or professional fluoride treatments [my emphasis]. They occur in areas with naturally occurring fluoride levels far in excess of what is safe, and are rare in the United States. In these areas, a defluoridation process must be undertaken to return the water concentration of fluoride to safe and optimal levels.”

And they have some strong words to say on the so-called ‘fluoride controversy’.

As I said, it’s a long-ish piece but well worth reading in its entirety.

For those interested in reading more on this issue, my colleague Ken Perrot has written extensively on fluoridation over at Open Parachute: here, for example.

shaking up the academy? or, how the academy could shake up teaching Alison Campbell Dec 10

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This is something I originally wrote for my ‘other’ blog over at Talking Teaching.

Last week I spent a couple of days down in Wellington, attending the annual symposium for the Ako Aotearoa Academy. The Academy’s made up of the winners of the national Tertiary Teaching Excellence Awards, so there are around 150 or so of us now. While only 35 members were able to make it to this year’s event (& the executive committee will survey everyone to see if there’s a better time – having said that, everyone seems so busy that there’s probably no date that would suit everyone!), we had a great line-up of speakers & everyone left feeling inspired & energised. I’ll blog about several of those presentations, but thought I would start with one by Peter Coolbear, who’s the director of our parent body, Ako Aotearoa.

Peter began by pointing out that the Academy is potentially very influential – after all, it’s made up of tertiary teachers recognised at the national level for the quality of their teaching, & who foster excellence in learning & teaching at their own institutions.  But he argued – & I agree with him - that there is room for us to become involved in the wider scene. Peter had a number of suggestions for us to consider.

First up, there’s a lot going on in the area of policy – are there areas where the Academy might be expected to have & express an opinion? For example

  • There’s the latest draft of the Tertiary Education Strategy (TES), which ”sets out the Government’s long-term strategic direction for tertiary education; and its current and medium-term priorities for tertiary education.” There’s a link to the Minister’s speech announcing the launch of the draft strategy here.
  • In addition, the State Services Commission’s document Better Public Services: results for New Zealanders sets out 10 targets across 5 areas. Targets 5 & 6 are relevant here as they are a reference point for government officials looking at evidence for success in the education sector. (Such scrutiny is likely to become more intense in light of the 2012 PISA results, which have just been made public.) Target 5 expects that we’ll “[increase] the proportion of 18-year-olds with NCEA level 2 or equivalent qualification”; #6 is looking for an increase in “ the proportion of 25 to 34-year-olds with advanced trade qualifications, diplomas and degrees (at level 4 or above)”. This will increase the pressure on institutions to increase retention & completion rates – might this have an effect on standards?
  • There’s also the requirement to achieve parity of success for ‘priority’ learners, especially Maori & Pasifika – this is priority #3 in the TES. (Kelly Pender, from Bay of Plenty Polytech, gave an inspirational presentation on how he weaves kaupapa Maori into pretty much everything he does in his classroom, in an earlier session.) And it’s an important one for us to consider. Peter cited data from the Ministry of Education’s website, ‘Education Counts’, which showed significantly lower completion rates for Maori & Pasifika students in their first degrees compared to European students, and commented that this will likely become a major issue for the universities in the near future.
  • If we’re to meet those achievement requirements, then how institutions scaffold learners into higher-level study, through foundation & transition programs, will become increasingly important. What are the best ways to achieve this?
  • Peter predicted increased accountability for the university sector (including governance reform). Cycle 5 of NZ’s Academic Audits has begun, and ”is to be framed around academic activities related to teaching and learning and student support.” This is definitely one I’d expect Academy members to have an opinion on!
  • He also expects strengthened quality assurance processes throughout the education sector: this suggests a stronger (& more consistent) role for the  NZ Qualifications Authority, with the development of partnership dialogues across the sector (ie including universities).

Then, at the level of the providers (ie the educational institutions themselves – & that’s not just the polytechs & universities), we have:

  • a targeted review of qualifications offered at pre-degree level – there’s background information here;
  • a government-led drive to get more learners into the ’STEM’ subjects (science, technology, engineering, & maths) – this poses some interesting challenges as at university level we’re seeing quite a few students who’ve not taken the right mix of subjects, at the right NCEA level, to go directly into some of the STEM papers they need for, say, an engineering degree;
  • the rise in Massive Open On-line Courses, or MOOCs. (I find these quite strange creatures as they are free to the student and typically attract very large enrolments, but also apparently have very low completion rates. What’s in them for the institution? A good way of offering ‘taster’ courses that hook students in?)
  • the likelihood that we will see the development of a system for professional accreditation of tertiary teachers (I’ve written about this previously and will write another post fairly soon, as accreditation was the subject of a thought-provoking session at the symposium);
  • how we achieve protection of academic standards – it’s possible that government policies (eg those linking funding to completion & retention rates)may result in a tendency to exclude of underprepared kids &/or lowering standards – neither is desirable but both are possible results of those policies.

That’s a big list and the Academy can’t do everything! So, what should it focus on? (This is not a rhetorical question – it would be great to get some discussion going.) The Academy, in the person of its members, is effectively a resource; a body of expertise – can it become a ‘go-to’ body for advice? Speaking personally I think we need to make that shift; otherwise we remain invisible outside our individual institutions & the teaching-focused activities we’re involved in, & in a politicised world that’s not a comfortable thing to be. Can we, for example, better promote the significance of teaching excellence outside the education sector? Become involved in the discussions around & development of any accreditation scheme? Develop position papers around maintaining teaching excellence in the context of the new TES?

What do you think? And what shall we, collectively, do about it? 

fluoridation: an attempt to silence science, and false equivalence Alison Campbell Aug 23

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This morning’s Waikato Times features the attention-grabbing front-page headline: “Anti-fluoride campaigner tries to silence science“. I guess the debate is really heating up when someone from one side tries to get the other side to shut up…

It would be appreciated if we could receive some confirmation from the chemistry department that it will remain publicly neutral on the matter.

To be fair to the anti-fluoride lobby, the letter to the Chemistry Department at the University of Waikato came from a single member of the local Hamilton group. Note to the organisers of Fluoride Free Hamilton – if you are not in support of this letter, it would be really nice to hear you say so. Publicly.

The letter reproduced by the Waikato Times includes the statement that

At Fluoride Free Hamilton we intend to limit the debate to the social science and public health aspects of fluoridation.

Now, I actually think that it would be good to have a reasoned, well-informed debate on social issues relating to fluoridation. Is ‘mass medicalisation’ the way to go, for example? If fluoride isn’t delivered this way, then how do we deal with the social costs entailed in some members of society not accessing it? How much, as a society, are we responsible for our poorest members?

Unfortunately that’s not really the way things have shaped up to date. Instead the HCC tribunal that made the original decision to stop fluoridation, the letters/opinion columns of our various local papers, & on-line discussions of media reports have been awash with dubious & frankly scaremongering claims about the ills of fluoridation. For example

that in drinking fluoridated water we’re forced to drink acid  - No, we’re not. (Presumably those making this claim don’t eat citrus fruit, or drink wine or a certain caffeinated fizzy beverage.)

that hydrofluorosilicic acid adds harmful levels of heavy metals to our water supply – No, it doesn’t.

that fluoride is neurotoxic and lowers children’s IQs – again, at concentrations found in municipal supplies, no, it doesn’t. (Did they even read the original paper?)

that fluoride ‘narcotises’ salmon at levels well below those present in municipal supplies – No, it doesn’t - the original paper says nothing about this.

and so on, and on, and on… I am moved to ask (again) – if the anti-fluoridation activists are so sure of their case, then why do they need to distort, cherrypick, and misquote science in order to support it? You’re entitled to your own opinions, folks, but not your own versions of the facts.

We’re also seeing a fair amount of false equivalence here, where the anti-fluoridation groups would argue that their ‘science’ is equivalent to the science put forward by (for example) the District Health Board & my chemistry colleagues. In fact there is no equivalence – how can there be, when those claims (above) are examined & found wanting?

 

 

once more into the fluoride ‘debate’, dear friends Alison Campbell Aug 08

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This week’s Hamilton Press (a local free newspaper) has a lot of fluoride-focused letters in its opinion pages. After reading them I must ask, again, why those opposed to fluoride need to misrepresent the evidence if their case is so strong.

For example, we’re told about Amsterdam GP Dr Hans Moolenburgh, who apparently noticed those children in his practice who were drinking fluoridated water were developing colic. (Ulcers & eczema were also attributed to this ion.) Incidentally much of the letter’s content seems to be cribbed from on-line sources such as this.

“These sudden pains only took place in fluoridated Heemstede, and the cure was easy: Non-fluoridated water.”

Now – aside from the issues of why fluoride, in the very low concentrations added to drinking water, would cause colic, and how likely it is that we’re seeing confirmation bias – this ‘cure’ would seem quite significant. So, where are the publications relating to it, that would draw the attention of the medical world? Yes, I know he’s written a book. But a search of pubmed and the NIH database (using the terms moolenburgh+holland+fluoride+colic) drew a blank. Searches using scirus.com & google Scholar brought up a paper citing Moolenburgh, but no actual peer-reviewed publications. (Incidentally that paper is in the publication Fluoride, which does not appear to be an independent journal.)

This is really odd, because the letter writer goes on to say that Dr Moolenburgh got together a research team that

eventually conducted a double-blind experiment, the results of which clearly established there was a definite relationship between the symptoms and fluoride in water. Following publication of their research results, water fluoridation in Holland was discontinued in 1976.

I would really quite like to read this research paper, except so far I’ve not been able to find anything that matches what our writer describes. Just what was their double-blind set-up, and their intervention? For it to be a double-blind study then none of the researchers should know where their patients came from, for example.

Also, while it is correct that the Netherlands no longer fluoridate their municipal water supplies, fluoridated salt is available. Indeed, as the paper I’ve just linked to points out, if a country’s major discounters sell only fluoridated salt, then that’s what everybody gets.

I’ll get onto the next letter later.

 

 

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