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Something I’ve never done before January 29, 2009

Posted by dorigo in internet, personal.
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: advertising here.

Sorry for using this space for pointing at information on a house for sale. I cannot neglect the opportunity that this blog provides for finding potential buyers… So if you are not interested in buying an apartment in Venice (my father’s), I apologize for the inconvenience. Otherwise, have a look.

Cosmic-ray studies of the CMS tracker January 28, 2009

Posted by dorigo in news, personal, physics.
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It is always nice to open the web browser in the morning, check the arxiv for new interesting preprints, and be surprised to find one’s own name in the author list. That is what happened to me today, while browsing lazily the list of new hep-ex papers, as my eyes set on “Performance studies of the CMS strip tracker before installation”.

The paper describes the full testing of a sector of the CMS tracker. The tracker (see picture on the right, showing a detail of its inner barrels) is a daring device made of many concentric barrels of silicon strip sensors. During the summer of 2007 a quarter of the device was fully instrumented, cooled, and read out while it was being exposed to cosmic rays, and a total of 4.5 million tracks were reconstructed, allowing to gain critical experience with its operation, and detailed studies of its tracking capabilities, the tuning of a simulation of the detector, and the development of advanced tools.

Of course I knew the paper was being prepared -the submitter is Patrizia Azzi, a member of my group in Padova (although she’s full-time at CERN)- but no, I did not contribute to it in any significant way and no, I had not even read the draft!

To be fair, the author list includes over 400 names, the members of the CMS Tracker Collaboration (people who were somehow involved in the construction of the tracker), so you should not run out screaming “Dorigo is a parasite!” -at least, I am not the only one! This is how things work in large collaborations: you focus on one or two studies at a time, on the time-scale of two-three years, but you do not just sign your papers: you sign all of them.

In retrospect, I should be even less severe with myself.  Although the paper contains no results of mine, I did work on the analysis of the data. I did a study of multi-track events, trying to figure out how the presence of large amounts of hits close together could affect the tracking (a matter of relevance for LHC, where dozens of tracks will pack together within small volumes), and I studied the extraction of the angle of incidence of tracks from the width of clusters of charge in the silicon strips (tracks crossing a layer of silicon at normal incidence leave a ionization trail which gets collected in few strips, while tracks crossing with a large angle leave a signal in many adjoining strips).

Those studies did not end up providing a valuable addition to the paper -mostly because I did not conclude them- and they were left out of it, but I invested at least one month of work in them. Not much, but I do not feel a parasite after all: the paper is maybe the result of 20 or 30 man-years of studies, so each of the 400 authors contributed an average of less than one month of full-time work!

Information control from CERN January 27, 2009

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A piece by Matthew Chalmers titled “CERN: the view from inside” has appeared yesterday on Physics World’s web site. It is an insightful interview to James Gillies, head of communications at CERN.

The interview focuses mostly on the media coverage of the LHC startup of last September 10th, and the steps that made it a global success, with an estimated exposure of one billion people. The point is made that now “LHC” can be used out of context without problems, but I hope the revenues to science are larger than that.

More interesting to us science bloggers is the description of how information on the September 19th incident was provided by CERN, and the measures that were put in place to prevent unwanted, uncontrolled news from leaking out in blogs and other unauthorized media. The LHC logbook was edited, pictures of the incident were password-protected. I do not think this is too worrysome: the management decided it was the best thing to do under the exceptional circumstances, and I do not blame them for being tight.

The piece ends up discussing the restrictive policy of the lab and its experiments to blogging. The point is made that unconfirmed rumors damage science, but the matter is not really discussed in detail in any way. People keep claiming that discussion of unconfirmed signals is nocuous to Science, but I continue to hear that it is nocuous to their interests. Do director generals want to be the ones releasing important lab information to protect us, or to protect their chair ? Do principal investigators insist that results are released only after a publication is sent to the journal to avoid waves of imprecise physics from being distributed to unarmed citizens, or to increase their exposure when they make an announcement ?

I insist on being naive on this matter. I think that scientific results on basic science do not belong to their discoverers, nor to the experimental collaboration: they, as much as the data they are based upon, belong to the people.

In the Physics World interview, Gillies claims that the lab will act to counter the public discussion of not-yet-confirmed three-sigma effects (the article  mentions this corresponds to a “less than 1% chance for a statistical fluke”, but I guess it was Matthew to get this inaccurate to simplify matters for his numerically-challenged audience -the probability  is actually 0.3%). Well, I think the laboratory will have to be very careful to get down to the level of bloggers: the CERN management seems to talk and think as if blogging was a controllable phenomenon, but believe me, it ain’t. Not until they close the whole internet thing down.

In May 2007 an anonymous comment left in my blog on a large signal of supersymmetric Higgs decays seen by the D0 collaboration in events with four b-quark jets started a runaway phenomenon which ended on the New York Times and on Slate, plus other media around the world. The D0 collaboration was not happy about it, but what could they do ? The answer is simple: nothing. I wonder whether the CERN experiments have aces up their sleeves instead…

Multi-muon news January 26, 2009

Posted by dorigo in news, personal, physics, science.
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This post is not it but no, I have not given up on my promise to complete my series on the anomalous multi-muon signal found by CDF in its Run II data. In fact, I expect to be able to post once more on the topic this week. There, I hope I will be able to discuss the kinematic characteristics of multi-lepton jets. [I am lazy today, so I will refrain from adding links to past discussions of the topic here: if you need references on the topic, just click on the tag cloud on the right column, where it says "anomalous muons"!]

In the meantime, I am happy to report that I have just started working at the same analysis for the CMS experiment! In Padova we have recently put together a group of six -one professor, three researchers, a PhD student, and a undergrad- and we will pursue the investigation of the same signature seen by CDF.  And today, together with Luca, our new brilliant PhD student, I started looking at the reconstruction of neutral kaon decays K^\circ \to \pi^+ \pi^-, a clean source of well-identified pion tracks with which we hope to be able to study muon mis-identification in CMS.

Meanwhile, the six-strong group in Padova is already expanding. Last Wednesday professor Fotios Ptochos, a longtime colleague in CDF, a good friend, and crucially one of the authors of the multi-muon analysis, came to Padova and presented a two-hour-long seminar on the CDF signal in front of a very interested group of forty physicists spanning four generations -from Milla Baldo Ceolin to our youngest undergraduates. The seminar was enlightening and I was very happy with the result of a week spent organizing the whole thing! (I will have to ask Fotios if I can make the slides of his talk available here….)

Fotios, a professor at the University of Cyprus, is a member of CMS, and a true expert of measurements in the B-physics sector at hadron machines. We plan to work together to repeat the controversial CDF analysis with the first data that CMS will collect -hopefully later this year.

The idea of repeating the CDF analysis in CMS is obvious. Both CDF and D0 can say something on the signal in a reasonable time scale, but whatever the outcome, the matter will only be settled by the LHC experiments. Imagine, for instance, that in a few months D0 publishes an analysis which disproves the CDF signal. Will we then conclude that CDF has completely screwed up its measurement ? We will probably have quite a clue in that case, but we will need to remain possibilistic until at least a third, possibly more precise, measurement is performed by an independent experiment.That measurement is surely going to be worth a useful publication.

And now imagine, on the contrary, that the CDF signal is real…

Is acupuncture effective ? January 23, 2009

Posted by dorigo in news, science.
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I have always been highly sceptical on the utility of acupuncture, as much as on any other “alternative medicine” techniques. Man has practiced the most diverse healing techniques since thousands of years ago, and the lack of knowledge of the placebo effect has hampered the effectiveness of the “trial and error” approach, which on general grounds should be expected to slowly evolve and end up producing good results, given enough time. Some empirical techniques have survived to this day, and the onset of a scientific approach to medicine has not marginalized them as much as one would think reasonable.

To be fair, acupuncture should not be placed at the same level of deception as homeopathy, which is really just placebo dressed up with a pseudo-scientific dusting, with the aggravating condition that it is a parasitic technique of modern medicine, being based on active molecules known to be beneficial for the pathology they try to cure.

While homeopathy is based on the irrational and totally groundless belief that water remembers molecular structures it has come in contact with, acupuncture targets nerves of the human body, and those nerves are indeed connected to the central nervous system. It is quite possible that hitting the right nerves “distracts” the brain such that it alleviates the sensation of pain coming from other parts of the body. This is not such a far-fetched claim, after all: compared to water memory, it looks like good science.

Rigorous studies of the effectiveness of acupuncture therefore seem to be worth much more attention and funding than those on homeopathy. And studies have been done and are under way, focusing on the different applications of nerve stimulation techniques. The methods of investigation typically consist in comparing the response to therapy of patients treated with acupuncture to that of patients where acupuncture was applied to random parts of the body, not targeting the nerves it is supposed to aim at.

I have taken some time today to have a look at all the studies I could locate in the library of the Cochrane Collaboration, a serious institution which reviews the results of clinical studies. The Cochrane collaboration web site contains more than two dozen studies addressing the effect of acupuncture and similar techniques on the treatment of specific pathologies. I put together a list of those studies below, quoting from their abstracts the conclusions they draw. An interesting picture emerges.

  • Acupuncture for acute stroke: There is no clear evidence of benefit from acupuncture in acute stroke. [...] Serious adverse effects were uncommon, and occurred in about one in every hundred patients treated.
  • Acupuncture for insomnia: Currently there is a lack of high quality clinical evidence supporting the treatment of people with insomnia using acupuncture.
  • Acupuncture-point stimulation for chemotherapy-induced nausea or vomiting: Electroacupuncture reduced first-day vomiting, but manual acupuncture did not. Acupressure reduced first-day nausea, but was not effective on later days. Acupressure showed no benefit for vomiting. Electrical stimulation on the skin showed no benefit. All trials also gave anti-vomiting drugs, but the drugs used in the electroacupuncture trials were not the most modern drugs, so it is not known if electroacupuncture adds anything to modern drugs. Trials of electroacupuncture with modern drugs are needed.
  • Acupuncture and related interventions for smoking cessation: The review did not find consistent evidence that active acupuncture or related techniques increased the number of people who could successfully quit smoking. However, acupuncture may be better than doing nothing, at least in the short term; and there is not enough evidence to dismiss the possibility that acupuncture might have an effect greater than placebo.
  • Acupuncture for dysphagia in acute stroke: Only one small randomised controlled trial was identified, involving 66 participants, which did not provide clear evidence of benefit from adding acupuncture to standard Western medical treatment. Considering the small sample size and methodological imperfections, there is insufficient evidence to determine the effectiveness of acupuncture.
  • Acupuncture and assisted conception: The data from this meta-analysis suggests that acupuncture does increase the live birth rate with in vitro fertilisation (IVF) treatment when performed around the time of embryo transfer. However, this could be attributed to placebo effect and the small number of trials included in the review.
  • Acupuncture for vascular dementia: There is no evidence from randomized controlled trials to determine whether acupuncture provides any effect when treating people with vascular dementia. Acupuncture is used to treat vascular dementia, but because no randomized controlled trials of acupuncture versus placebo were found, its efficacy and safety could not be analysed in this review. There is a need for randomized placebo controlled trials of acupuncture for people with vascular dementia.
  • Acupuncture and electroacupuncture for the treatment of rheumatoid arthritis: In one study, people had acupuncture or fake therapy for five weeks, once per week. Pain, number of swollen and tender joints, disease activity, overall well-being, lab results, or amount of pain medication needed was about the same whether they had acupuncture or fake therapy. In the other study, people had acupuncture with an electric current going through the needles at specific or real acupuncture spots in the knee or at fake spots in the knee. Knee pain while at rest, while moving or while standing decreased more in the people who had the real acupuncture. The improvement lasted up to 4 months after acupuncture. Unfortunately, the authors of this review believe that this trial was of low quality and may overestimate how well acupuncture works.
  • Acupuncture and dry-needling for low back pain: Thirty-five RCTs covering 2861 patients were included in this systematic review. There is insufficient evidence to make any recommendations about acupuncture or dry-needling for acute low-back pain. For chronic low-back pain, results show that acupuncture is more effective for pain relief than no treatment or sham treatment, in measurements taken up to three months. The results also show that for chronic low-back pain, acupuncture is more effective for improving function than no treatment, in the short-term. Acupuncture is not more effective than other conventional and “alternative” treatments. When acupuncture is added to other conventional therapies, it relieves pain and improves function better than the conventional therapies alone. However, effects are only small. Dry-needling appears to be a useful adjunct to other therapies for chronic low-back pain.
  • Acupuncture for migraine prophylaxis: We reviewed 22 trials which investigated whether acupuncture is effective in the prophylaxis of migraine. Six trials investigating whether adding acupuncture to basic care (which usually involves only treating acute headaches) found that those patients who received acupuncture had fewer headaches. Fourteen trials compared true acupuncture with inadequate or fake acupuncture interventions in which needles were either inserted at incorrect points or did not penetrate the skin. In these trials both groups had fewer headaches than before treatment, but there was no difference between the effects of the two treatments. In the four trials in which acupuncture was compared to a proven prophylactic drug treatment, patients receiving acupuncture tended to report more improvement and fewer side effects. Collectively, the studies suggest that migraine patients benefit from acupuncture, although the correct placement of needles seems to be less relevant than is usually thought by acupuncturists.
  • Acupuncture for restless legs syndrome: There is insufficient evidence to support the use of acupuncture for the symptomatic treatment of restless legs syndrome. The review did not find consistent evidence to determine whether acupuncture is effective and safe in the treatment of RLS, based on the two trials identified. More high quality trials are warranted before the routine use of acupuncture can be recommended for patients suffering from RLS.
  • Acupuncture for Bell’s palsy: This review aimed to review systematically all randomised controlled trials and controlled clinical trials, which examined the effectiveness of acupuncture for Bell’s palsy. Six studies including a total of 537 participants met the inclusion criteria. Five studies used acupuncture while the other used acupuncture combined with drugs. No trials reported on the outcomes specified for this review. Harmful side effects were not reported in any of the trials. Flaws in study design or reporting (particularly whether the process of assigning people to different groups was hidden and also substantial losses to follow-up), and clinical differences between trials prevented conclusions about the efficacy of acupuncture. The quality of the included trials was inadequate to allow any conclusion about theefficacy of acupuncture. More research with high quality trials is needed.
  • Acupuncture for glaucoma: We did not find any randomized clinical trials on the subject. The limited information from a few case series highlights the gap in the existing evidence. At this point, the effectiveness of acupuncture as a therapeutic modality for glaucoma could not be established.
  • Acupuncture for depression: There are studies indicating a preference for treatment with self-help and complementary therapies for depression. This review examined the efficacy and adverse effects of acupuncture in treating depression. Based on the findings from seven trials of low quality, there is insufficient evidence to determine whether acupuncture is effective in the management of depression.
  • Interventions (other than pharmacological, psychosocial or psychological) for treating antenatal depression: There is not enough evidence available to determine if maternal massage or depression-specific acupuncture interventions are effective in treating antenatal depression. The review found only one trial involving 61 US women evaluating maternal massage and depression-specific acupuncture (the insertion of needles into the tissue for remedial purposes) for the treatment of antenatal depression. This trial provided insufficient evidence to determine if these therapies are effective treatment for antenatal depression. Further research is needed.
  • Acupuncture for tension-type headache:We reviewed 11 trials which investigated whether acupuncture is effective in the prophylaxis of tension-type headache. Two large trials investigating whether adding acupuncture to basic care (which usually involves only treating unbearable pain with pain killers) found that those patients who received acupuncture had fewer headaches. Forty-seven percent of patients receiving acupuncture reported a decrease in the number of headache days by at least 50%, compared to 41% of patients in the groups receiving inadequate or ‘fake’ acupuncture. Three of the four trials in which acupuncture was compared to physiotherapy, massage or relaxation had important methodological shortcomings. Their findings are difficult to interpret, but collectively suggest slightly better results for some outcomes with the latter therapies. In conclusion, the available evidence suggests that acupuncture could be a valuable option for patients suffering from frequent tension-type headache.
  • Auricular acupuncture for cocaine dependence:The authors searched the medical literature for studies called randomized controlled trials, in which one group of patients receives  treatment (such as acupuncture) and is compared with a similar group who receives a different treatment or no treatment (the control group). The authors found seven studies with a total of 1433 people. Most of the studies compared acupuncture with ‘sham’ acupuncture in which needles were inserted into random places in the ear but not into the specific points required for treatment. The studies used a variety of acupuncture techniques, using three, four, or five of the treatment points. The studies had a number of problems with the way their results were reported. The authors conclude that there is no evidence that any form of auricular acupuncture is effective for treating cocaine dependence.
  • Acupuncture for schizophrenia: This review identifies randomised controlled trials comparing acupuncture to antipsychotics and acupuncture combined with antipsychotics, to antipsychotics alone. The limited data we found provided mostly equivocal outcomes. Although some of the data did favour acupuncture when combined with antipsychotics, the results came from small studies, and further, more comprehensive trials are needed before we can confidently determine the efficacy of acupuncture in the treatment of schizophrenia.
  • Acupuncture for chronic asthma: The studies included in the review were of variable quality and had inconsistent results. Future research should concentrate on establishing whether there is a non-specific component of acupuncture which benefits recipients of treatment. There should be an assessment not merely of placebo treatment, but also of ‘no treatment’ as well. There is insufficient evidence to make recommendations about the value of acupuncture as a treatment for asthma based on current evidence.
  • Acupuncture for epilepsy: Patients with epilepsy are currently treated with antiepileptic drugs, but a significant number of people continue to have seizures and many experience adverse effects to the drugs. As a result there is increasing interest in alternative therapies and acupuncture is one of those. Eleven studies were included, however acupuncture has not yet been proven to be effective and safe for treating people with epilepsy.
  • Acupuncture for neck pain: We included 10 trails (661 participants) in this review that examined the effects of acupuncture on neck pain for individuals with chronic neck pain (lasting for at least three months). One study also included individuals with neck pain that lasted for at least six weeks, but they considered it to be chronic. Acupuncture was compared to sham acupuncture, waiting list, other sham treatments (sham laser, sham TENS) or other treatments (mobilization, massage, traction). Acupuncture treatments appear to be safe and only minor, transient and benign adverse effects were reported in the trials. The trials were of moderate methodological quality, but the number of participants in each trial was relatively low. There was a range of individuals studied, acupuncture techniques used and outcomes measured, so we could not combine the results of the trials to get an overall picture of the effectiveness of acupuncture. Therefore, we could only draw limited conclusions. Individuals with chronic neck pain who received acupuncture reported, on average, better pain relief immediately after treatment and in the short-term than those who received sham treatments. Individuals with chronic neck pain with symptoms radiating to the arms who received acupuncture reported, on average, better pain relief in the short-term than those who were on a waiting list.

It thus seems that most studies claim the need for more investigations. Also, several methodological shortcomings affect the scientific value of a good portion of the studies. Not too surprising, after all. A few studies do report that acupuncture seems effective in treating selected chronical conditions. Several others seem to prove that the positive effects of acupuncture are of the same magnitude of those of random applications, leading to the conclusion that what works in acupuncture is the placebo effect. However, it seems to me that the last word is not spelt yet.

After reviewing those documents, I remain possibilistic. I am convinced that the placebo effect has a strong influence, possibly explaining all of the alleged beneficial effects of acupuncture. Whether the targeting of nerves does add benefits to the placebo effect is not proven, but might still be true, in specific cases. However, even if such benefits exists, they must be of very small entity, making me doubt that the technique will survive the verdict of a new generation of deeper scientific tests.

To conclude this post, to show that the scientific literature still is undecided on the issue, let me quote a 2005 document, a 300-page review of the treatment of acute pain, Acute Pain Management: Scientific Evidence (Australian and New Zealand College of Anaesthetists and Faculty of Pain Medicine), endorsed by the National Health and Medical Research Council (NHMRC). This exhaustive panoramic only has a single paragraph on acupuncture in Chapter 8:

Reviews of the effectiveness of acupuncture in an acute pain setting suggest that it may be useful for managing pain during childbirth (Smith et al 2003, Level I), idiopathic headache (Melchart et al 2001, Level I) and dental pain (Ernst & Pittler 1998, Level I). It may also be effective in treating postoperative pain. Both preoperative low and high frequency electro-acupuncture reduced postoperative analgesic requirements and the incidence of nausea and dizziness after lower abdominal surgery (Lin et al 2002, Level II). Acupuncture needles inserted preoperatively were also found to reduce postoperative pain, opioid consumption and nausea as well as plasma cortisol and adrenaline (epinephrine) levels (Kotani et al 2001, Level II).
Key message:
Acupuncture may be effective in some acute pain settings (Level I).

Guess the function: results January 21, 2009

Posted by dorigo in physics, science.
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Thanks to the many offers for help received a few days ago, when I asked for hints on possible functional forms to interpolate a histogram I was finding hard to fit, I have successfully solved the problem, and can now release the results of my study.

The issue is the following one: at the LHC, Z bosons are produced by electroweak interactions, through quark-antiquark annihilation. The colliding quarks have a variable energy, determined by probability density functions (PDF) which determine how much of the proton’s energy they carry; and the Z boson has a resonance shape which has a sizable width: 2.5 GeV, for a 91 GeV mass. The varying energy of the center of mass, determined by the random value of quark energies due to the PDF, “samples” the resonance curve, creating a distortion in the mass distribution of the produced Z bosons.

The above is not the end of the story, but just the beginning: in fact, there are electromagnetic corrections (QED) due to the radiation of photons, both “internally” and by the two muons into which the Z decays (I am focusing on that final state of Z production: a pair of high-momentum muons from Z \to \mu^+ \mu^-). Also, electromagnetic interactions cause a interference with Z production, because a virtual photon may produce the same final state (two muons) by means of the so-called “Drell-Yan” process. All these effects can only be accounted for by detailed Monte Carlo simulations.

Now, let us treat all of that as a black box: we only care to describe the mass distribution of muon pairs from Z production at the LHC, and we have a pretty good simulation program, Horace (developed by four physicists in Pavia University: C.M. Carloni Calame, G. Montagna, O. Nicrosini and A. Vicini), which handles the effects discussed above. My problem is to describe with a simple function the produced Z boson lineshape (the mass distribution) in different bins of Z rapidity. Rapidity is a quantity connected to the momentum of the particle along the beam direction: since the colliding quarks have variable energies, the Z may have a high boost along that direction. And crucially, depending on Z rapidity, the lineshape varies.

In the post I published here a few days ago I presented the residual of lineshape fits which used the original resonance form, neglecting all PDF and QED effects. By fitting those residuals with a proper parametrized function, I was trying to arrive at a better parametrization of the full lineshape.

After many attempts, I can now release the results. The template for residuals is shown below, interpolated with the function I obtained from an advice by Lubos Motl:

After multiplying that function by the original Breit-Wigner resonance function, I could fit the 24 lineshapes extracted from a binning in rapidity. This produced additional residuals, which are of course much smaller than the first-order ones above, and have a sort of parabolic shape this time. A couple of them are shown on the right.

I then interpolated those residuals with parabolas, and extracted their fit parameters. Then, I could parametrize the parameters, as the graph below shows: the three degrees of freedom have roughly linear variations with Z rapidity. The graphs show the five parameter dependences on Z rapidity (left column) for lineshapes extracted with the CTEQ set of parton PDF; for MRST set (center column); and the ratio of the two parametrization (right column), which is not too different from 1.0.

Finally, the 24 fits which use the f(m,y) shape, with now all of the rapidity-dependent parameters fixed, are shown below (the graph shows only one fit, click to enlarge and see all of them together).

The function used is detailed in the slide below:

I am rather satisfied by the result, because the residuals of these final fits are really small, as shown on the right: they are certainly smaller than the uncertainties due to PDF and QED effects. The f(m,y) function above will now be used to derive a parametrization of the probability that we observe a dimuon pair with a given mass m at a rapidity y, as a function of the momentum scale in the tracker and the muon momentum resolution.

10,000 comments January 21, 2009

Posted by dorigo in Blogroll, internet, personal.
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Congratulations to Doug, who left comment number 10,000 on this blog yesterday.The number is subtracted of all the spam comments and of the extremely few comments I have felt compelled to censor in the past (mostly for their offensive content).

I unfortunately cannot offer free services to him for the occasion, since this blog is a free service already.

Mate in eight January 19, 2009

Posted by dorigo in chess, games, internet, personal.
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The biggest upsets are really emotionally repaying, in chess as in any other sport. I was down a rook and a piece in a horribly hopeless game played on the internet chess club this evening, when I could exploit to the fullest a silly move by an already relaxed opponent, to give a funny mate-in-eight. Here is the starting position (I am white). White is to move.

Rather than trying to defend from the many threats of black, I throw in one more piece with 1.Bf4! Black answers with the logical 1….Nxf4, but after 2.Qxg7 he needs to choose. A safe 2.Qf8 would see me resign (2….Qe5 3.Ne6 and white does not have any more bullets to fire), but black thinks there must be surely a quick mate: so he plays 2….Nh3+ 3.Kf1.

What to do now ? Black has three minutes to think this over, but he sees no better defence against Qxh8 than 3….Qh6??

I was unable to announce mate in eight -over the internet these luxuries are impossible unless one uses the chat window (considered highly inappropriate during a game), but I did calculate everything to the end in less than half a minute. Here is the sequence, which was played to the bitter end over the board:

4.Re1+ Kd8 5.Qd4+ Kc7 6.Re7+ Kc6

7.Be4+! Kb5 8.Qb4+ Ka6 9.Bd3+ Nc4 10.Bxc4+ b5 11.Qxb5 mate.

A really enjoyable end to a game started with a bad string of blunders on my side!

On the casualty ratio in Gaza January 19, 2009

Posted by dorigo in news, politics.
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In this short post I wish to discuss whether during the 22-day-long war in Gaza the israeli defence force (IDF) has been, as some commenter claimed here, “the most moral army in the world”. It is indeed reported by media that the IDF makes phone calls to civilian houses before those are bombed, that leaflets are spread on areas which will be targeted, etcetera. I think these are commendable actions, but on the other hand the media these days are full of news that report despicable episodes by the israeli army, which tend to demonstrate the opposite. Leaving aside the endless debate that such conflicting evidences would set up, let me stay on the easier ground of mathematics, and aseptically discuss the civilian casualty ratio in Gaza.

First of all, there are a couple of caveats to mention. The ratio is not too easy to ascertain, because -to some extent- many of the Gaza “civilians” might be considered supporters of the Hamas force. So we have to stick to numbers provided by Israel itself, rather than rely on the claims by Hamas that just 48 of its combatants have been killed in the attack. Israel sets that number at “at least 500″, and I will take 500 as a fair estimate, ignoring the Hamas claim and the rather propaganda-sounding “at least” by the IDF.  Let us give the number a 20% uncertainty: 500+-100. As for the total casualties, their number is less uncertain: most sources set it at 1300 or above, if we stick to palestinians who have lost their life until today. More can die of the wounds in the near future, but the ratio we are to compute should not be affected by that.

The other caveat is that one could argue that it is unfair to judge the actions of the IDF on the basis of the casualty ratio, because the action was aimed at eradicating the weapons potential of Hamas rather than Hamas itself, and the weapons had allegedly been concealed in homes, hospitals, schools, places of worship. This objection to me is not too valuable, because it amounts to declaring that the action had been decided in spite of that practice. Or, to put it another way: if Hamas uses the horrible practice of human shields, Israel uses the even more horrible practice of ignoring it!

Now, let us look at the numbers. (1300-500)/500 = 1.6 \pm 0.5, roughly. That means that for each Hamas fighter, more than one civilian has been killed.

Let us now look at some statistics reported one year ago by Haaretz  here, about the civilian casualty ratio of air strikes. It is reported at 1:30.

So I am led to conclude that the IDF considered not enough the air strikes, and needed a different strategy to counter the Kassam missiles; and that they did not really care about the civilian losses they would inflict on palestinians, this time.

And a warning: Of course, I am willing to hear other opinions on the matter; this blog is usually censorship-free. Since, however, I am bored by allegations of being “anti-semitic”, “communist”, of “caring zero for the other wars in the world”, “where were you when Serbia was bombed by your country”, etcetera, I will apply some measure of censorship here. Either leave your name and address, or refrain from posting meaningless, insulting comments, please.

Slow but sure January 19, 2009

Posted by dorigo in Uncategorized.
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Just a quick note – I am getting slow in answering comments these days. That is probably the outcome of the few threads which have developed under my controversial posts on the Gaza war. The comments left there by supporters of the israeli military action on one side, and by supporters of peace on the other side, have been piling up in my “comments managing” page, hiding the good comments on physics posts under them.

I am taking care of answering all comments now, but it takes some time… If you left a comment here a few days ago and checked back later finding it unanswered, check back now.

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