What is real scientific integrity?

According to the Oxford English Dictionary Integrity = "The quality of being honest and having strong moral principles".

When people talk about scientific integrity and misconduct they mostly have a narrow definition which means "don't make up data."

However, I think we need to consider a broader definition of integrity that relates to all communications and messages.

Scientists talk about their research in a wide range of forums:

• private discussions
• articles in luxury journals
• articles in professional society journals (PRA, JCP etc)
• grant applications and job applications
• seminars at universities and conference presentations
• press releases and interviews
• public lectures and popular books

Yet it seems it has now become quite acceptable to have different messages (claims and conclusions) in different forums. This post was stimulated by a perceptive comment by Steve W on a previous post.

My finding is if you talk to the authors of luxury papers with controversial or sexy explanations, that they will be the first to admit their own skepticism regarding their explanations of the data. But somehow this skepticism is not conferred to the text, because the luxury journals like clear, concise, authoritative explanations. Most of the details get hashed out later in less prominent, but longer form journals, and these are only followed closely by those within the specific community. 

For a concrete example see a recent post by Peter Woit about the basic question, "Is string theory experimentally testable?" He highlights a significant inconsistency between the answers in a preprint, the published version in PRL, a press release, and a public talk by Amanda Peet.

From a spin liquid to a correlated Dirac metal

There is an interesting paper
Theoretical prediction of a strongly correlated Dirac metal 
 I. I. Mazin, Harald O. Jeschke, Frank Lechermann, Hunpyo Lee, Mario Fink, Ronny Thomale, Roser Valentí

The compound Herbertsmithite ZnCu3(OH)6Cl2 has attracted a lot of interest because it is a Mott insulator with a layered crystal structure where the Cu2+ ions (spin 1/2) are arranged in a kagome lattice.
There is some evidence both experimentally and theoretically that the ground state is a spin liquid.
[However, inevitably there are complications such as the role of impurities and the Dzyaloshinskii-Moriya interaction].

In this paper the authors replace the Zn2+ ions with (isoelectronic) Ga3+ ions. This means that in non-interacting electron picture the bands go from half filling (n=1) to two-third filling (n=4/3). This is of particular interest because for a tight-binding model on the kagome lattice there are symmetry protected Dirac points, just like in graphene, at this band filling.

There are subtle interlayer effects because the kagome layers order ABCABC....

This changes the three-dimensional Bravais lattice from hexagonal to rhombohedral and a doped system will have a Fermi surface like that below.

However, one needs to take into account the strong interactions associated with the localised Cu orbitals that lead to a Mott insulator at half filling. The authors use a range of theoretical techniques (rotationally invariant slave bosons, functional RG, Dynamical Cluster Approximation (DMFT)), to investigate instabilities in the associated Hubbard model.
They find a subtle competition between metallicity, charge ordering, ferromagnetism, and f-wave superconductivity.

Hopefully, someone will make this compound soon!

I thank Ben Powell for bringing the paper to my attention. He and Anthony Jacko recently considered an organometallic material with a rich band structure that interpolates between honeycomb and kagome.

The challenging interface of science, policy, and politics

Last week I went to an interesting talk What are the effects of dredging on the Great Barrier Reef?

by Laurence McCook, at the Global Change Institute at UQ.

I went because I knew Laurence in my undergraduate days at ANU. In first year we had all the same lectures, tutorials, and labs. (I guess groups were assigned based on the alphabet.) We became friends and he introduced me to many beautiful places for bushwalking [backpacking] and cross country skiing near Canberra.

There is a piece on the Conversation that gives a brief summary of the issues associated with the report from the expert panel that Laurence and  Britta Schaffelke co-chaired. Basically, it involved a "cat herding" exercise with 17 experts from industry, government, and universities. I am always impressed by people who manage such enterprises and can produce concrete useful outcomes. I think it requires considerable patience, political skills, and leadership. 

A helpful figure is below.

Aside: it would be interesting to try and do an exercise like this for topics such as cuprate superconductors, topological quantum computing, water, glasses, quantum molecular biophysics......

So what effect does dredging have?

Specifically, which of the effects is most likely to do the greatest environmental damage?

It seems that the ongoing turbidity [cloudy water] and sedimentation associated with sediment dynamics could be the biggest problem. But, this is also one of the most poorly understood processes. 

The figure below summarises some of the complex processes involved. Modelling this presents a major challenge (and some interesting science).

A problem with these exercises where science meets policy meets politics, particularly on controversial issues, is that they can highlight uncertainty and the general public does not like that. Science is meant to be certain. People want black and white answers. "Dredging is harmless and we should not worry about it vs. Dredging is an environmental disaster and should be banned".

It is interesting that of "10 scientific ideas that scientists wish you would stop mis-using" the first is Proof.

Holon-doublon binding as the mechanism for the Mott transition

What is the mechanism of the Mott metal-insulator transition?
After 50 years this remains a debated issue.

A number of distinct mechanisms for the transition have been proposed. These include those due to Brinkman and Rice (where the quasi-particle weight in the metallic phase approaches zero as the transition is approached), Hubbard (where vanishing of the charge gap occurs when the upper and lower Hubbard bands overlap), or Dynamical Mean-Field Theory (DMFT) which combines both these features.

My collaborators and I discuss an alternative mechanism in a paper that we just finished.

Holon-Doublon Binding as the Mechanism for the Mott transition
Peter Prelovsek, Jure Kokalj, Zala Lenarcic, and Ross H. McKenzie

 We study the binding of a holon to a doublon in a half-filled Hubbard model as the mechanism of the zero-temperature metal-insulator transition. In a spin polarized system and a non-bipartite lattice a single holon-doublon (HD) pair exhibits a binding transition (e.g., on a face-centred cubic lattice), or a sharp crossover (e.g., on a triangular lattice) corresponding well to the standard Mott transition in unpolarized systems. We extend the HD-pair study towards non-polarized systems by considering more general spin background and by treating the finite HD density within a BCS-type approximation. Both approaches lead to a discontinuous transition away from the fully polarized system and give density correlations consistent with numerical results on a triangular lattice.

Two things I found (pleasantly) surprising in this study were:

-two "simple" analytical approaches (retraceable path approximation and a BCS-type variational wave function) seem to capture much of the essential physics.

-one can learn quite a lot by approaching the problem from the highly (spin) polarised limit.

We welcome comments and suggestions.

Battling High Impact Factor Syndrome II

Last friday we had a great colloquium at UQ from Carl Caves on High-impact-factor syndrome: What, why, and what to do.

Much of the talk followed Carl's article The High-impact-factor syndrome on The Back Page of the American Physical Society News. I posted about it before.

Here are a few new things that emerged.

Reinhardt Werner had a nice piece in Nature, The focus on bibliometrics makes papers less useful. The comments and his responses are worth reading.

Last week Nature published The Leiden Manifesto for Research Metrics.

Nature Publishing Group has launched the Nature Index to rate individuals, departments, institutions, and countries. They claim it is a "global indicator of high quality research". It is based on only 68 journals, including many NPG journals! For example, the only APS journals included are PRL and the Rapid Communications parts of PRA, PRB, and PRD. Journal of Chemical Physics is not included. There are no mathematics journals.
I find this enterprise rather disturbing.

One needs to consider not just the Impact Factor which is a mean (average) but rather the width and the shape of the distribution.
For example, for Nature Physics, the bottom 50 per cent have 7 citations/paper/year. This is the same as the impact factor for PRL. Hence, even if you believe in such citation measures, half of the Nature Physics papers are really just like a PRL!

What are some of the problems with HIF syndrome?

Campbell's law will come into play.

"The more any quantitative social indicator (or even some qualitative indicator) is used for social decision-making, the more subject it will be to corruption pressures and the more apt it will be to distort and corrupt the social processes it is intended to monitor."

Gaming the system is inevitable.

Scientists surrender their research agenda to the Editors of Nature.

There is a tendency toward short, punchy, "hit and run" papers.

There is a trend towards hype and salemanship and fluff. This means a reduction in the commitment to the search for truth and scientific integrity, two things that set science apart as a social enterprise.

Not seeing the pseudogap in ultra cold 2D atoms

Two weeks ago it was nice to have Meera Parish visit UQ and give a colloquium Fermions in Flatland. She recently moved to Monash University from University College London.

One important point she made was the comparison of the two figures below, showing a colour intensity plot of the one fermion spectral function A(E,k) for a two-dimensional Fermi gas near the unitary limit (BCS-BEC crossover).

The bottom figure is experimental data from a Nature paper, 

Observation of a pairing pseudogap in a two-dimensional Fermi gas.

It makes much of the possible connection to the pseudogap seen in cuprate superconductors.

The top figure is from a theory paper

Pair Correlations in the Two-Dimensional Fermi Gas 

Vudtiwat Ngampruetikorn, Jesper Levinsen, and Meera M. Parish

Therefore, our results suggest that the observed pairing gap [Nature paper] effectively arises from two-body physics and does not correspond to a pseudogap regime. This view is further supported by the fact that the pairing gap in the spectrum persists to very high temperatures well above Tc, as shown in Fig. [above]. Moreover, we see that the “closure” of the gap with increasing temperature appears to be due to the thermal broadening of the two branches.

An earlier post discussed more recent measurements of the spectral function in three-dimensional ultra cold fermionic atoms near the unitary limit.

The challenge of setting priorities

We all have limited time, energy, and money.
We all have priorities even if we can't clearly state them or don't publicly state them.
Setting priorities is a challenge not just for individuals but also for departments, institutions, and research fields.
I think rarely does this happen well.

When priorities are not clearly stated, whether from individuals to institutions, "stake holders" are left trying to guess and speculate what the priorities really are.

Publicly stated priorities too often look like a "dog's breakfast": a mishmash of wish lists from competing interests, or a laundry list...

I feel this sometimes applies to lists of "research strengths" or "research priorities" that  Australian universities come up with every few years.

Every few years departments in Australian universities are extensively reviewed, leading to a list of 20-30 specific recommendations, that the department chair is then held accountable to implement before the next review. However, these recommendations seem to be given equal weight whereas they really may vary significantly in their importance and value.

Another example are the Sustainable Development Goals from the United Nations, which are the successor to the eight Millennium Development Goals. In spite of their many faults I think the MDGs had merits and did lead to some significant outcomes. But, the SDGs (17 goals with 169 targets) may lead to no significant outcomes due to their breadth, as critiqued by The Economist.

Because condensed matter physics and chemistry are diverse and diffuse fields I think they can suffer in the funding game, particularly in some countries, when you have competing interests that will publicly (or privately when reviewing grant proposals) put each other down. In contrast, some fields such as high energy physics and astrophysics are sometimes very good at bringing their community together to privately agree on priorities and then publicly lobby for support, particularly for large projects.
I think a recent exception for condensed matter is that finally the community has agreed that growth of high quality single crystals of quantum materials is a long-neglected priority, something that the Moore Foundation has picked up on.

Do why don't we set priorities?

It is hard work.

It involves incomplete information where the future is uncertain.
We don't know what projects or people are going to be fruitful in the long term.

It may involve the painful process of saying no.
We have to say no to many good things in order to realistically pursue a couple of excellent goals.
Sometimes it is time to quit and cut our losses.

Some people will be disappointed and/or get offended.
They and/or their pet projects may not be a priority.
This is particularly why often real priorities are not clearly stated or when they are they are a "dogs breakfast".

We are waiting for a miracle to happen.
If all of the sudden we got a big breakthrough on the project, or a new big grant or a brilliant student or something else things would become easier and simpler.

Having said all this, I think having set the priorities is just the first challenge. Sticking to them in the face of setbacks, changing circumstances, criticism, and discouragements can be an even greater challenge.

So, how do you set priorities? If not, why not?
Should chemistry and condensed matter be more clearly setting priorities? Is that politically realistic?