Tag Archives: #pasta

What Is The Impact Of Strong Magnetic Field On the Inner Crust of Neutron Star? (Planetary Science)

Bao and colleagues carried out the study on the influence of strong magnetic fields on the properties of nuclear pasta phases and crust-core transition in the inner crust of neutron star by using the RMF model and the self-consistent TF approximation. They found that as the magnetic field strength “B” is less than 10^17 G, the effects of magnetic field are not evident comparing with the results without magnetic field. But, as magnetic field strength is stronger than 10^18 G, the onset densities of pasta phases and crust-core transition density decrease significantly, and the density distributions of nucleons and electrons are also changed obviously. Their study is published in Physical Review C on Jan, 14, 2021.

Artist impression of Neutron star © Gettyimages

Neutron stars offer special natural laboratories for the study of nuclear physics and astrophysics due to their extreme properties. They consist of extreme neutron-rich matter and their densities can cover more than 10 orders of magnitude from surface to center. It is generally believed that a neutron star mainly consists of four parts, an outer crust of nuclei in a gas of electrons, an inner crust of neutron-rich nuclei with electron and neutron gas, a liquid outer core of homogeneous nuclear matter, and an inner core of exotic matter with non-nucleonic degrees of freedom. From the neutron drip to the crust-core transition, i.e., the density range of inner crust, the stable nuclear shape may change from droplet to rod, slab, tube, or bubble with increasing density. As a result, the so-called nuclear pasta phases are expected to appear in the inner crust of neutron stars, which play a significant role in interpreting a lot of astrophysical observations, such as the giant flares and quasiperiodic oscillations from soft γ-ray repeaters, and glitches in the spin rate of pulsars.

The soft γ-ray repeaters and anomalous x-ray pulsars have already been confirmed as magnetars with very strong surface magnetic fields, which can be as high as 10¹⁴-10^15 G. The magnetic field strength in the core of a neutron star may even reach 10^18 G. So far, the mechanism and origin of strong magnetic fields in magnetars remain unclear, and several hypotheses have been proposed. Duncan and Thompson in their paper suggested that such strong fields could be generated by the dynamo mechanism in a rapidly rotating protoneutron star. It has also been suggested that strong magnetic fields in neutron stars may result from magnetic flux conservation during the collapse of a massive progenitor. It is still under discussion how strong the magnetic fields can be in the crust and interior of neutron stars.

Now, Bao and colleagues in their work, employed the Wigner-Seitz (WS) approximation to describe the inner crust and use the self-consistent Thomas-Fermi (TF) approximation to calculate the nonuniform matter with considering various pasta configurations. In the TF approximation, they treated the surface energy and the distributions of nucleons and electrons self-consistently. While, they adopted the RMF model to describe nucleon-nucleon interaction. In the RMF model, nucleons interact with each other via the exchange of scalar and vector mesons.

FIG. 1: (Color online) Binding energy per nucleon E/N of pasta phases as a function of baryon density nb for TM1 (upper panel) and IUFSU (lower panel) models with different magnetic field strength, B = 0 (dashed line), B = 10^17 G (dotted line), and B = 10^18 G (solid line). The results with B = 10^18 G ignoring the anomalous magnetic moments of nucleons for IUFSU model are also plotted by dash-dotted line for comparison. The onset densities of various non-spherical pasta phases are indicated by the circle dots. © Boa et al.

They found that the pasta phase structures and the crust-core transition density were changed obviously when, the magnetic field strength is as large as B = 10^18 G, where the binding energy per nucleon E/N is lower than the results with B = 0, and the onset densities of various pasta phases and crust-core transition density become smaller. However, the proton fraction Yp with binding energy, B = 10^18 G is larger than that with B = 0, since the protons occupy the lowest Landau level. The impacts of anomalous magnetic moments of nucleons are almost invisible in the case of B = 10^17 G, but they have to be taken into account for a stronger magnetic field as B = 10^18 G.

FIG. 2: (Color online) Proton fractions of pasta phases Yp as a function of baryon density nb for TM1 (upper panel) and IUFSU (lower panel) models with magnetic fields B = 10^18 G (solid line) and B = 0 (dashed line). The results with B = 10^18 G ignoring the anomalous magnetic moments of nucleons are also plotted by dash-dotted line for comparison. Different colors correspond to various pasta structures. © Boa et al.

In general, the radius of WS cell decreases with increasing B, while the size of nucleus increases with B, which results in the charge number and nucleon number of the nucleus varying with B. The density distributions of nucleons and electrons with B = 10^18 G are clearly different from the results with B = 0.

FIG. 3: (Color online) Radius of WS cell rws (thick line) and nucleus rin (thin line) as a function of baryon density nb for TM1 (upper panel) and IUFSU (lower panel) models with magnetic fields B = 10^18 G (solid line) and B = 0 (dashed line). The jumps in rws and rin correspond to shape transitions in pasta phases. © Boa et al.

In order to check the model dependence of the results obtained, they adopted two successful RMF parametrizations, TM1 and IUFSU, with different symmetry energies and their slopes, which play an important role in determining the properties of inner crust of neutron star with strong magnetic fields. The TM1 model has been successfully used to construct the equation of state for neutrons stars and supernova simulations. Compared with TM1 model, an additional ω-ρ coupling term is added in IUFSU model, which plays an important role in modifying the density dependence of symmetry energy and affects the neutron star properties. The symmetry energy slope L in TM1 model is as large as 110.8 MeV, while L in IUFSU model is 40.7 MeV.

“By comparing the results from these two models, we found that the features with strong magnetic fields due to the symmetry energy and its density slope are similar to the results with B = 0, which are consistent with our earlier study.”, said Bao. “A smaller slope L leads to more complex pasta structures. For the TM1 model with a larger slope L, only droplet appears in the inner crust of neutron star for B = 0. However, some non-spherical pasta phases arise before crust-core transition for B = 10^18 G, even though the crust-core transition density becomes smaller.”

FIG. 4: (Color online) Density distributions of protons, ρp (a), neutrons, ρn (b), and baryons, ρb (c), in the WS cell at nb = 0.01, 0.02, 0.03 fm-³ (top to bottom) obtained in the TF approximation for TM1 model with magnetic fields B = 0 (dashed line) and B = 10^18 G (solid line). The cell boundary is indicated by the hatching © Boa et al.
FIG. 5: (Color online) Same as Fig. 4, but for IUFSU model © Boa et al.

“It would be interesting to further study the nuclear pasta phase with strong magnetic fields and their impacts on the observations of neutron star.”, concluded of the study.

Reference: S. S. Bao, J. N. Hu, H. Shen, “Impact of strong magnetic fields on the inner crust of neutron stars”, Phys. Rev. C 103, 015804 – Published 11 January 2021. https://doi.org/10.1103/PhysRevC.103.015804 https://journals.aps.org/prc/abstract/10.1103/PhysRevC.103.015804

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An Easy Trick to Eat Slower and More Mindfully (Psychology / Food)

Do you eat pizza for breakfast?

Do you begin the day with a bowl of pasta?

If you answered yes to either of these questions, you might already be trying an easy trick to help you to eat more mindfully. A recent study published in the journal, Appetite, found that mixing up your typical eating habits can help you to eat slower, eat less while also feeling more satisfied.

©gettyimages

The Study

Seventy-eight participants were served either a typical lunch of cheese and tomato pasta or breakfast food of porridge with milk and honey. When they served lunch for breakfast, the results showed that participants ate slower, less food, and reported feeling more satisfied.

In part, people tend to naturally slow down and pause when things are unusual or out of the ordinary. Breaking out of your typical automatic ruts and routines is important in starting to eat more mindfully.

What Is Mindful Eating?

Mindful eating is not a diet. There are no menus or recipes. It’s learning more about how you eat than what you eat. Let’s face it. We have a lot of mindless eating habits that keep us stuck. Such as sitting on the couch watching TV absent-mindlessly munching on chips. Or, wandering into the kitchen to find a snack when you are bored or stressed out. The good news is that there are some easy ways to get started amping up your awareness. Conscious awareness helps to shift you out of old habits.

Benefits:

Research on mindful eating has shown mindful eating to help reduce emotional eating, stop mindless munching, lose weight, stop binge eating, and best of all enjoy a positive relationship with food (such as enjoying it more and stressing less about it!).*

Mindful Eating Challenge:

It’s easy to eat on autopilot. Today, I challenge you to try something new and shake up your typical routine.

• Sit in a different seat at the kitchen table.
• Eat your lunch for breakfast—a peanut butter sandwich, a salad, leftover meatloaf.
• Use a special bowl you rarely use.
• Eat something new and different.
• Notice how it feels to break out of routine eating habits. Do you eat slower? Enjoy it more? Notice how satisfied you feel? These are all aspects of mindful eating.

References: C.J.McLeod, L.J.James, G.L.Witcomb, Appetite, Volume 154, 1 November 2020, 104799. Eating rate and food intake are reduced when a food is presented in an ‘unusual’ meal context. *https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4046117/ doi: https://doi.org/10.1016/j.appet.2020.104799

This article is republished here from psychology today under common creative licenses

Why You Always Have Room For Dessert? (Food / Science)

You’ve just finished an amazing meal, and you could not eat another bite. Until the pie arrives, and you suddenly have room for one — make that two pieces. Why does that happen? According to one school of thought, it all comes down to something called sensory-specific satiety. That is, you weren’t actually full; your senses were just bored.

Sensory-specific satiety (SSS) refers to the idea that the more you eat one kind of food in a single sitting, the less appealing that food becomes. It feels like you’re full, but often it’s just that your brain has stopped being excited by the flavors of your meal. When the pie arrives, suddenly you’re faced with something new and different, and you’re ready to eat again.

A review published in the International Journal of Obesity back in 2003 found that SSS doesn’t just apply to dessert. You can get bored of any flavor, texture, or color of food. The most familiar example of SSS for most of us is in savory food: You eat a savory meal until you feel satisfied, then sweet food looks appealing. But the opposite has also been shown to be true (“I’m stuffed after my ice cream, but I could sure go for a steak!”). You can get tired of a food even if there’s no difference in flavor; candy of one color stops tasting as good than identical candies of another color, and the same goes for shapes of pasta.

What does this mean for those of us watching our waistlines? Well, it turns out that there may be a way to game the system. A 2009 study published in the British Journal of Nutrition found that you can make SSS happen faster — that is, make yourself feel full before you’ve overeaten — if you eat in smaller doses.

Subjects who were asked to drink as much orange soda as they wanted consumed less if they drank in smaller sips. The researchers concluded that the smaller sips led to more sensory exposure per ounce, so the participants reached sensory-specific satiety faster. So the next time dinner comes with the promise of pie, don’t skip dessert. Just eat in smaller bites.

Only 3 People Know How To Make Rarest Pasta On The Earth (Food)

Imagine yourself on a pilgrimage. Traveling by foot, you and hundreds more make a rugged journey uphill in search of a singular experience. You’re not having a religious awakening. You’re just trying to get some pasta. But not just any pasta: it’s the rarest pasta on Earth.

Sufilindeu goes back at least 200 years — possibly as far back as 300. However old the recipe is, it’s a family affair. For centuries, the secret has been passed down from mother to daughter in the remote mountain village of Lula. Today, the recipe is kept by three women: Paola Abraini, her niece, and her sister-in-law. These are the only people on the planet capable of creating the dish, which consists of impossibly thin strands arranged in an intricate, gauzy lattice. It’s that incredibly skinny, fine structure that gives the pasta its name, which translates as “threads of God.” Angel hair, eat your heart out.

To try su filindeu, you’ll have to do a couple of things. First, you’ll have to wait until one of the biannual Feasts of San Francesco, in May and October. Those are the only times that the women make their pasta available to the public. Next, you’ll have to travel to the island of Sardinia, and then head towards the mountainous inland. The final part of your journey you need to complete on foot. It’s a 20-mile (32-kilometer) trek uphill with a couple hundred fellow travelers. At the end of it, you’ll be rewarded with a footbath and a bowl of rich but delicate su filindeu.

Actually, we might be exaggerating the secrecy of the secret. It’s not necessarily that the masters of su filindeu refuse to share the recipe. It’s probably more accurate to say that other would-be pasta-makers just can’t master it. In 2016, celebrity chef Jamie Oliver attempted to learn the technique but gave up after two hours. Abraini was willing to try to teach him, but he was in for an uphill battle because he didn’t grow up learning how to make the pasta. As Abraini told the BBC, “Many people say that I have a secret I don’t want to reveal. But the secret is right in front of you. It’s in my hands.”

The World’s Rarest Pasta Is Made Entirely by Hand