Weakly Electric Fish Dominance

Submitted by semans on Tue, 12/10/2019 - 17:15

The use of electrocommunication to mediate dominance hierarchies and aggressive encounters has been shown in both pulse-type and wave-type fish. Electrocommunication in these contexts has been  related to hormones and even to social history in at least one species, Brachyhypopomus gauderio (Gebhardt et al. 2012, 623; Fugère et al. 2011, 197; Salazar & Stoddard 2009, 399; Cuddy et al. 2012, 4; Raab et al. 2019, 1). Weakly electric fish seem to use different EOD frequencies, EOD lengths, and IDI patterns as competitive indicators for establishing dominance hierarchies and in bouts of ritualised aggression (Gebhardt et al. 2012, 623; Fugère et al. 2011, 197; Salazar & Stoddard 2009, 399; Cuddy et al. 2012, 4; Raab et al. 2019, 1). Research into dominance and aggression has focused largely on wave-type fish (Fugère et al. 2011, 197; Salazar & Stoddard 2009, 399; Cuddy et al. 2012, 4; Raab et al. 2019, 1). In the Sternarchrohynchus genus, EOD frequency has been correlated with body size, and it seems that fish with higher EOD frequencies are dominant over fish with lower EOD frequencies regardless of sex (Fugère et al. 2011, 198). In contrast, the role of EOD frequency in establishing dominance has only been shown in male A. leptorhynchus (Cuddy et al. 2012, 4). Males with higher EOD frequency are dominant and show increased 11-ketotestosterone levels, an important hormone in male electrocommunicative aggression and courtship (Cuddy et al. 2012, 10). However, this study also found that type 2 chirps previously characterised as purely aggressive signals, in fact, do not serve a threatening purpose but may instead signal submission in A. leptorhynchus (Cuddy et al. 2012, 10). It also revealed that type 1 chirps, delineated prior as courtship signals, do not serve this purpose (Cuddy et al. 2012, 10). In holding with this pattern, A. leptorhynchus males with higher EOD frequencies spend more time in habitats that provide good shelter, and are more explorative than males with lower EOD frequencies (Raab et al. 2019, 7). This is likely due to territoriality. Lower EOD males often have to look for new shelter when they lose dominance bouts against higher EOD males which have secured a higher quality territory (Raab et al. 2019, 8).

AnComm Final 1 PP

Submitted by semans on Tue, 12/10/2019 - 17:13

The paper on song sparrows studies the effects of the transfer function, reverberation, and noise masking of the environment on the trill song of chipping sparrows, with a focus on divergent solutions as a result of intraspecific song variation. A transfer function is a way of describing how the environment filters sound and causes frequency pattern degradation. Urban environments often have transfer functions which favour an intermediate frequency range above low frequency background noise but below frequencies that easily reverberate. Reverberation is a temporal pattern distortion that contributes strongly to impeding signal transmission by adding a tail to notes. As sound waves impact objects they are reflected, which can lead to slurring of both syllable form and pattern. Additionally, due to reverberation, sounds take different paths that can cause both amplitude and frequency interference. The effects of reverb are most pronounced in signals of high frequency, high bandwidth, high duration, and low internote time. In order to compensate for reverberation high obstruction environments such as cities, birds often change their signals by: decreasing minimum frequency, decreasing the number of amplitude and frequency modulations, and increasing internote time. However, in order to transmit their signals above background noise, birds tend to increase the frequency and amplitude of their vocalisations. Although, these modulations can often be hard to separate due to the Lombard effect. Lastly, amplitude and frequency modulated trills are often used by female songbirds as measures of vocal performance, based on how close the male sings to the biophysical limit of the bandwidth to rate ratio. Males which sing closer to this limit are preferred by females and can better defend their territories. In urban environments with highly reflective structures and high background noise, trills suffer heavily from the effects of reverberation and therefore vocal performance is perceived as being poorer. In turn, this has an effect on how well males can both attract females and defend their territories, which means that urban environments could generate unique intra- and intersexual selection pressures.

tuesday draft

Submitted by mlabib on Tue, 12/10/2019 - 12:29

After watching the short film “In Sickness and in Wealth”, I have learned many statistics which saddens me, especially given such poor statistics for a country who spends 2 trillion dollars spent on medical care. Most of my family lives in the United States, so to learn that we have very poor health rates and disease rates scare me and my families future.In this paper, I will be exploring three major concepts, the sadness’ going on in Louisville, excess death (low employment grade deaths), racism and health and lastly solutions to U.S health inequalities. . These three concepts connect as they are all correlated in one way. In America We live shorter and sicker lives. 30th in life expectancy. We are at the bottom of the list, and babies die earlier in America than Malta, Slovenia. This is sad considering we are much more advanced than them. Lastly, 47 million of us do not have health care coverage. Unfortunate reality. 


Methods cont.

Submitted by zalam on Tue, 12/10/2019 - 11:01

Nevertheless, there is a growing body of research surfacing every now and then about potential biomarkers for diagnosing AD early and potential therapies. A study done in Umea University Hospital in Sweden looks at how hormones released by our adrenal glands (adrenocortical) and our reproductive organs (gonadal) can essentially help to detect AD in its early stages. Majority of the people diagnosed with this disease fall in the category of mid 60s and older. As our body ages, it is normal for our hormones to start depleting, especially reproductive ones (estrogen and testosterone). However, in this study, the findings were quite different. They were able to obtain 33 patients with mild to moderate AD (12 men and 21 women, aged approximately 76 years old). They were compared to 22 healthy patients who were already part of a Longitudinal study at the Umea Hospital. They were part of the control group that is usually present for comparison. They had exclusion factors that included medication use, acute medical illness, endocrine disorders, depression, infectious diseases, prostatic hyperplasia, smoking and excessive alcohol intake. 

Abstract Redo

Submitted by nskinner on Mon, 12/09/2019 - 21:46

Abstract. The stability of slopes is correlated with the vegetation on that slope regarding stability (Fan, Lai 2104). The root system of plants plays a pivotal role in the stability of a slope, and it is questionable if the slope itself also determines what vegetation is present and at what age that vegetation will reach; given that it is living on a slope. If significant differences between individual sizes of vegetation can be found on different slopes, than this could be due to differences in habitat. It was predicted that there would be smaller trees on steeper slopes and larger trees on the flat site. To determine if there are different sized trees in different habitats, measurements of the diameter at breast height (dbh) of trees on a north facing slope, south facing slope and a flat site were takenWhen looking at all species in each replicate, the north and south slopes did not differ from the flat as much as what was predicted. There was no statistical difference in the size of trees on the north and south slopes as compared to the flat site. 


Submitted by damianszyk on Mon, 12/09/2019 - 21:10

New research has been done to show that killer whale grandmothers who no longer can reproduce increased the survival rate of their grand-offspring. This may be due to the fact that these killer whale grandmothers have more time to focus on their grand-offspring if they do not have offspring themselves to take care for. Research shows that female killer whales that are no longer reproducing provide an important leadership role. Male killer whales often have a shorter life expectancy, with many not living beyond 30 years. On the other hand, female killer whales don't stop reproducing until they're in their 30s-40s and can live decades after that as well. The findings from this research helps us better understand the factors that are driving the reproductive success of the whales. 



Alzheimer's methods

Submitted by zalam on Mon, 12/09/2019 - 13:37

The high androgen levels in women (mild to moderate AD) in low stress environments shows the altered metabolism of the androgens. The significant correlations between DHEA and cortisol, androstenedione and cortisol indicated that hormone production in the adrenal cortex of the kidneys were like that of younger people. In another study mentioned in this paper, associated high levels of cortisol and DHEA with cognitive dysfunction. There were higher chances of performing better with lower levels of DHEA. Later in the study, they had said that further investigation was required to assess the androgen and gonadal hormone metabolism as they had only reported increased basal androgen levels. In another study, they investigated the thyroid hormone levels in the cerebrospinal fluid (CSF – present to keep the brain afloat and washout any toxins) and find a correlation to the AD severity in patients with normally functioning thyroids. Thyroid hormone (TH) helps in metabolism in the brain and hence can be found in the CSF. There are several forms of TH – they are usually numbered as T2, T3, T4etc. They used something called lumbar puncture to extract spinal fluid from people (sounds pretty painful!). They used highly specific techniques called mass spectrometry and high performance liquid chromatography to assess the CSF containing thyroid hormones. They had about 35 patients (9 males and 26 females, approximately 66 years). The CSF TH concentrations were representative of the blood TH concentration. The AD patients were diagnosed through CT scans, neuropsychological tests, MRI and Mini-Mental State Examination (MMSE). The control group had 10 subjects with normal cognitive abilities and normal MMSE. They had undergone lumbar puncture due complains of severe headaches. Exclusion criteria included thyroid problems, abnormalities of CSF routine analysis or any proof that the barrier between their blood vessels and brain was damaged by in depth analysis of the CSF. 

Reflection 1

Submitted by semans on Mon, 12/09/2019 - 11:15


    At the start, the drafts seemed tedious to me, an exercise in producing quantity rather than quality. This feeling persisted throughout the semester and for most of the class I failed to see the point of writing such an abundance of paragraphs. It occurred to me a few times that there was some purpose to the task that yet escaped me. Nevertheless, throughout writing the drafts I never felt that they had any point. Both the act of writing and the product had no meaning to me as the drafts were just reworded fragments of my notes. However, in hindsight it occurs to me that the function of the drafts was just that, to produce quantity and not quality. In having to write so much, I eventually achieved a point where these rough paragraphs simply flowed onto the page and, very unusually, I wasn’t editing my sentences as I was writing them. I now realise that it wasn’t about the content but about the process. Thus, although the act of writing the drafts never seemed to have a point to me, they have fundamentally changed how I write and how I approached this course’s projects. 

Perfect Paragraphs

    At the beginning of the semester, much like the drafts, the perfect paragraphs seemed an exercise in tediousness. Having to edit one of my drafts every week seemed pointless to me, and this feeling remained throughout most of the semester. While I was writing the perfect paragraphs I didn’t feel like I was improving my writing in any way, and the products of my efforts meant nothing to me. I never spent time thinking about the purpose of the perfect paragraphs, they were just another task I had to complete every week. However, upon reflection, I realise that in making the perfect paragraphs I edited my drafts a lot more than I usually edit my writing. Before this class, I used to edit my writing immediately after having finished an assignment. In doing the perfect paragraphs I was often forced to edit my drafts several days later. As such, I was editing my drafts with a fresh perspective that wasn’t as affected by what I was trying to say in my draft but rather by how the message of the draft actually came across to the reader. In sum, even though the purpose of the perfect paragraphs was not immediately obvious to me, they have changed how I edit my writing.


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