```xml
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<ns4:query_definition xmlns:ns2="http://www.i2b2.org/xsd/cell/crc/psm/1.1/" xmlns:ns4="http://www.i2b2.org/xsd/cell/crc/psm/querydefinition/1.1/" xmlns:ns3="http://www.i2b2.org/xsd/cell/crc/psm/analysisdefinition/1.1/">
    <query_name>Atrial fibrilla@15:37:28</query_name>
    <query_timing>ANY</query_timing>
    <specificity_scale>0</specificity_scale>
    <panel>
        <panel_number>1</panel_number>
        <panel_timing>ANY</panel_timing>
        <panel_accuracy_scale>100</panel_accuracy_scale>
        <invert>0</invert>
        <total_item_occurrences>1</total_item_occurrences>
        <item>
            <hlevel>6</hlevel>
            <item_name>Atrial fibrillation</item_name>
            <item_key>\\i2b2_DIAG\i2b2\Diagnoses\Circulatory system (390-459)\Other forms of heart disease (420-429)\(427) Cardiac dysrhythmias\(427-3) Atrial fibrillation and f~\(427-31) Atrial fibrillation\</item_key>
            <item_icon>FA</item_icon>
            <tooltip>Diagnoses \ Circulatory system \ Other forms of heart disease \ Cardiac dysrhythmias \ Atrial fibrillation and flutter \ Atrial fibrillation</tooltip>
            <class>ENC</class>
            <item_is_synonym>false</item_is_synonym>
        </item>
    </panel>
</ns4:query_definition>

```

I want to find all instances of atrial fibrillation diagnoses within the i2b2 data, with no specific timeframe or accuracy level specified, and with the specificity set to 0 and the invert flag set to 0. The query should be focused on the Circulatory System category, under the Other forms of heart disease subcategory, within the Cardiac dysrhythmias section, specifically looking for Atrial fibrillation and flutter, and more specifically, Atrial fibrillation.